科学家发现一种稳定聚变等离子体的过程（附原文） 诸平 Physicists Allan Reiman, left, and Nat Fisch. Credit: Elle Starkman/PPPLOffice of Communications 据物理学家组织网（ phy.org ）2019年1月9日报道,来自 美国能源部(DOE)普林斯顿等离子体物理实验室( Princeton Plasma Physics Laboratory， PPPL) 的消息，该实验室的科研人员已经发现了一种稳定聚变等离子体的过程。 科学家正在寻找能够引起聚变反应的外力,就像太阳和星星为地球提供的能量，必须保持超高温等离子体不受破坏。现在,美国能源部(DOE)普林斯顿等离子体物理实验室(Princeton Plasma Physics Laboratory,PPPL)研究人员发现了一种能够有助于控制中断被认为是最危险的聚变等离子体的方法。 复制融合（Replicating fusion）可以为城市和工业提供实际上是无限的清洁能源，但是，复制融合释放出的能量就是等离子体物质态的原子核聚合过程中释放出的能量，这种能量几乎是无限的。然而，捕捉和控制聚变能是全球科学与工程研究人员面临的一个关键性的挑战。 PPPL的发现已经在《物理评论快报》（Physical Review Letters）于2018年11月30日发表——A. H. Reiman, N. J. Fisch.Suppression of Tearing Modes by Radio Frequency Current Condensation.Physical Review Letters,2018, 121: 225001.DOI: 10.1103/PhysRevLett.121.225001. 2018 Suppression of Tearing Modes by Radio Frequency Current Condensation.pdf 更多信息请注意浏览原文或者相关报道 Scientists discover a process that stabilizes fusion plasmas January 9, 2019 by John Greenwald, Princeton Plasma Physics Laboratory Scientists seeking to bring the fusion reaction that powers the sun and stars to Earth must keep the superhot plasma free from disruptions. Now researchers at the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL) have discovered a process that can help to control the disruptions thought to be most dangerous. Replicating fusion, which releases boundless energy by fusing atomic nuclei in the state of matter known as plasma, could produce clean and virtually limitless power for generating electricity for cities and industries everywhere. Capturing and controlling fusion energy is therefore a key scientific and engineering challenge for researchers across the globe. Creating magnetic islands The PPPL finding, reported in Physical Review Letters, focuses on so-called tearing modes—instabilities in the plasma that create magnetic islands, a key source of plasma disruptions. These islands, bubble-like structures that form in the plasma, can grow and trigger disruptive events that halt fusion reactions and damage doughnut-shaped facilities called tokamaks that house the reactions. Researchers found in the 1980s that using radio-frequency (RF) waves to drive current in the plasma could stabilize tearing modes and reduce the risk of disruptions. However, the researchers failed to notice that small changes—or perturbations—in the temperature of the plasma could improve the stabilization process, once a key threshold in power is exceeded. The physical mechanism that PPPL has identified works like this: •The temperature perturbations affect the strength of the current drive and the amount of RF power deposited in the islands. •The perturbations and their impact on the deposition of power feedback against each other in a complex—or nonlinear—manner. •When the feedback combines with the sensitivity of the current drive to temperature perturbations, the efficiency of the stabilization process increases. •Furthermore, the improved stabilization is less to likely to be affected by misaligned current drives that fail to hit the center of the island. The overall impact of this process creates what is technically called RF current condensation, or concentration of RF power inside the island that keeps it from growing. The power deposition is greatly increased, said Allan Reiman, a theoretical physicist at PPPL and lead author of the paper. When the power deposition in the island exceeds a threshold level, there is a jump in the temperature that greatly strengthens the stabilizing effect. This allows the stabilization of larger islands than previously thought possible. Beneficial to ITER This process can be particularly beneficial to ITER, the international tokamak under construction in France to demonstrate the feasibility of fusion power. There is worry about islands getting large and causing disruptions in ITER, Reiman said. Taken together, these new effects should make it easier to stabilize ITER plasmas. Reiman worked with Professor Nat Fisch, associate director for academic affairs at PPPL and coauthor of the report. Fisch had demonstrated in a landmark 1970s paper that RF waves could be used to drive currents to confine tokamak plasmas through a process now called RF current drive. Fisch points out how it was Reiman's groundbreaking paper in 1983 that predicted that these RF currents could also stabilize tearing modes. The use of RF current drive for stabilization of tearing modes was perhaps even more crucial to the tokamak program than using these currents to confine the plasma, Fisch said. Hence, he said, Reiman's 1983 paper essentially launched experimental campaigns on tokamaks worldwide to stabilize tearing modes. Moreover, he added, Significantly, in addition to predicting the stabilization of tearing modes by RF, the 1983 paper also pointed out the importance of the temperature perturbation in magnetic islands. Underappreciated feature The new paper takes a fresh look at the impact of these temperature perturbations on the islands, a feature which has been underappreciated since the 1983 paper pointed to it. We basically went back 35 years to carry that thought just a bit further by exploring the fascinating physics and larger implications of positive feedback, Fisch said. It turned out that these implications might now be very important to the tokamak program today. The theoreticians began their recent work with a simple model and advanced to more complex ones to address the key issues. They now plan to produce a more detailed picture with still-more sophisticated models. They are also working to suggest experimental campaigns that will expose these new effects. Support for this research comes from the DOE Office of Science. Explore further: Team wins major supercomputer time to study the edge of fusion plasmas More information: A. H. Reiman et al, Suppression of Tearing Modes by Radio Frequency Current Condensation, Physical Review Letters (2018). DOI: 10.1103/PhysRevLett.121.225001
Scientific Luminaries See Great Potential for Grown DiamondsDynamic discussion, hosted by IIa Technologies, aims to bring grown diamond industry to greater heights SINGAPORE, Jan. 30, 2015 /PRNewswire/ -- Singapore-based IIa Technologies , a global leader in diamond growing technologies, recently hosted a roundtable meeting, ' The Future of Grown Diamonds ' on grown diamonds technologies and their potential across hi-technology industries. The closed-door meeting was attended by 14 eminent scientists and professors working and researching on diamond technologies-based applications. IIa Technologies was represented by its Chief Technology Officer, Dr Devi Shanker Misra. The gathered intelligentsia from top universities across US, Belgium, Russia and Taiwan agreed that the grown diamond industry is poised for greater success. Among the topics discussed, the group deliberated on the present practice of using the terminology 'synthetic' to describe grown diamonds. It was generally agreed that the term 'synthetic' is technically and scientifically incorrect. During our discussion, with regards to the definition of the Chemical Vapour Deposition (CVD) process and diamonds grown using the process, the overall consensus was that a more accurate descriptor would be grown diamonds as the physical and chemical properties of a grown and mined diamond are congruent, said Dr Misra, CTO of IIa Technologies. It was also felt that there was a need to improve the quality and size of grown diamonds so as to extend their usage across a range of scientific applications. Held during the 2014 Materials Research Society's (MRS) Fall Meeting and Exhibit in Boston, Massachusetts, the roundtable meeting was centred on the latest scientific developments, milestones and challenges of the grown diamond world. One such important milestone was achieved by IIa Technologies in Sept 2014, when it announced the creation of large size (7.5 mm x 7.5 mm) high quality, single crystal diamond plates of unsurpassed quality after 8 years of extensive research. The breakthrough opened up unprecedented opportunities for use in highly versatile applications such as radiation dosimeter used in cancer therapy, X-Ray detectors, X-Ray dosimeters, high power electronic devices and various other sophisticated technological devices. Dr Misra said , We have a research-led approach at IIa Technologies and are currently working to develop larger diamond plates, 15mm x 15mm, twice the current dimensions, for single crystal diamonds. Our goal is to not only raise the quality of the plates but also keep it cost-effective. Larger diamond plates will enable making integrated electronic high power and high frequency circuits on diamonds, leading to potential breakthroughs in using diamonds for electronics. Following the success of this first roundtable meeting, IIa Technologies plans to host several such discussion forums in the near future with reputed scientists and professors who are interested in the grown diamond field.
4th Asia-Pacific Transport Working Group Meeting (APTWG) Dear colleagues, I am very happy to inform you that the 4th Asia-Pacific Transport Working Group Meeting (APTWG) will be held from June 10 to June 13, 2014 at Chikushi Campus, Kyushu University in Fukuoka, Japan. The meeting website will be available soon. Here I would like to let you know basic information about the meeting. If you need any further information and clarification, please e-mail to aptwg2014@nifs.ac.jp . 1. Date: June 10 (Tue) －13 (Fri), 2014. 2. Venue: C-CUBE in Chikushi Campus of Kyushu University (No.22 in http://www.kyushu-u.ac.jp/access/map/ch ... shi-e.html ) 3. Registration fee: 15,000 JPY for regular participants 10,000 JPY for students 5,000 JPY for accompanying persons 4. Important dates: 11 April Deadline for VISA application 02 May Abstract submission deadline 16 May On-line registration deadline 5. Registration and VISA application Each of registration and VISA application will be done through an on-line service. The web pages for those will be available soon. Necessary information for the VISA is as follows; Name, Birthdate, Age, Nationality, Affiliation, Position, Address, Zip-code, Country, Telephone number, Fax number, E-mail address, Flight schedule (To/From Japan, Flight number, Departure/Arrival(Airport, Date(YYYY/MM/DD), Time(HH24/MI))), Itinerary (Date(YYYY/MM/DD), Travel schedule, Accommodation) Please get an early start on gathering information for VISA application if you would like to join the APTWG conference. 6. Meeting Structure Special Plenary Topical Contributed Sessions Working Group Sessions A. Turbulence suppression and transport barrier formation B. Effect of magnetic topology on MHD activity and transport C. Non-diffusive contribution of momentum and particle transport D. Non-local transport and turbulence spreading and coupling E. Energetic particles and instability Poster Sessions Young Researcher’s Forum Summary Sessions The Conference organizers greatly encourage your participation and submission of abstracts for this meeting. We will bring you the up-to-date information on this meeting by e-mail. Sincerely yours. Shigeru Inagaki and Naoki Tamura (Local Organizers) on behalf of Conference Organizeres
The 8th International West Lake Symposium – Laser Plasma Interactions (IWLS-LPI 2014) will be held at Hangzhou, China, April 21-25, 2014. IWLS-LPI 2014 will be hosted by the Institute for Fusion Theory and Simulation (IFTS), Zhejiang University. The mission of IFTS, established in 2006, is to carry out cutting-edge research in fusion, space, and other plasma physics. Significant advances have recently been made in the high-intensity short-pulse laser technology. The availability of tera- and peta-watt lasers has opened up the relativistic laser-plasma interaction regime and led to many new concepts and promising applications. The upcoming ten-petawatt lasers would certainly further enhance the interest in laser-plasma interactions. Numerical simulation of the extreme dynamics involved is also challenging. IWLS-LPI 2014 calls for current research results and discussions on the following topics: Novel radiation sources Advanced particle accelerators Laser-driven nuclear fusion Radiation reaction effects Computational plasma physics Laser-plasma applications http://ifts.zju.edu.cn/lpi/index.php
* Nature # Science(China) Science SciAm ( Top journal) Journal （单击可链接到杂志网站） 2012 IF About the Journal（投稿领域） Optical Society of America (OSA) Applied Optics 1.689 A highly regarded, premium quality must read for everyone in the optics field that offers applications-centered research in optics, photonics, imaging, and sensing. Topics germane to the journal include optical technology, lasers, photonics, environmental optics, and information processing. 3 issues per month Applied Spectroscopy 1.663 Applied Spectroscopy covers applications in analytical chemistry, materials science, biotechnology, and chemical characterization. Monthly issues Chinese Optics Letters 0.968 Chinese Optics Letters (COL) is one of the leading journals for optics in China. Published in English, it promotes the generation, application, and archiving of knowledge in all fields of optics. Monthly issues Journal of Lightwave Technology 2.555 The Journal of Lightwave Technology (JLT) contains theoretical and experimental papers on such topics as fiber and cable technologies; active and passive guided wave components such as light sources, detectors, repeater, switches, and fiber sensors; integrated optics and optoelectronics, systems, and sub-systems, networks; and switching. JLT is a joint publishing effort of the IEEE and OSA. J. Opt. Soc. Am. A 1.665 The Journal of the Optical Society of America A (JOSA A) is devoted to developments in any field of classical optics, image science, and vision. JOSA A includes original peer-reviewed papers on such topics as atmospheric optics, clinical vision, coherence and statistical optics, color, image processing, machine vision, scattering, and visual optics. Monthly issues J. Opt. Soc. Am. B 2.210 The Journal of the Optical Society of America B emphasizes scientific research on the fundamentals of the interaction of light with matter such as quantum optics, nonlinear optics, and laser physics. Topics include atom optics and cold atoms, metamaterials, nanophotonics, photonic crystals, spectroscopy, THz optics, ultrafast phenomena, and other related subjects. J. Opt. Soc. Korea 1.022 The Journal of the Optical Society of Korea (JOSK) publishes papers reporting recent advances, state-of-the-art research and development results in all areas of optical science and technology. JOSK is published in English by the Optical Society of Korea (OSK) and is made available through OSA's Optics InfoBase. Bi-monthly issues J. Opt. Technol. 0.245 The Journal of Optical Technology (JOT) is an English-language translation of the Russian journal, Opticheskii Zhurnal, which originates from the S.I. Vavilov State Optical Institute. JOT publishes design details of a diversity of optical instruments, along with a strong section on computational optics useful to engineers, mathematicians, and physicists, as well as optical scientists. Monthly issues Opt. Mater. Express 2.616 Optical Materials Express is OSA's newest all-electronic, open-access optics journal. The journal primarily emphasizes advances in novel optical materials, their properties, modeling, synthesis and fabrication techniques; how such materials contribute to novel optical behavior; and how they enable new or improved optical devices. monthly issues Optics Express 3.546 The original all-electronic, open-access optics journal, Optics Express (OpEx) is known for its rapid time to publication and high Impact Factor. OpEx publishes peer-reviewed articles that emphasize scientific and technology innovations in all aspects of optics and photonics. Bi-weekly issues Optics Letters 3.385 Optics Letters (OL) provides rapid dissemination of new results in all areas of optics and photonics with short, original, peer-reviewed communications. The articles often describe research-in-progress, thus reflecting the leading edge in the science of light. With an ISI Impact Factor of 3.399, OL is among the top-ranked journals in the Optics category. issues twice monthly Photonics Research (New in June 2013) 0 The Optical Society (OSA) and the Chinese Laser Press (CLP) have partnered to launch a new peer-reviewed journal publishing theoretical and applied research progress in optics and photonics.Photonics Research will debut in June 2013. Bi-monthly issues American Institute of Physics (AIP) Appl.Phys.Lett . 3.794 Applied Physics Letters, published by the AIP Publishing LLC, features concise, up-to-date reports on significant new findings in applied physics. Emphasizing rapid dissemination of key data and new physical insights, Applied Physics Letters offers prompt publication of new experimental and theoretical papers bearing on applications of physics phenomena to all branches of science, engineering, and modern technology. Content is published online daily, collected into weekly online and printed issues (52 issues per year). J.Appl. Phys. 2.210 Journal of Applied Physics is an influential international journal publishing significant new experimental and theoretical results of applied physics research. The journal also publishes special collections focusing on research of particular current or emerging interest. A key component of this journal is Applied Physics Reviews—these articles vary in scope and length from relatively short but authoritative state-of-the-art summaries to comprehensive, critical, monograph-length reviews. AIP Advances 1.349 AIP Advances is a fully open access, online-only community-led journal, covering all areas of applied physical science, including those topics not currently covered by the existing AIP journals. As an open access journal with advanced web 2.0 tools, the global research community will be able to find, share, evaluate, and discuss scientific research in new ways. AIP Advances puts relevant content and discussion tools in the hands of the community to shape the direction of the physical sciences. APL Materials 0 APL Materials is a new journal which will feature original research on significant topical issues within the field of materials science. Emphasis is given in the quality and timeliness of the publications, in order to highlight ongoing cutting-edge science. Content is published online daily, collected into monthly online issues (12 issues per year). (2013 年第一期 ) American Physical Society (APS) Phys.Rev. Lett. 7.943 PRL featured short, important papers from all branches of physics, and quickly assumed a place among the most prestigious publications in any scientific discipline. Today PRL is the world's foremost physics letters journal, providing rapid publication of short reports of significant fundamental research in all fields of physics. International in scope, the journal provides its diverse readership with weekly coverage of major advances in physics and cross disciplinary developments. PRL's topical sections are devoted to general physics (including statistical and quantum mechanics, quantum information, etc.), gravitation and astrophysics; elementary particles and fields; nuclear physics; atomic, molecular, and optical physics; nonlinear dynamics, fluid dynamics, classical optics; plasma and beam physics; condensed matter; and soft-matter, biological, and interdisciplinary physics. Phys.Rev.A 3.024 Physical Review A (PRA) provides a dependable resource of worldwide developments in the rapidly evolving area of atomic, molecular, and optical physics and related fundamental concepts. The journal contains articles on quantum mechanics including quantum information theory, atomic and molecular structure and dynamics, collisions and interactions (including interactions with surfaces and solids), clusters (including fullerenes), atomic and molecular processes in external fields, matter waves (including Bose-Einstein condensation), and optics, both quantum and classical. Phys.Rev.B 3.767 Physical Review B is the largest and most comprehensive international journal specializing in condensed matter and materials physics, publishing important papers on a wide range of topics Institute of Physics (IOP) Chinese Physics B 1.148 Chinese Physics B covers the latest developments and achievements in all branches of physics. Chinese Physics Letters 0.811 Chinese Physics Letters provides rapid publication of short reports and important research in all fields of physics. EPL (Europhysics Letters) 2.260 EPL publishes original, high-quality Letters in all areas of physics, ranging from condensed matter topics and interdisciplinary research to astrophysics, geophysics, plasma and fusion sciences, including those with application potential. Articles must contain sufficient argument and supporting information to satisfy workers in the field, and must also be of interest and relevance to wider sections of the physics community. Journal of Optics 1.990 Serving the whole of the optics community, Journal of Optics covers all aspects of research within modern and classical optics. Journal of Physics B: Atomic, Molecular and Optical Physics 2.031 Journal of Physics B: Atomic, Molecular and Optical Physics covers the study of atoms, ions, molecules and clusters, and their structure and interactions with particles, photons or fields. Nanotechnology 3.842 Nanotechnology encompasses the understanding of the fundamental physics, chemistry, biology and technology of nanometre-scale objects. New Journal of Physics 4.063 New Journal of Physics publishes across the whole of physics, encompassing pure, applied, theoretical and experimental research, as well as interdisciplinary topics where physics forms the central theme. All content is permanently free to read and the journal is funded by an article publication charge. Elsevier Photonics and Nanostructures - Fundamentals and Applications 1.792 This journal establishes a dedicated channel for physicists, material scientists, chemists, engineers and computer scientists who are interested in photonics and nanostructures, and especially in research related to photonic crystals, photonic band gaps and metamaterials. The Journal sheds light on the latest developments in this growing field of science that will see the emergence of faster telecommunications and ultimately computers that use light instead of electrons to connect components. Optics and Lasers in Engineering 1.916 Optics and Lasers in Engineering aims to provide an international forum for the interchange of information on the development and application of optical techniques and laser technology in engineering. Emphasis is placed on contributions dealing with the practical use of methods and devices, the evaluation of results and developments and enhancement of solutions and new theoretical foundations for experimental methods. Optical Materials 1.918 Optical Materials ： An International Journal on the Physics and Chemistry of Optical Materials and their Applications, including Devices. The purpose of Optical Materials is to provide a means of communication and technology transfer between researchers who are interested in materials for potential device applications. The journal publishes original papers and review articles on the design, synthesis, characterisation and applications of optical materials. OPTICAL MATERIALS focuses on: Optical Properties of Material Systems; The Materials Aspects of Optical Phenomena; The Materials Aspects of Devices and Applications. Optics Laser Technology 1.365 Optics Laser Technology aims to provide a vehicle for the publication of a broad range of high quality research and review papers in those fields of scientific and engineering research appertaining to the development and application of the technology of optics and lasers. Papers describing original work in these areas are submitted to rigorous refereeing prior to acceptance for publication. Optics Communications 1.438 Optics Communications considers only original and timely contributions containing new results in various fields of modern optics. Manuscripts may discuss fundamental or applied issues, and should offer clear evidence of novelty and significance. Papers devoted, for the most part, to mathematical and computational issues, with limited direct connection to current trends of optics research, are generally not suitable for publication in the Journal. Similarly, small technical advances, or papers concerned only with engineering applications or issues of materials science may not be considered favourably. Optik 0.524 Optics design, geometrical and beam optics, wave optics Optical and micro-optical components, diffractive optics, devices and systems Photoelectric and optoelectronic devices Optical properties of materials, nonlinear optics, wave propagation and transmission in homogeneous and inhomogeneous materials Information optics, image formation and processing, holographic techniques, microscopes and spectrometer techniques, and image analysis Optical testing and measuring techniques Optical communication and computing Physiological optics As well as other related topics. Springer Optical and Quantum Electronics 0.987 Optical and Quantum Electronics publishes papers on the following topics: semiconductors, solid state and gas lasers, optical communication systems, fibres and planar waveguides, non-linear optics, optoelectronic devices, ultra-fast phenomena, optical storage, optical materials, photonic switching, optics in computers and coherent optics. Photonic Sensors EI Photonic Sensors is a peer-reviewed open access journal published under the brand SpringerOpen. It presents original, peer-reviewed articles that report on new developments of interest to members of the photonics and sensor communities in all fields of photonic sensing science and technology. The journal's coverage includes optical fiber sensors, planar waveguide sensors, laser-based sensors, and biophotonic sensors and more. Photonic Sensors focuses on experimental contributions related to novel principles, structures or materials for photonic sensors. Plasmonics 2.425 Coverage includes theory, physics, and applications of surface plasmons in metals, and rapidly emerging areas of nanotechnology, biophotonics, sensing, biochemistry and medicine. The journal covers the theory, synthesis and optical properties of noble metal nanostructures, patterned surfaces, continuous or grated surfaces and devices. Applications include surface-enhanced spectroscopic properties, such as Raman scattering or fluorescence, as well developments in techniques such as surface plasmon resonance and near-field scanning optical microscopy. Applied Physics B 1.782 Applied Physics B covers the broad field of laser physics, linear and nonlinear optics, ultrafast phenomena, photonic devices, optical and laser materials, quantum optics, laser spectroscopy of atoms, molecules and clusters, and use of laser radiation in biophotonics, chemistry and biochemistry Journal of Optics EI The Journal of Optics publishes research papers on results of original and applied research of sufficient merit in all branches of optical physics and technology such as science of vision, colour, photometry, illumination, optical/opto-electronic materials and devices, optical testing and standardisation, spectroscopy, lasers, holography, fibre optics, non-linear optics, optical and opto-electronic systems and instruments, image processing, optical computing etc. Review articles and literature citations on various aspects of optics are also welcome. Nano Research 7.392 Synthesis, characterization and manipulation of nanomaterials; Nanoscale physics, electrical transport, quantum physics; Scanning probe microscopy and spectroscopy; Nanofluidics; Nanosensors; Nanoelectronics and molecular electronics; Nano-optics, nano-optoelectronics and nano-photonics; Nanomagnetics; Nanobiotechnology and nanomedicine; Nanoscale modeling and simulations. Journal of Infrared, Millimeter, and Terahertz Waves 1.120 The Journal of Infrared, Millimeter, and Terahertz Waves offers a peer-reviewed platform for the rapid dissemination of original, high-quality research in the frequency window from 30 GHz to 30 THz. The topics covered include: sources, detectors, and other devices; systems, spectroscopy, sensing, interaction between electromagnetic waves and matter, applications, metrology, and communications. Manuscripts submitted to the Journal should discuss a significant advancement to the field of infrared, millimeter, and terahertz waves. Journal of Nanoparticle Research 2.175 The Journal of Nanoparticle Research is a monthly peer-reviewed journal that explores the specific concepts, properties, phenomena and processes of structures at the nanoscale size range. Coverage includes synthesis, assembly, transport, reactivity, and stability, and emphasizes realization and application of systems, structures and devices with novel functions obtained via precursor nanoparticles. Frontiers of Optoelectronics 0 Frontiers of Optoelectronics seeks to provide a multidisciplinary forum for a broad mix of peer-reviewed academic papers in order to promote rapid communication and exchange between researchers in China and abroad. It introduces and reflects significant achievements being made in the field of optoelectronics. Its coverage includes most main branches of optoelectronics and some aspects of optics. Science China Physics, Mechanics and Astronomy 1.169 Research papers report on important original results in all areas of physics, mechanics and astronomy. Frontiers of Physics 1.591 The journal spans a wide range of topics, reporting experiments, techniques and ideas that advance the understanding of physics worldwide. Among the fields covered are physics of quantum mechanics and quantum information; gravitation, cosmology and astrophysics; elementary particles and fields; nuclear physics; atomic, molecular and optical physics; statistical and nonlinear physics; plasma physics and accelerator physics; condensed matter physics; nanostructures and functional materials; and soft matter, biological physics and interdisciplinary physics. Nanoscale Research Letters 2.524 Nanoscale Research Letters (NRL) is a peer-reviewed open access journal published under the brand SpringerOpen. It is providing an interdisciplinary forum for communication of scientific and technological advances in the creation and use of objects at the nanometer scale. The journal spans disciplines, emphasizing research that seeks to uncover the underlying science and behavior of nanostructures and further the goal of unifying nanoscale research in physics, materials science, biology, chemistry, engineering, and their expanding interfaces. Original research papers which appear rapidly following submission are published as Nano Express. Nano Ideas is a new format that focuses on well-founded and conceptually substantiated ideas which need neither elaborate theoretical verification nor experimental realization. NRL also publishes invited personal perspectives as Nano Commentaries, addressing general concerns of the nano community and highlighting new areas of science. Optics and Spectroscopy 0.559 Optics and Spectroscopy (Optika i spektroskopiya), founded in 1956, presents original and review papers in various fields of modern optics and spectroscopy in the entire wavelength range from radio waves to X-rays. Topics covered include problems of theoretical and experimental spectroscopy of atoms, molecules, and condensed state, lasers and the interaction of laser radiation with matter, physical and geometrical optics, holography, and physical principles of optical instrument making. Optoelectronics Letters EI he purpose of this journal is to promote international academic exchange in the fields of Photonics and Optoelectronics in China and abroad, through the rapid reporting of new and important experimental results. This journal represents an important window into Chinese science and technology in the field of photonics and optoelectronics. Coverage includes new functional materials and devices; micro– nano– structure and quantum optoelectronics; optoelectronics information technology; sensing, measurement and inspection; storage and display; image and information processing. Optical Review 0.702 Optical Review is an international journal presenting top results in optical science and technology. The scope of the journal includes general and physical optics; quantum optics and spectroscopy; information optics; photonics and optoelectronics; lasers; nonlinear optics; optical systems and technologies; optical materials and manufacturing technologies; environmental, biological and space optics; vision; infrared and short wavelength optics; and other optical methods and applications American Chemical Society （ ACS ） Nano Letters 13.025 ano Letters reports on fundamental research in all branches of the theory and practice of nanoscience and nanotechnology, providing rapid disclosure of the key elements of a study, publishing preliminary, experimental, and theoretical results on the physical, chemical, and biological phenomena, along with processes and applications of structures within the nanoscale range. Among the areas of interest the journal covers are: Synthesis and processing of organic, inorganic, and hybrid nanosized materials by physical, chemical, and biological methods Modeling and simulation of synthetic, assembly, and interaction processes Characterization of size-dependent properties Realization and application of novel nanostructures and nanodevices ACS Nano 12.062 ACS Nano publishes comprehensive articles on synthesis, assembly, characterization, theory, and simulation of nanostructures (nanomaterials and assemblies, nanodevices, and self-assembled structures), nanobiotechnology, nanofabrication, methods and tools for nanoscience and nanotechnology, and self- and directed-assembly. The Journal of Physical Chemistry C 4.814 The Journal of Physical Chemistry C (Energy Conversion and Storage, Optical and Electronic Devices, Interfaces, Nanomaterials, and Hard Matter) publishes studies on energy conversion and storage; energy and charge transport; surfaces, interfaces, porous materials, and catalysis; plasmonics, optical materials, and hard matter; physical processes in nanomaterials and nanostructures. The Journal of Physical Chemistry Letters 6.585 ournal of Physical Chemistry Letters covers all topic areas currently included in Journal of Physical Chemistry A, B, and C. Institute of Electrical and Electronics Engineers （ IEEE ） Photonics Technology Letters 2.038 Original contributions are welcome which relate significant advances or state-of-the-art capabilities in the theory, design, fabrication, application, or performance of-- Semiconductor optical devices; -- Optical fiber and waveguide technologies -- Optical filters, control, and switching devices; -- Free-space and fiber-optic transmission systems and subsystems; -- Optical sensors; including bio-photonics, remote sensing, fiber-optic gyroscopes, etc. -- Other photonic technologies; including THz waves, plasmons, etc. Photonics Journal 2.356 IEEE Photonics is an online-only rapid publication archival journal of top quality research at the fore-front of Photonics. Photonics integrates quantum electronics and optics to accelerate progress in the generation of novel photon sources and in their utilization in emerging applications at the micro and nano scales spanning from the far infrared/THz to the x-ray region of the electromagnetic spectrum. Original short and full length contributions to IEEE Photonics are welcome. Contributions can address issues ranging from fundamental understanding to emerging technologies and applications. Optoelectronics 0.849 IET Optoelectronics covers but is not limited to the following topics: Optical and optoelectronic materials; Light sources, including LEDs, lasers and devices for lighting; Optical modulation and multiplexing; Optical fibres, cables and connectors; Optical amplifiers; Photodetectors and optical receivers; Photonic integrated circuits; Nanophotonics and photonic crystals; Optical signal processing; Holography; Displays. Society of Photo-Optica lInstrumentation Engineers (SPIE) Optical Engineering 0.88 Optical Engineering publishes papers reporting on research and development in optical science and engineering and the practical applications of known optical science, engineering, and technology. Journal of Nanophotonics 1.644 The Journal of Nanophotonics (JNP) is an electronic journal focusing on the fabrication and application of nanostructures that facilitate the generation, propagation, manipulation, and detection of light from the infrared to the ultraviolet regimes. The scope extends to theory, modeling and simulation, experimentation, instrumentation, and application Journal of Photonics for Energy 1.00 The Journal of Photonics for Energy (JPE) is an e-journal that covers fundamental and applied research areas focused on the applications of photonics for renewable energy harvesting, conversion, storage, distribution, monitoring, consumption, and efficient usage Other journals Journal of Modern Optics 1.163 General topics covered include: • Optical and photonic materials (inc. metamaterials) • Plasmonics and nanophotonics • Quantum optics (inc. quantum information) • Optical instrumentation and technology (inc. detectors, metrology, sensors, lasers) • Coherence, propagation, polarization and manipulation (classical optics) • Scattering and holography (diffractive optics) • Optical fibres and optical communications (inc. integrated optics, amplifiers) • Vision science and applications • Medical and biomedical optics • Nonlinear and ultrafast optics (inc. harmonic generation, multiphoton spectroscopy) • Imaging and Image processing Welcome to add the other optical journal! Email:junqiaowang@126.com 也可以访问： http://teachers.zzu.edu.cn/teacher/Default.aspx?tabid=21107ctl=Detailmid=22246aid=1378language=zh-C N ——————————
Dear Colleagues, the 20th International Conference on Gas Discharges and their Applications will be held in Orléans from July 6 to July 11, 2014. The abstract submission is now open. Please follow the instructions given on the conference website and submit your contribution before October 15. The list of Invited Speakers is available here For any other information, please visit GD2014 website http://gd2014.sciencesconf.org/ or contact us at gd2014@sciencesconf.org We are looking forward to seeing you in Orléans next year. The Local Organizing Committee Dunpin Hong, Chair of GD2014 Maxime Mikikian, Secretary Jean-Marc Bauchire, Program Chair Hervé Rabat, Coordinator It is a great pleasure to invite you to take part in the 20 th International Conference on Gas Discharges and their Applications , which is to be held in Orleans, France, and exceptionally in July (from 6th to 11th) instead of September. We are confident that this conference, like previous editions, will be a forum of discussion for our community. All aspects of electrical discharges will be explored from advanced models to emerging applications . We expect that new challenges and recent breakthroughs in this field will be presented during this conference. We will update this website with lots of information about the conference, as well as practical information about travel and accommodation. If you need additional information, do not hesitate to contact us at gd2014@sciencesconf.org . We are looking forward to welcoming you together with your guests in Orleans in July 2014. We hope you will enjoy the scientific presentations and the atmosphere of our city along the royal Loire River. Local Organizing Committee Dunpin HONG (Chairman), Maxime MIKIKIAN, Jean-Marc BAUCHIRE, Hervé RABAT
Increasing applications of chemical vapour deposited (CVD) diamond have raised the need for efficient and robust microwave plasma reactors which are optimized for the large area deposition of diamond films and wafers. On the basis of extended numerical simulations Fraunhofer IAF has developed a novel microwave plasma CVD technology. An ellipsoidal cavity is used to focus the microwave energy into an intense and extended plasma. These ellipsoidal plasma reactors exhibit a combination of beneficial properties including Large area deposition: homogeneous deposition of CVD diamond on 3 (2.45 GHz) and 6 (915 MHz) substrates possible. Stability: Long-term operation possible, no plasma instabilities. Versatility: The reactor can be run under various conditions (pressure, power etc.). Growth of high-purity diamond: Properties of CVD diamond disks are identical to those of perfect single diamond crystals. This patented reactor technology has been successfully commercialized. The two figures show ellipsoidal plasma reactors which are fully computer controlled and equipped with all the safety units necessary for the operation in an industrial environment. The reactors are operated at 2.45 GHz, 6 kW (upper figure) and 915 MHz, 30-60 kW (lower figure), respectively. 东西绝对是好东西，价格也绝对的好！呵呵！ 英文不好不是偶的错，希望大家看的开心。有兴趣可以加入“人造金刚石”QQ群： 152384182
Diamonds - Rapid Production of Synthetic Diamonds Using a Plasma Jet Reactor Topics Covered Overview Background Microwave Production of Synthetic Diamonds Using A Plasma Jet Reactor to Increase Deposition Rates Improving The Process Overview A plasma jet reactor is used in place of the conventional microwave reactor to speed up artificial diamond synthesis by 10-100 times. Diamond layers are used for wear-resistant coatings, infrared cameras, drill bits and laser diodes. Background For the past 20 years scientists have successfully been making thin films of ‘artificial’ diamond in the laboratory by a process called chemical vapour deposition (CVD). Applications for such material include tough coatings for drill bits, windows for infrared cameras such as those used to detect survivors buried in rubble after earthquakes and heat dissipators for high power electronic components like laser diodes. Now, Professor Mike Ashfold and his team in the School of Chemistry at the University of Bristol and De Beers Industrial Diamonds, are unravelling some of the complex chemistry involved in the rapid growth of diamond films. Microwave Production of Synthetic Diamonds Diamond is a form of carbon and in nature it is usually found as single crystals. However, CVD diamond is ‘polycrystalline’ – it consists of many very small crystals fused together. One way of making polycrystalline diamond in the laboratory is to place a mixture of methane (which contains the carbon) and hydrogen in a microwave reactor. The microwave energy splits the hydrogen into highly reactive atoms which, in turn, react with the methane, generating reactive carbon-containing molecular fragments called radicals. This gas mixture, which also includes many electrically charged or ionised species is called a plasma. The carbon-containing radicals alight on the material that is to be coated and given the right conditions, the carbon atoms form the appropriate chemical bonds to create crystalline diamond. Using A Plasma Jet Reactor to Increase Deposition Rates “In this way it takes about an hour to make a layer of diamond a micrometre thick,” says Professor Mike Ashfold. “For making wear-resistant coatings, one might typically want a layer tens of micrometres thick; for a window on an infrared camera millimetre-thicknesses would be preferable.” One way to accelerate the process is to use a device called a plasma jet reactor. A jet of argon plasma is passed at high velocity through an aperture of about 2 millimetres in diameter. Hydrogen and methane are added. The system produces a very high velocity jet of plasma at very high temperature. The plasma jet offers a brute force approach: the gas pressures and flow rates are higher, and the power input is larger, resulting in diamond film growth at rates 10-100 times greater than with the microwave reactor. However, the crystalline quality is generally less good. Improving The Process Now, using sophisticated spectroscopic techniques the team has been able to map the concentrations of various of the key carbon-containing species within the plasma jet in order to gain a better understanding of the process, and thereby optimise the experimental conditions needed to produce higher quality diamond layers at many times the rate of conventional systems. Source: The Engineering and Physical Sciences Research Council. 原文出自： http://www.azom.com/article.aspx?ArticleID=2207 英文不好不是偶的错，希望大家看的开心。有兴趣可以加入“人造金刚石”QQ群： 152384182
Frost Sullivan: MPCVD Diamonds - Challenging the next frontier for technologyConsistent availability of high-quality diamonds to benefit gem, scientific high-tech applications SYDNEY, April 22, 2013 /PRNewswire/ -- The microwave plasma chemical vapor deposition (MPCVD) diamond growth process has witnessed significant technological advancements, widening the prospects of lab-grown diamonds in gem applications as well as in scientific and high-tech applications. While the MPCVD technique has been used over the last decade to successfully grow small single crystal, colorless diamonds at various research facilities around the world in a limited scale for scientific studies, scalable growth of consistent quality diamonds has been almost impossible to achieve. New analysis from Frost Sullivan ( http://www.industrialautomation.frost.com ), Grown Diamonds - Shaping the Future Of the Diamond Industry , finds that leading industry firms have now been able to integrate high-end research with effective management of formidable supply-chain and cost-related challenges, enabling the scalable production of high-quality, single-crystal, colorless lab-grown diamonds. Mr. Tom Chatham, Chatham Created Gems Diamonds Inc. notes that success in scaling-up production of diamonds using CVD technology requires scientific know-how, continuous flow of funds and a passion for years of research. There are several aspects - and not all are related to Chemistry - that need to be optimized in order to achieve successful continuous production. Like any new and potentially disruptive technology, MPCVD grown diamonds have been perceived both as an opportunity and as a threat. As a direct consumer product, the challenge faced by the grown diamond industry is to eliminate terminologies aimed at reducing its acceptability and to educate consumers about the reality and benefits of grown diamonds. In scientific and high technology applications, consistent supply and commercial viability will lead to rapid uptake. The confusion in terminology of grown diamonds may have an impact on end-buyers in the gem application market, noted Mr. Mike McMahon, CEO of SCIO Diamond Technology Corporation. In this regard, marketing campaigns and a consortium message from industry participants that comprehensively cover the benefits of lab-grown diamonds would be a welcome step. He goes on to add that for the customers in scientific high-tech applications, consistent availability of diamonds suited to their particular applications is paramount. Industry participants will be able to overcome these challenges by effective marketing campaigns that increase awareness of grown diamonds among consumers. MPCVD doesn't involve synthesis at any stage of the diamond growth process, and leads to the formation of diamond in its native element form, just like earth-derived diamonds. Grown MPCVD diamonds, unlike diamond simulants such as Moissanite, are identical to earth-derived diamonds in terms of physical, chemical and optical properties. In fact, these diamonds are high-quality Type IIA diamonds, which is a very pure, very rare type of diamond, comprising less than two percent of the world's earth-derived diamonds. The report may be downloaded through registering at this link: http://www.frost.com/sublib/display-market-insight.do?id=276747662 For media queries or if you are interested in more information on this research, please send an email to djeremiah@frost.com Corporate Communications, at djeremiah@frost.com , with your full name, company name, job title, telephone number, company email address, company website, city, state and country. About Frost Sullivan Frost Sullivan, the Growth Partnership Company, works in collaboration with clients to leverage visionary innovation that addresses the global challenges and related growth opportunities that will make or break today's market participants. Our Growth Partnership supports clients by addressing these opportunities and incorporating two key elements driving visionary innovation: The Integrated Value Proposition and The Partnership Infrastructure. The Integrated Value Proposition provides support to our clients throughout all phases of their journey to visionary innovation including: research, analysis, strategy, vision, innovation and implementation. The Partnership Infrastructure is entirely unique as it constructs the foundation upon which visionary innovation becomes possible. This includes our 360 degree research, comprehensive industry coverage, career best practices as well as our global footprint of more than 40 offices. For more than 50 years, we have been developing growth strategies for the global 1000, emerging businesses, the public sector and the investment community. Is your organization prepared for the next profound wave of industry convergence, disruptive technologies, increasing competitive intensity, Mega Trends, breakthrough best practices, changing customer dynamics and emerging economies? Contact Us: Start the discussion Join Us: Join our community Subscribe: Newsletter on the next big thing Register: Gain access to visionary innovation Contact: Donna Jeremiah Corporate Communications, Asia Pacific D: +61 (2) 8247 8927 E: djeremiah@frost.com Carrie Low Corporate Communications, Asia Pacific D: +603 6204 5910 E: carrie.low@frost.com Jessie Loh Corporate Communications, Asia Pacific D: +65 6890 0942 E: jessie.loh@frost.com 原文出自： http://finance.yahoo.com/news/frost-sullivan-mpcvd-diamonds-challenging-025100296.html;_ylt=AwrNUbBKboxRy2gAckzQtDMD 英文不好不是偶的错，希望大家看的开心！有兴趣可以申请加入QQ群： 152384182（人造金刚石），单纯刷广告的不太欢迎！
据 Phys.Org 网 站 2013 年 1 月 13 日 报道， 英国曼彻斯特大学（ University of Manchester ）的研究人员已经发现，利用神奇材料石墨烯可以帮助检测体内是否存在毒品或毒素，可以显著改善机场安全问题。英国曼彻斯特大学的研究人员与来自法国 Aix-Marseille 大学（ Aix-Marseille University ） 的科学家合作， 已经创建了一种通过一个简单的光学系统，会潜在地看到一个分子的装置，能在几分钟内完成对其组成的分析。这种快速分析技术使用了表面等离子体激元学（ plasmonics ），也称之为表面电浆光学，是奈米光学领域最重要的议题而且也是电浆物理研究的最新领域，研究在不同材料中电子的振动。这项突破可能会允许快速和更准确地对职业运动员是否服用兴奋剂等违纪药品进行测试 , 因为这种技术能察觉到甚至存在是微量的某种物质。它也可以用在机场或其他戒备森严的场所以防止潜在的恐怖分子隐藏爆炸物或者利用人体走私毒品。另一个可能的使用就是检测人体可能感染的病毒。更多信息请浏览：《自然材料》（ Nature Materials ） 杂志网站的相关文献： More information: " Singular phase nano-optics in plasmonic metamaterials for label-free single-molecule detection, " by V. G. Kravets, F. Schedin, R. Jalil, L. Britnell, R. V. Gorbachev, D. Ansell, B. Thackray, K. S. Novoselov, A. K. Geim, A. V. Kabashin and A. N. Grigorenko, Nature Materials , 2013.
回旋动理学应该是我们做磁约束等离子体理论的基本工具，可惜到今天为止我还没有看懂过一篇回旋动理学的文章， 请教了Xu师弟后，他给了我以下建议： "建议先看Brizard在07年review of modern physics上写的一篇综述。他是基于李变换扰动方法的现代回旋动理学理论，这篇能看懂应该就能看懂大多数回旋动理学的文献了。李变换扰动方法可以看文献：Cary,1983,annal of physics，littlejohn,1982,journal of mathematical physics。最后一篇需要对微分流形有一些简单的了解。" 有懂的同学可以在这留言告诉我你的心得，谢谢！
王晓钢教授（科学网博主--等离子体科学）刚刚当选2011年美国物理学会会士(APS Fellow)，已肯定他在磁重联和复杂等离子体方面的贡献。这是继蔡诗东院士我国第二个等离子体物理学家在大陆获得的APS Fellow。证书上的嘉奖词（citation）是： “For seminal contributions to the theory of magnetic reconnection with broad applications to fusion and space plasmas, and to studies of waves and instabilities in complex plasmas.” 当选APS Fellow 还是很不容易的。 以前看过APS DPP的Fellow名单，发现只有L.CHEN, G.FU等几位华人在，大陆本土竟然一个都没有，太悲催了。9.16号刚刚在杭州CPS秋季会议上见过王老师。再次祝贺王老师，望大陆有更多人成为APS Fellow。
本文转自王晓钢的博客 磁重联漫谈 （1） 屈指数来，笔者研究等离子体中磁力线的“重联”现象已整整 20 年了。 磁重联（ magnetic reconnection ），或磁力线重联（ magnetic field line reconnection ）——也有叫“磁场重联”的，取描述磁力线“断开”（ break ）再“重新连接”（ reconnect ）的物理过程的意思。这一过程早期就是用 magnetic field line broken and reconnected 这样的语言来表述的。（既然是“连接”，应该译作“磁重连”的；不过既然大家都这么用着，就先这么写着。） 磁重联的理论，在实验室、空间、与天体等离子体物理领域里都有重要的应用。很多“快尺度”的大规模能量转换过程如实验室中磁约束等离子体的各种撕裂不稳定性（ tearing instabilities ）、空间物理中太阳风等离子体与地球磁层之间的耦合、天体（太阳）物理中耀斑（ solar flares ）、日冕加热（ solar coronal heating ）、日冕物质抛射（ coronal mass ejections, CME ）等现象，或是典型的、或是伴随着磁重联的物理过程。而且基于磁重联理论发展起来的“磁场拓扑”理论对几何与拓扑研究也有很大的推动。 磁重联的模型，起源于天体（太阳）物理的研究。最早的“磁重联”概念是一位澳洲的物理学家为解释日耀斑现象而提出的（ Giovanelli, R. G., 1946: Nature 158 , 81 ）。但是那时他用的 terminology 不是“ magnetic reconnection ”，而是“ magnetic annihilation ”——磁“湮灭”。就是说，当两条方向相反、相对运动的磁力线在一点“相遇”时，会产生磁“湮灭”而放出光——用此来解释日耀斑观测看到的强辐射。 这个简单的模型，开创了等离子体物理学的一个重要研究领域——磁重联理论、实验、与卫星、天文观测。以至于最近美国专门以磁重联研究为主要目的连续发射了五颗卫星（即所谓 THEMIS 计划）。什么叫“原创性研究”（ original work ）？ Giovanelli 的这个工作就是典型的例子。 当然，现在看来这个模型还非常粗糙。不过，开创性的工作常常是简单的、但是抓住了关键。 磁重联漫谈 （2） 当然，现在看来这个模型还非常粗糙。 首先，通过现代计算机模拟我们可以看到，磁力线的电磁“湮灭”是在真空中发生的现象。即磁力线只有在真空中才能以光速运动并“湮灭”。而在等离子体中，因为要“携带”环绕其旋转的带电粒子（特别是离子）一起运动，所以磁力线是有“质量”的，即使是电磁扰动引起的磁力线运动，其速度相比光速来说也是缓慢的——大约在 Alfven 速度的数量级。因此，后来人们改用“ reconnection ”来代替“ annihilation ”。 而且我们知道，磁场的散度为零，所以磁力线是不会“断开”的（至少在真空中）。实际上，在等离子体的理想磁流体（ ideal magnetohydrodynamics, or ideal MHD ）近似下，等离子体与磁力线是“冻结”（ frozen in ）在一起运动。形象地说，就如我们小时候喜欢吃的“棒冰”的冰冻结在中间的棍上一样。更准确的比喻是串在中间的杆儿上的算盘珠：可以很容易的沿着杆儿运动或者“回旋”运动，但是没法“跨越”这一根杆儿到另一杆儿上去。当然，如果等离子体中有不均匀性，还是会产生横越磁力线的“漂移”（ drift ），但是如果磁场限制在有限的体积内，这种“漂移”运动仍然限于同一磁力线所螺旋缠绕成的磁面上：不过是“抄近路”到同一磁力线的另一部分而已。就像调皮的孩子在螺旋滑梯上直线地从“一层”跳到“另一层”。 理想磁流体的这一重要性质可以用来实现在物理测量上“追踪”（ tracing ）磁力线（ A. Newcomb, 1960: Ann. Phys. (N.Y.) 10 , 232 ）；并且保证了磁力线在其演化过程中拓扑性质不变。这种不变性对应的守恒量叫做“磁螺旋度”（ magnetic helicity ），定义为磁矢势 A 与磁感应强度 B 的点乘积的空间积分（一般积分域为一条“磁力管”）。 当等离子体中的耗散效应（比如电阻）很小的时候，也就是说，磁力线在等离子体中的扩散时间远大于磁力线运动的特征时间、或者耗散效应起显著作用的特征空间尺度远小于磁场变化的特征空间尺度，上述性质还可以继续应用。所以对于空间以及实验室中的磁约束等离子体来说，理想磁流体的这些性质基本上都是适用的。 但是，当两条磁力线足够接近，到了“非理想”效应（ non-ideal effects ，比如耗散或者其它破坏理想磁流体条件的动理学效应如有限 Larmor 半径等效应）显著影响物理过程的尺度，随它们一起运动的“等离子体元”便分辨不出自己到底属于哪一条磁力线。这可以有两种情况：或者（当碰撞很弱的时候）两条磁力线之间的距离小于带电粒子环绕磁力线运动的回旋半径（ Larmor 半径）；或者（当碰撞足够强的时候）一条磁力线上的电子被“碰出”自己的回旋轨道后可以被另一条磁力线“捕获”，甚至完全“丢失”了（不知道跑到那条磁力线上去了）。 这时反过来我们也可以说（因为我们只能做粒子运动的测量）磁力线“丢失”了自己的 identity ，也就是说我们无法 identify 磁力线了。人们把这个磁力线“迷失”的区域叫做“扩散区”（ Diffusion Region ）。因此，在这个区域里磁场的拓扑可以发生改变。一旦这种改变发生，“走出”这个“扩散区”的磁力线就已经不再是原来的磁力线了。它们之间的连接形式发生了“重组”。我们把这个磁力线进入扩散区、“迷失”、重新连接，最后“走出”扩散区的整个过程，叫做“磁力线重联”或者简称“磁重联”。显然，磁重联伴随着磁场拓扑的变化（比如等离子体中的撕裂模就是一种典型的磁重联过程，“撕裂”就有原来磁场拓扑被改变的意思），因此导致磁场能量的快速释放。所以实验室、空间、天体等离子体中很多快过程、特别是“突发”（ Onset ）过程，如太阳耀斑、日冕物质抛射、磁暴（ Magnetic Storms ）、磁层亚暴（ Magnetosphere Substorms ）、锯齿崩塌（ Sawtooth Collapses ）、破裂不稳定性（ Disruptions ）等都与磁重联有关甚至是磁重联主导的物理过程。 磁重联漫谈 （3） 一场秋雨一场凉。终于告别炎热的夏天，迎来了秋季学期。校园里又充满了年轻人的欢声笑语。 周末，不谈学问，说点轻松的： 说起“磁螺旋度守恒”，想起在 Graduate School 的一些往事。 我的博士导师曾经对“磁螺旋度守恒”的发展做过一些贡献。前面说了磁螺旋度定义为磁矢势 A 与磁感应强度 B 的点乘积的空间积分。他名字的英文缩写正好是 A. B. ，所以一些同行戏称他“ A dot B ”（即 A 点乘 B 的英文读法）。我第一年上他的《流体物理》，有时会到办公室问些问题。当时读文献看到“磁螺旋度守恒”觉得挺有意思的，就去问： “物理学中的守恒量都对应着一种不变性。比如能量动量守恒对应时空平移不变性。那么 Helicity 守恒对应什么不变性？” 记得他当时扬了扬眉毛，看了我一下，不无赞叹地说：“中国的大学里还学这些？”暑假考过 Qualify 以后，他便鼓励我到他那里做，并建议我申请 JHU/APL 的 Fellowship ——大概相当于国内学校的“宝钢奖学金”一类的，但是条件很丰厚，比当时博士后的 salary 还多：因为包括了每年几万美元的学费。到我手里的 stipend 当然没有那么多，但是还是比学校助研奖学金（ Graduate Research Assistantship, GRA ）多不少。而且包括每年参加两次学术会议及论文版面费的研究经费。我在磁重联方面的工作，就是在这个 Fellowship 的支持下起步的。当然，现在翻出那时写的文章，会觉得很幼稚。可是当时写的时候，还是信心满满地，说：“一劳永逸地解决了”（ once for all ）某某问题。结果被 referee 狠狠地教训了一通 :p 那篇文章是关于地磁亚暴的，发在 JGR 上。接着做的是关于太阳物理的，发在 ApJ 上。再接下来却是一篇流体的（ finite time singularity ）、一篇磁约束聚变（ sawtooth crash ）的。没几年的时间，等离子体物理的主要领域都走了一遍，有点踌躇满志的感觉吧。直到毕业那一年在 Gordon Conference 上（第二年又在 UCSB 的 ITP ）与一位有名的前辈科学家 John Greene 深入讨论磁重联的基本概念，才知道我的一些理解不仅肤浅，有些甚至根本就是错误的。 在 New Hampshire 和 Santa Barbara 与 Greene 先生的那些讨论，让我受益至今。当时他就非常强调磁重联的零点，其重要性我到后来也才渐渐明白。前几年我们通过卫星观测数据分析得到了有关的证据，并看到了很多相关的物理现象。但是那时他已经失去记忆了。否则，有很多我至今仍想不明白的卫星观测结果在他那里一定会有清晰的答案。 Greene 先生在去年去世了。作为等离子体物理方面国际最高奖项之一 Maxwell 奖的得主（ 1992 ），他的名字通过“ BGK 波”留在了物理教科书上。但是，我个人认为，他在磁重联方面的贡献，也许更重要；至少应该不逊于著名的 Sweet-Parker 模型。他的 Maxwell 奖获奖报告就是关于磁重联拓扑理论的。与 Eugene Parker 教授一样，更可贵的是他对科学真理的不懈追求。记得他说过：他那些关于三维磁重联基本理论的文章送出去以后，每次一开始都被 Referee 们打了回来。提起这件往事他开玩笑说：每次 rejected ，他就再送。次数多了，那些人也 tired 了，就让他发了。同 Parker 教授一样，他也说：越是真正的有科学思想的文章，越容易被 rejected ；反而是一些平庸的文章容易发表。你们年轻人不要怕文章给人家 rejected ，要 keep trying ！ 把这句话转述给刚开始自己 career 的年轻人。 磁重联漫谈 （4）：Sweet-Parker模型 Giovanelli 的理论只是一个定性的、初步的想法。而要解决物理问题，需要定量的研究。最早试图定量研究磁重联的模型应该是 1957 年提出的 Sweet-Parker 模型。 这个模型应该被称为磁重联的“一维”模型：因为假设了在等离子体携带磁力线进入“扩散区”的方向（“入流”方向，通常选作为 x- 方向）上的特征尺度远远小于磁力线重联以后携带等离子体离开“扩散区”的方向（“出流”方向，通常选作为 y- 方向）的特征尺度。至于另外一个方向（ z- 方向），我们可以称之为“ transparent ”方向。也就是说，这个方向上的特征尺度更长，所以可以看成是“透明”的，即任何一个 z= 常数的横截面都应该是相同的——完全忽略了沿着这个方向的变化。 可能有人会问：忽略了 z- 方向上的变化，那应该是二维模型呀？不错，是二维的。但是因为“出流”方向（ y- 方向）的变化也是大尺度的，我们在实际的计算中只考虑了这个尺度特征尺度，而没有计入具体的空间变化形式。 这个模型的物理图像是这样的：如果在等离子体中存在一个沿着 z- 方向的“电流片”，那么电流的方向显然可以看成“ transparent ”方向。既然是“片”其宽度一定远远大于厚度。于是我们又可以简化其在宽度方向的变化。如果其厚度很薄，在流体近似下可以忽略，那我们就有了电流奇异性（ current singularity ），而这个奇异性正是 Sweet-Parker 模型的关键（不过，这一点人们在三十多年后才认识到）。 显然，电流片两侧的磁场是反向的。如果这些反向的磁力线因为外界的驱动或者磁场自身的自由能而相互“靠拢”（ merging ）。磁重联就发生了。 Sweet-Parker 模型假设电流片外的物理过程是“稳态”的（ steady state ）， dF/dt = 0 —— 这里和后面 d/dt, d/dx 都应该是偏导数，可惜没有相应的符号。那么磁通量的变化率（单位时间流入电流区的磁通）应该等于 v x dF/dx ，这里 v x 显然是等离子体“入流”的速度，这里的 F 是磁通。在模型的二维几何下，某一点的磁通定义为：从该点到原点连一条截线，通过这条截线的磁力线根数。根据这个定义，我们有： v x dF/dx = v x B y 。这在物理上很明显：就是单位时间在 x- 方向被带进电流片区的沿着 y- 方向的磁力线的根数！ 这就是S weet-Parker 模型的“外区解”（ outer region solution ），再简单不过！ 那么，电流片内呢？ 因为电流片很薄，两边的磁力线 merging ，所以电流片内 v x 趋近于零！磁通的变化只有 dF/dt 这一项。从磁感应方程， DF/Dt = dF/dt = h J = h B y / D 。这里 D/Dt 用来表示全导数， h 是电阻率， J 是电流密度， D 是电流片的半厚度。后面两个等号前面应该还有常数，为简单起见我们把它们无量纲化了。这个方程就是 Ohm 定律：电场等于电阻乘电流——因为磁通 F 显然就是磁场的矢势的 z 分量，其时间微分就是没有静电分量的电场（差一个光速因子），又是再简单不过！关键点在于把电流 J z = dB y /dx （无量纲化了前面的常数因子）简化成 B y / D 。这很明显：横跨电流片 D B y / D x=2B y /2 D 。 D 趋向零就等于 dB y /dx 。 另一个关键点是将“内区解”（ inner region solution ）的磁通变化率 DF/Dt = h B y / D 与“外区解”的磁通变化率 DF/Dt = v x B y 相“匹配”（ matching ），得到电流片的半宽度 D = h /v x 。 这是 Sweet-Parker 模型的神来之笔！就这么一个等号，可以写整整一厚本数学书，名字叫：《渐进方法》（ Asymptotic Methods ）。具体到这里，用的是“边界层”理论（ boundary layer theory ）。当然，这么“匹配”会有人不同意的。更严格的理论是在 60 年代中期发展的。而 Sweet-Parker 模型真正适用的非线性电阻磁重联理论里，严格的理论一直就没有发展！！（有志气的年轻人不妨做一做。 ）可是数值模拟和实验研究都证明了这个简单模型的正确！ Amazing ！ 再下面的就是简单的不可压缩性： v x L y = v y D 。这里 L y 就是电流片宽度方向的特征尺度， v y 则是“出流”的速度（物理上可以证明等于当地的 Alfven 速度）。带入 D = h /v x ，我们得到 Sweet-Parker 模型最重要的结论：磁重联的速率（磁力线进入电流片即“扩散区”的速率） v x ～ D ～ h 1/2 这个结果，虽然屡受挑战，但在电阻磁重联理论中“独领风骚”的地位至今难以动摇。 这再次告诉我们：只要抓住了关键，就可以用最简单的模型（这个模型仅仅是个一维模型——另一维的 info 仅仅是在不可压缩性里引入了一个尺度 L y ）得到最重要的结果。 我们常说：某个工作有“物理”。这就是“物理”！ 这个模型是 1957 年 Sweet 在一次会议上提出的几何模型和设想（会议文集 1958 年发表）；同年 Parker （就是提出“太阳风”理论的那位）在 JGR 上发表了第一篇有上述推导过程的论文。 当然，这个模型仅仅是一个“半定量”的“ scaling ”模型。“严格”的理论是后来才发展起来的。 磁重联漫谈（5）：Sweet-Parker模型（续） Sweet-Parker 模型看起来很完美，特别是其给出的 v x ～ D ～ h 1/2 的磁重联速率。 记得当 年在 UC Santa Barbara 的 ITP 做访问的时候，一位 Fields 奖得主来讲 Knot 理论，举了一个有意思的例子： 假设有 N 条平行的高速路，再在其上架设另一方向（与下面的路成一个角度）的 N 条平行的高速路。这样“上面”的交通和“下面”的交通相互独立。所以可以看成分属两个拓扑结构。如果上面任意一条路上的交通要到下面去，就要进行 N 个“操作”，即与下面的每条路都要交叉一次。我们把每个操作定义为一次“ crossing ”。那么整个拓扑的改变（上面的交通全部转到下面去）就需要 N 平方个“ crossing ”。 另外一个数学家站起来说：有一个办法可以减少“ crossing ”的数目！这些“高速路”构成一个有 N 平方个可能做“ crossing ”的点的网格。只要我们沿着其中的一列（或者行）做这样的操作：在每个交叉点上把要“交汇”的上下两条高速路“断开”，然后再把上面的右半条（或者平面顶部半条）与下面的右半条（或者平面顶部半条）“重新连接”起来；把上面的左半条（或者平面底部半条）与下面的左半条（或者平面底部半条）“重新连接”起来；则只需要N次操作，所有上面的交通都可以“下去”，所有下面的交通也都可以“上来”！ 物理学家们起来说：第一种情况是“扩散”：把上面的交通都“扩散”到下面去，下面的也“扩散”上来；而第二种情况是“重联”：不同拓扑结构通过“断开”和“重新连接”而联通起来！ 这是个典型的二维重联问题！ 有意思的是，我们知道磁扩散率是和电阻率 h 成正比的。根据上面的拓扑理论，这对应 N 2 ——而其“重联”率是 N ——正是“扩散”率的平方根！！ 这就是 Sweet-Parker 模型的结果：磁重联速率正比于 h 1/2 ！ 另外，可以看出：“扩散”可以随处发生，但是“重联”只发生在一个特殊的“列”或者“行”。物理上，这个选择不是任意的，而是在一定的拓扑结构“ separatrix ”上。（等离子体物理学界的同行们通常翻译成“分形线”（ 2D ）或者“分形面”（ 3D ）。） 磁重联漫谈（6）：简短几句 无碰撞磁重联应该最后谈，因为 很多重要问题没有解决。但是有读者问起，就简单说几句笔者个人的看法。 问题1 ： 您说过，电阻磁重联中电子和离子是从一根磁力线被 “ 碰撞 ” 到另一根磁力线。在 Hall 重联过程中，在扩散区电子离子运动分离，只有电子冻结在磁力线上。这样磁力线带着质量轻的电子会运动更快、重联更快，这应该是 Hall effect 加速磁场重联的物理图像吧。在这里我想问电子从一根磁力线跑到另一根磁力线的机理是什么？ Hall effect 并不是耗散项（磁通扩散项），在 Hall reconnection 中，若是没有电阻项重联还会发生吗？因为我看到别人做 Hall MHD reconnection 时，电阻项都被保留。 第一：是的，电阻磁重联是因为碰撞引起带电粒子从绕着一条磁力线转“变换”到围着另一条磁力线转； Hall 磁重联是因为离子的非磁化使得磁力线在 Hall 效应起作用的离子惯性区得以“甩掉包袱（离子）”，“轻装前进（只携带电子）”，或者说，磁力线的“惯性”突然变小，速度突然变快！ 第二：但是如问题所说，到底是什么机制“ break the field line ”，或者说使得电子从一条磁力线跳到另一条（所以我们不再能 clearly identify a field line ），还是一个 open question 。今天上午笔者在这里的 International Substorm Workshop 上 lead 磁重联 session 的讨论时，这正是 outstanding issues 之一。一个可能的 candidate 是波对电子的散射引起的所谓“反常电阻”效应，比如低混杂波（一种频率介于电子与离子回旋频率之间的静电波）对电子的散射。 问题2 ： 那么，在托卡马克中的 collisionless reconnection, 往往是电子惯性项被保留，而不是 Hall 项。这里想请王老师谈一谈电子惯性项加速磁场重联的物理图像是什么；在这里（有电子惯性项没有 Hall 项），离子的运动特征是什么？在 m=1 kink-tearing 和 m1 tearing, 电子运动特征的主要差异是什么 ？ 这里是好几个问题： 第一：托卡马克磁重联研究中， m=1 的 kink-tearing研究一般投影在磁场方向，所以 没有 Hall 电场项，但是有沿磁场方向的电子压强梯度项（而非电子惯性项）； 第二：对磁重联的加速体现在沿磁力线的电子压强梯度。但是，如果电子没有惯性，这一项会很快将电子加速到速度无穷大！这又是一个遇到奇点的时候必须把丢掉（忽略）的物理效应再捡起来的例子。注意：电子惯性反而是“减慢”的效应！ 第三：对于标量压强，其梯度是没有贡献的（因为在磁感应方程里 ,it is the curl of the term that really matters ）；所以只有压强张量的非对角项有贡献。而这些非对角项一般认为是 turbulent Reynolds stress ——我们再一次看到电子运动与湍流谱相互作用的贡献！这可能给我们指出一条最后明白这个问题的路。 至于 m1 tearing modes ，其本征函数是 localized ，与 m=1 kink 的 globalized 本征函数有根本的不同，所以本质上是慢时间尺度的电阻磁重联。 这些问题的具体物理图像，我们会慢慢讨论。 磁重联漫谈（7）：Petschek模型 Sweet-Parker 模型虽然很成功，但是存在一个致命的问题：磁重联的速率太慢。事实上，太阳大气等离子体的电阻率大约在 1/10 10-12 ，由此得到的重联率 v x ～ h 1/2 ～ 10 -5 -10 -6 Alfvén 速度，远远不能解释像日耀斑这样的快过程。 人们注意到 Sweet-Parker 模型重联率所以相对比较慢，原因是其重联区的拓扑结构近似是一维的，即我们前面说的：“等离子体携带磁力线进入‘扩散区’的方向（‘入流’方向，通常选作为 x- 方向）上的特征尺度远远小于磁力线重联以后携带等离子体离开‘扩散区’的方向（‘出流’方向，通常选作为 y- 方向）的特征尺度。”这样，由于“出口”太小、“进口”太大，导致已经“ merging ”到扩散区附近的磁力线的“排队等候”，物理学家用的词汇叫 magnetic flux “ piled up ”。（这样的过程会在重联区形成很薄的强电流片，其物理效应我们以后再谈。）因此，有人（ Petschek ， 1964 ）提出一种“快”磁重联模型：认为重联区的拓扑是呈具有 X 分形线的二维结构，这样入流区（在 y- 方向上的）长度与出流区（在 x- 方向上的）宽度大约在同一个数量级。而出流的“喇叭口”形状会形成一个如钱江潮的“慢激波”（道理相似，但相对运动方向相反）。根据这个“ slow shock ”（慢激波）上下游的连接条件，可以得到磁重联的速率 v x ～ - ln h h 1/2 h 这个几乎与电阻无关的重联率基本上可以很好解释日耀斑这样的快过程。 但是人们后来发现，在 Petschek 模型的物理讨论所依赖的电阻磁流体框架下，无法得到 X 型的磁场几何结构，除非电阻很大—— h 10 -3 （ W. Park, et al, 1984: Phys. Fluids 27 , 137; D. Biskamp, 1986: Phys. Fluids 29 , 1520; Z. W. Ma et al, 1995: Phys. Plasmas 2 , 8 ） 。而对于这么大的电阻， - ln h 与 h 1/2 的重联率几乎没有可以明显区分的差别！而在对应实际物理世界的电阻很小、 Sweet-Parker 和 Petschek 这两种模型的结果有可以明显区分的差别的情况下， 1980 年代以后发展的高精度的数值模拟结果告诉我们：即使初始条件取 Petschek 模型的磁场分布，我们也总是得到 Sweet-Parker 的电流片几何位形和 h 1/2 的重联率！ 后来人们才意识到：尽管 Petschek 模型的磁场拓扑结构是出于增大重联率的正确考虑，但是使用的电阻磁流体的物理模型是错误的！正确的快磁重联模型依赖于 1990 年代无碰撞磁重联理论的发展。 磁重联漫谈（8）：Tokamak的“有理”磁面 （一位朋友批评说：应该多写点托卡马克 ！写这么多磁重联，年轻人都去做磁重联了！ （写的时候没有想到这一点 :p 。无非是觉得自己对这个问题还有一些心得而已。这就做一点改正。其实等离子体物理的研究方向确实很宽。大家看了主要还是学习分析问题的出发点和方法。至于选择的具体方向，不妨根据自己的喜好、国家的需要、和单位的情况。） 笔者前面说到：“正确的快磁重联模型依赖于 1990 年代无碰撞磁重联理论的发展。”但实际上无碰撞磁重联理论早在 1966 年就与电阻磁重联的理论（而非模型）同时发展起来了。但是在介绍无碰撞磁重联的早期理论之前，我们先介绍电阻磁重联的理论发展。 前面说到的 Sweet-Parker 模型也好、 Petschek 模型也好，都还是半定量的模型，算不得定量的“理论”。电阻磁重联的线性理论最早是 1963 年由 Furth, Killeen, Rosenbluth 提出的（ Phys. Fluids 6, 459, 1963 ），被称为 FKR 理论。这个理论是针对在 Tokamak 位形下有理面上因为磁重联引发的“撕裂模”（ Tearing modes ），利用渐进方法中的边界层（ Boundary Layer ）理论，第一次得到电阻磁重联（撕裂模）的线性增长率。 笔者不打算在这里谈具体的数学计算，只是强调几个要点。 首先，介绍一下“有理面”： 磁约束等离子体的 Tokamak 环形装置看着像“轮胎”，或者“ Donut ”。里面的等离子体被约束在一层一层套着的“轮胎”（或者“ Donut ”）形状的“磁面”上——每个磁面都是一根磁力线绕成、并用一个物理量 q 来表征。显然 q 是随着“轮胎”小环半径 r 连续变化的—— q=q(r) 。这个物理量人们称之为“安全因子（ safety factor ），数值上等于磁力线绕大环的圈数和绕小环的圈数之比。 因为 q 是连续变化的，所以一定是由分立的有理数和这些有理数之间的连续的无理数组成。那么在那些具有有理数 m/n 的 q 值的磁面（我们称为“有理面”（ rational surface ））上，磁力线绕大环 m 圈同时正好绕小环 n 圈！所以有理面上的磁力线有下述性质： 1 ）首尾相接的闭合曲线， 2 ）只覆盖磁面上一个“测度”为零的部分。 这两个性质非常重要！ Tokamak 等离子体中千变万化的各种模式，大都是因为这两个性质或其中之一引起的。 我们先来看分立的有理面之间的那些连续分布的无理面（ irrational surface ）。很显然，因为这些面上 q 是无理数，所以磁力线不会在绕大环有限圈之时正好也绕小环有限圈，而只能这么无限地绕下去——铺满整个磁面。因为在等离子体中磁力线自身的“张力”，所以这些“无理”磁面非常“结实”。这就是为什么 Tokamak 整体约束还是不错的。但是那些磁力线“只覆盖磁面上一个测度为零的部分”有理面，特别是“低模数”（ m 、 n 很小）的、磁力线只绕那么一两圈的有理面，就显得格外“软”。而且更重要的：因为磁力线的周期性（首尾相接的有限长闭合曲线），则对于任何局域的扰动——沿着磁力线传播的都会传回来；垂直磁力线传播则总会有一个模数为（ m, n ）的本征模与这个有理面（ q=m/n ）上的磁力线的几何结构“共振”！从而引起各种不稳定性的增长。所以 Tokamak 上的有理面也称“共振面”（ resonant surface ）。 对于 Tokamak 中的磁重联过程来说，我们强调两点：第一，有理面是磁场的“拓扑分形面”（ topological separatrix ）；第二，有理面上的磁力线满足周期条件。这两点非常重要。后来的所谓“分量重联”理论忘掉了这两点（特别是最后一点），导致一些荒谬的结果。 磁重联漫谈（9）：有理面上的奇异性 前面说到： FKR 理论“是针对在 Tokamak 位形下有理面上因为磁重联引发的‘撕裂模’”。但是 Tokamak 的有理磁面都是轮胎形状的曲面。这样几何位形下的问题，处理起来是有一定难度的。 事实上，我们在研究等离子体的“宏观”尺度（一般指装置的特征尺度）约束时，理想磁流体理论是很好的近似。如我们在《磁重联漫谈（ 1 ）》中所说：“ 在等离子体的理想磁流体（ ideal magnetohydrodynamics, or ideal MHD ）近似下，等离子体与磁力线是‘冻结’（ frozen in ） 在一起运动。形象地说，就如我们小时候喜欢吃的‘棒冰’的冰冻结在中间的棍上一样。更准确的比喻是串在中间的杆儿上的算盘珠：可以很容易的沿着杆儿运动或者‘回旋’运动，但是没法‘跨越’这一根杆儿到另一杆儿上去。当然，如果等离子体中有不均匀性，还是会产生横越磁力线的‘漂移’（ drift ），但是如果磁场限制在有限的体积内，这种‘漂移’运动仍然限于同一磁力线所螺旋缠绕成的磁面上：不过是‘抄近路’到同一磁力线的另一部分而已。就像调皮的孩子在螺旋滑梯上直线地从‘一层’跳到‘另一层’。” 但是在这一近似下，等离子体磁通（ Magnetic Flux ，相当于磁矢势的主分量）的本征函数解在有理面上产生“奇异性”——其一阶导数（相当于磁场）产生阶跃；二阶导数（电流）产生 delta 函数奇异性。正如我们在前面（《物理学中的奇点》）讲到的： “数学物理方程的奇点表明，原来赖以得到这个方程（或者这组方程）的物理假设或者近似在这一点及其邻域不再成立，需要引进新的物理效应甚至新的物理模型。 。。。 “为了 resolve 这个‘奇点’，在物理上我们或者引进耗散效应（如粘滞或者电阻）、或者引进构成介质的微观粒子本身的‘分立’效应（如带电粒子的回旋半径这样的动理学（ kinetic ）效应）。” 如果我们在有理面附近非常薄的一个薄层里（在理想磁流体极限下这个薄层的厚度为零！）引进耗散（电阻）效应，导致电阻撕裂模理论（即 FKR 理论和 Rutherford 理论）；如果引进动理学（ kinetic ）效应，则给出无碰撞撕裂模理论。 正因为这个薄层非常薄，给我们处理问题反而带来极大的方便：第一，我们可以把轮胎形状的有理面沿着“赤道平面”切一刀，再沿任一环向角切一刀，展开成一个平面；第二，我们可以利用“边界层”理论来处理这一问题。 那么，有理磁面为什么会有这种奇异性？ 这是因为，连续变化的无理磁面的集合中嵌入一个具有分立性质有理磁面，相当于在连续变化的磁场结构中引入了拓扑不连续性。在理想磁流体图像中，磁场和等离子体是“冻结”在一起的，这种拓扑不连续性便转化成物理的不连续性（和更高阶导数的奇异性）。 这种理想磁流体图像中拓扑不连续性与物理不连续性的“不变性”，应该可以用一个数学定理或者物理量守恒定律描述。 磁重联漫谈（10）：有理面上的边界层 前面讲到有理面上的奇异性，提到：“正因为这个薄层非常薄，给我们处理问题反而带来极大的方便：第一，我们可以把轮胎形状的有理面沿着‘赤道平面’切一刀，再沿任一环向角切一刀，展开成一个平面；第二，我们可以利用‘边界层’理论来处理这一问题。”这两点是研究像磁重联这样在大尺度下存在“奇异性”的数学物理问题的关键。 其中“第一点”将复杂的三维问题变成了“一维”问题！ 把有理面展开成一个平面，则在两个延伸方向（大环和小环方向）上都有周期条件。做相应的 Fourier 展开之后，在每个特定的有理面上只有一个 Fourier 分量。且对应的微分符号变成代数符号。这样三维的微分方程在两个方向上“代数化”了，只剩下小环径向的变化。在物理上，这是由于有理面上的奇异性导致垂直有理面的特征尺度远远小于其它两个周期条件方向的尺度。 而“第二点”则为解决这样的问题提供了常用的方法。 我们知道，对连续介质中没有外部驱动时物理量 F 随时间演化的典型数学物理方程基本上都是带有耗散项的“抛物型”方程，比如 dF/dt = DF/Dt + vDF/Dx = l D 2 F/Dx 2 这里 D 表示偏微分。方程的右边是所谓耗散项， l 是耗散系数。如果 F 是磁通（磁矢势的某一分量），则这个方程就是欧姆定律：左边是“电场”（包括 v x B 部分）， l 是电阻， D 2 F/Dx 2 是电流。等等。如果耗散很弱，耗散系数 l 非常非常小，则我们可以做“理想情况下”的近似，令 l = 0 。物理上就是，如果系统的特征尺度是 L ，那么，对应耗散（ dissipation ）的特征时间显然就是 T D =L 2 / l 。 l 趋于 0 对应于物理量 F 被 dissipated 的时间趋于无穷大。所以近似有 dF/dt = 0 ，或者说， F 基本保持不变。 这样的近似在绝大多数区间是适用的。但是如果区间里存在着奇异性，问题就来了：这个奇异性存在于一个很小的区间，引进一个非常小的特征尺度 D 。则其对应的特征时间尺度 t D = D 2 / l 成为一个可以和系统特征运动时间 T 0 相比拟的有限值！相应的，在这个奇异面上，方程右边的耗散项就不能忽略。这时，理想近似下得到的所谓“奇异面”因为这个耗散效应的存在变成了“奇异层”。显然这个“奇异层”的厚度 D ～ （ l T 0 ） 1/2 （我们又看到了 Sweet-Parker 模型的 1/2 方关系）。 这样一类在 “奇异层”外部可以用“理想近似”求解，但是在其内部必须考虑耗散项的数学物理问题，我们称之为“边界层问题” （ Boundary Layer Problems ）。求解的方法称为“边界层方法”。 磁重联漫谈（11）：边界层方法 前些日子收到空间中心一位研究生的来信，谈到他们组织了一个讨论班，每周开一次讨论会。笔者的这几篇“磁重联漫谈”也是他们讨论的内容。 第一个感觉是：我们做学生那会儿的钻研科学的风气还是一直传承下来了。前些年听到过好多同事感慨，学校的科学讲座没有多少人听，有时还要通过学工部的人组织学生去、或者是把听讲座作为得学分的要求。听说这些学生自己组织起来学，很高兴——不仅为他们的钻研精神，更为中国科学事业的发展前景。所以他们的组织者提出让我去讲一讲，没二话就答应了。 昨晚去玉泉路。大概有二、三十位研一的学生吧。都是很认真、好学的。而且很聪明，物理的直觉很好。这个“漫谈”即使只为这些年轻人写，也值得！ 继续说磁重联。 上一次讲到处理有理面上奇异性的“边界层方法”。数学上这种方法属于“渐进方法”（ Asymptotic Methods ）的一种。具体作法是：将所研究的物理问题分成两个区来讨论，一个是我们原来所研究的、理想磁流体近似成立的、但是“抠去”了奇点的“外区”（ outer region ）；一个是理想磁流体解的奇点的“邻域”所形成的“内区”（ inner region ）。在外区仍然使用理想磁流体方程，得到原先的有奇点的理想磁流体近似解。但是因为“抠去”了奇点（“拓宽”为内区），所以在外区理想磁流体近似解是“解析”的。而在内区，或者引入耗散（电阻），或者引入动理学效应（带电粒子回旋、电子惯性、乃至湍流效应等），得到 resolved 奇点的“内区解”。 数学上这样比较严格的表述听起来很“绕”，但是物理图像很简单：大尺度下理想磁流体是很好的近似，但是在小尺度下物理量（比如磁场、电流）的显著变化使得这个近似不再成立，必须把原来忽略的物理机制“找回来”。 在数学上马上遇到一个问题：外区和内区之间的界面在哪里？使用何种“边界”条件来连接这两个区的解？这是“边界层理论”的关键所在。 因为内区和外区使用不同的方程：比如内区使用电阻磁流体方程组，外区使用理想磁流体方程组，所以两个区的解无法在“边界”上平滑地连接。所以，任何直接做这种连接的企图都会导致解的一阶微商在连接点的不连续及二阶微商的奇异性。也就是说：这样做其实就是把原来的奇点分成两个隔开一点的奇点而已！那么，如何解决这个问题呢？ 具体作法是：如果原来的奇点作为坐标（比如 x ）原点，我们可以将外区解与内区解“匹配”起来，即令外区解在 x à ±0 时的极限等于内区解在 x à ±∞ 时的极限相等，作为连接内外区的“边界条件”——数学上称为“匹配条件”（ Matching Condition ）。 这在严格的数学意义下显得有点匪夷所思。可能这也是“渐进方法”至今只是应用数学的一个分支，而不登数学的大雅之堂的原因之一吧。但是在物理上这很好理解：从大尺度的外区看过来，在趋近小尺度（ x à ±0 ）的时候，非理想磁流体的效应正是将要显现而没有显现；而从小尺度的内区看出去，在趋近大尺度（ x à ±∞ ）的时候，非理想磁流体的效应正是将要消失而没有最后消失。 这就是“边界层理论”的精要所在。 大家周末愉快！ 磁重联漫谈（12）：撕裂模的线性理论 前面介绍了“边界层方法”。这里我们利用这个方法来讨论 Tokamak 等离子体中的“撕裂模”。 “撕裂模”（ Tearing Modes ）这个名字，最初是用来形容这个不稳定模式发展起来以后“电流片”被“撕裂”（或者说，“丝化”）的现象。现在看来这个想法是“ Too nave, sometimes too simple ”。事实上，电流并没有如人们开始想像的那样聚集到磁岛的中心（ O- 点附近），而是分布在磁岛的“边缘”，也就是“磁分形线”附近。因为这些“磁分形线”在 X- 点交汇，所以 X- 点反而是电流最强的地方。当然“撕裂模”这个名字还是被沿用下来了，不过现在是表示“磁场拓扑结构”被“撕裂”。 在理想磁流体近似下我们已经得到了“外区”的磁场不连续、电流奇异性的解。由边界层理论知道，只要我们知道了“内区”的解的形式，再利用 matching 条件把内、外解“连接”起来，问题就解决了。 对 Tokamak 等离子体中的“撕裂模”（除了 m=1 的扭曲 - 撕裂模）来说，内区解满足所谓“常数磁通”（ Constant- y ）近似。即对于空间变化来说，磁通函数 y （相当于垂直磁重联过程所在平面的磁矢势分量）在“内区”近似地是一个常数，即仅随时间变化。这个空间分布的近似常数，表示在某一特定时刻有多少条磁力线被“重联”。“常数磁通”近似的物理实质是，相对于磁通函数来说，磁场在不连续处的跳变是有限的。 在“常数磁通”近似下得到电阻磁流体方程组的内区解，然后利用前面介绍的边界层理论方法与理想磁流体方程组的外区解“连接（ matching ）”， Furth ， Killeen ，与 Rosenbluth 第一次得到了托卡马克等离子体中电阻撕裂模的线性增长率（ Phys. Fluids 6, 459, 1963 ）。这个增长率的标度是电阻率的 3/5 次方，比 Sweet-Parker 的重联率（标度为电阻率的 1/2 方）要慢得多（考虑空间及实验室等离子体中电阻率一般是 10 -10 的数量级）。后来人们发现， Sweet-Parker 的重联率实际上是“非常数磁通”（ Non-constant- y ）电阻撕裂模在非线性阶段的时间尺度。 与电阻撕裂模线性理论发展的同时，无碰撞（零电阻）撕裂模线性理论也发展起来（ Laval, Pellat, and Vuillemin, 1966: in Plasma Physics and Controlled Nuclear Fusion Research 2 (IAEA), p259 ； Coppi, Laval, and Pellat, 1966: Phys. Rev. Lett. 16, 1207 ）。被称为 LPV 撕裂模理论。 我们知道，磁重联的物理本质是等离子体在重联区的“退磁化”。这种“退磁化”效应或者是碰撞引起的，或者是带电粒子的有限 Larmor 半径效应（ FLR ， Finite Larmor Radius ）引起的。前者适用电阻撕裂模理论；后者适用无碰撞撕裂模理论。对于前者，内区物理过程用电阻磁流体方程来描述；而对于后者，内区物理过程应该用带电粒子的动理学（ kinetic ）方程来描述。 因为电子的回旋半径远远小于离子的回旋半径，所以在电子回旋半径的尺度范围，离子早已“退磁化”了。 LPV 理论就是基于这样的图像，在内区只考虑电子的动力学，而只把离子作为中性背景。在此假设条件下，得到内区解；然后与外区的理想磁流体解连接，最后得到无碰撞撕裂模的线性增长率。这个增长率显然与电阻无关，而与电子回旋半径的 3/2 次方成正比。 磁重联漫谈（13）：撕裂模的线性理论（续） 上一篇提到，因为电子的回旋半径远远小于离子的回旋半径，所以在电子回旋半径的尺度范围，离子早已“退磁化”了。 LPV 理论基于这样的图像，在内区只考虑电子的动力学，而只把离子作为中性背景，得到无碰撞撕裂模的线性增长率与电子回旋半径的 3/2 次方成正比。 这一结果很快被 U Maryland 的李逸群（ Y C Lee ）教授和 J F Drake 博士推广到了强磁化的 Tokamak 等离子体中。他们首先利用简单的物理分析估算出线性无碰撞撕裂模的增长率，然后从由 Vlasov 方程来推导。“严格”的理论结果和物理的估计符合得很好。堪称如何“做物理”的一个范例。 但是， 90 年代托卡马克物理实验进展和更快速的计算机的高精度大规模数值模拟手段的发展，使得人们认识到 60 年代开始发展起来的那些以电子动力学为主的无碰撞 撕裂模的线性理论是不完全的。事实上，在理想磁流体过程主导的“外区”和电子动力学主导的“内区”之间，存在着一个“离子惯性区”。在这个区域内（宽度近似为“离子惯性尺度”），离子“退磁化”的结果，使得磁力线卸去了沉重的离子惯性而只携带着依然磁化的电子运动。因此，磁力线运动的“惯性”突然降低了 3 个数量级。导致在这个区域里磁力线（及磁化的电子）的突然“加速”。而“退磁化”的离子则继续减速——和电子运动互相“解耦”。这是典型的 Hall 效应。所以“离子惯性区”也被称为“ Hall 效应区”。这样，原来的“内外区”边界层理论必须分成三个区来求解： MHD 区（外区）， Hall 区（中间区），电子动力学区（内区）。 可是实际上相应的理论并没有发展起来。主要原因应该是由于 Hall 效应起重要作用的地球空间等离子体中， Harris 电流片的厚度（相当于“外区”宽度）常常薄到“离子惯性尺度”。所以渐进方法失效。而且对于空间等离子体过程来说，线性稳定性并不重要。由于数值手段的发展，人们现在基本上是采用数值模拟的方法来对这一问题开展研究。因此发展起来的研究领域，被称作 Hall MHD Reconnection（Hall磁流体磁重联） 。 这里的所谓“离子惯性尺度”是由光速与离子等离子体频率之比 c/ w pi 来定义的。相应于我们熟知的电子趋肤深度 c/ w pe ，这一尺度的物理意义并不直观。如果考虑离子的“退磁化”，对应的特征尺度应该是离子回旋半径 V i,the / W ci ——离子热速度与离子回旋频率之比；或者“离子声”回旋半径 c s / W ci ——离子声速与离子回旋频率之比。但是我们如果重写“离子惯性尺度”就发现： c/ w pi =V A / W ci ！即等离子体的 Alfvén 速度与离子回旋频率之比。因此“离子惯性尺度”具有“ Alfvén ”回旋半径的非常直观的物理意义！而且这个尺度有一个特殊的性质：与磁场强度无关！这就是为什么这个尺度适用于磁零点附近的区域。事实上，离子惯性尺度只与等离子体密度有关（其它参数如光速、基本电荷、圆周率等都是自然界的基本常数）。 磁重联漫谈（14）：“离子撕裂模”迷雾 说起无碰撞撕裂模的线性理论，有一段历史值得一提。 前面说到 无碰撞撕裂模线性理论，即 LPV 理论，在发表时主要针对在地球磁尾等离子体中的应用：将地磁尾磁场简化成东西方向流动的“越尾电流片”（ cross tail current ）南北两侧、地 - 日连线方向上的反向磁场。而磁重联则被看成是零磁面（ neutral plane ）附近“非磁化”效应引起的。但是实际上地磁尾是地磁“偶极场”在 night side 被太阳风拉伸的结果——也就是说，无论拉伸得多厉害，在所谓的“零磁面” neutral plane 上总是存在的一个垂直该面、南北方向的非零“ normal ”磁场分量。因此电子在 neutral plane 上仍然是被磁化的。而且由于在这种情况下磁力线变成一组抛物线型的曲线，磁扰动引起形变在 neutral plane 上表现为磁力线的疏密变化；而环绕磁力线的电子的密度也被压缩和拉伸。这时，磁场扰动能量被转换成压缩电子密度的能量，撕裂模被稳定。 这种磁场分布的稳定性的本质，是原来被 零磁面分隔成两个不同拓扑区域的 磁场结构，因 neutral plane 上的“ normal ”分量联系起来。因此，扰动磁场只是使得磁力线变得疏密相间，但不再引起磁场拓扑的变化。 可是这样简单的物理图像当时却没有人想到！ 70 年代对这样的磁场位形下的撕裂模稳定性的解释是：电子压缩效应（ Electron Compressibility ）。因此有人提出：虽然电子被磁化了，但是如果 normal 磁场分量足够小，离子仍然是非磁化的，有可能提供不稳定性的自由能。 于是就有人来看色散关系： 1/ g =1/G e +1/G i 。 这里 g 是撕裂模的增长率， G e 是电子的贡献，是 G i 离子的贡献；分别同各自的质量的平方根成正比。所以 G e G i ， 1/G e 1/G i 。近似有 1/ g =1/G e ， g =G e = g e 。 人们就把色散关系改写成： 1/ g =1/ g e +1/ g i 。 这样写不是不可以，只要记住 g e 和 g i 的物理意义，把它们看成代表不同粒子贡献的参数。可是有人就误解（或者说“偷换”）了这一概念：既然电子对不稳定性没有贡献了，就简单地把它的那一项拿掉。于是把电子磁化、离子“非磁化”条件下的色散关系写成： 1/ g =1/ g i ，则 g = g i 。 并把这一新的“不稳定模式”称为“离子撕裂模”。因为 g i 比 g e 至少大 40 多倍，所以“离子撕裂模”反而变成了更快增长的不稳定性！！ 尽管 1986 年， LPV 三人中的 Pellat 和另一位法国物理学家 Lembege 指出了 “ 离子撕裂模 ” 的错误 。但是没有打中要害。致使这一理论竟然统治了磁尾磁重联研究 20 年之久！到 90 年代初期甚至有所谓 “ideal tearing” 的理论出现。可见当时对磁重联的物理图像的理解上的混乱。 其实，问题的本质在于我们前面说过的：扰动磁场只是使得磁力线变得疏密相间（即激发沿 neutral plane 传播的磁声波），但不再引起磁场拓扑的变化。 陈省身先生说得好：几何物理是一家。对物理过程的拓扑直观，往往能够更清楚地看到其物理本质。对磁重联研究来说尤其如此。
http://news.sciencenet.cn//htmlpaper/201162517283230417688.shtm 记者6月24日从中国科技大学获悉，中美印科学家合作烹制了宇宙大爆炸“夸克汤”，从而在世界上首次确定从普通物质到夸克物质的相变温度。6月24日出版的《科学》杂志以“量子色动力学相图的标度”为题，发表这一研究成果。 据悉，中美印科学家联合研究确定了从强子物质（即普通物质）到夸克胶子等离子体的相变（即状态转变）温度约为175百万电子伏特，相当于2万亿摄氏度。中方研究人员罗晓峰介绍说，宇宙初生时，亿万物质是一锅由自由的夸克和胶子组成的浓稠的“汤”，俗称“夸克汤”，即夸克胶子等离子体。寻找夸克胶子等离子体存在的证据并研究其基本性质，对研究早期宇宙具有重要意义。 他说，在通常情况下，夸克和胶子被强相互作用力禁闭在强子中。通过对普通原子核“加热”，有可能使强子“融化”而形成夸克胶子等离子体。2000年以来，科学家们利用美国布鲁克海汶国家实验室中的相对论重离子对撞机（RHIC）进行实验研究，发现了一些夸克胶子等离子体形成的证据。但是从强子物质到夸克胶子等离子体的相变温度尚不清楚。 日前，RHIC对撞机将两束金原子核加速到接近光速，使其发生碰撞，形成高能量密度和高温的夸克胶子等离子体，冷却后产生大量粒子。中美印科学家组成合作小组，研究分析对撞机上STAR探测器采集到的大量实验数据，在世界上首次把测量到的净质子数分布的特征，与格点量子色动力学的计算结果进行比较，从实验上直接确定了重子数密度为零的情况下从强子物质到夸克胶子等离子体的相变温度。（来源：中国新闻网 吴兰） Scale for the Phase Diagram of Quantum Chromodynamics Sourendu Gupta 1 , Xiaofeng Luo 2 , 3 , Bedangadas Mohanty 4 , * , Hans Georg Ritter 3 , Nu Xu 5 , 3 - Author Affiliations 1 Department of Theoretical Physics, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India. 2 Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China. 3 Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. 4 Experimental High Energy Physics and Applications Group, Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064, India. 5 College of Physical Science and Technology, Central China Normal University, Wuhan 430079, China. Matter described by quantum chromodynamics (QCD), the theory of strong interactions, may undergo phase transitions when its temperature and the chemical potentials are varied. QCD at finite temperature is studied in the laboratory by colliding heavy ions at varying beam energies. We present a test of QCD in the nonperturbative domain through a comparison of thermodynamic fluctuations predicted in lattice computations with the experimental data of baryon number distributions in high-energy heavy ion collisions. This study provides evidence for thermalization in these collisions and allows us to find the crossover temperature between normal nuclear matter and a deconfined phase called the quark gluon plasma. This value allows us to set a scale for the phase diagram of QCD.
General Public P. I. John, Plasma Sciences and the Creation of Wealth , Tata-McGraw-Hill, New Delhi, 2005. Yaffa Shalom Eliezer, The Fourth State of Matter , Hilger, Bristol, 1989 (2nd edition, 2001). John W. Freeman, Storms in Space, Cambridge, 2001. Kenneth R. Lang, The Cambridge Encyclopedia of the Sun, Cambridge Press, 2001. Hans Wilhelmsson, Fusion: A Voyage Through the Plasma Universe , IOP, 1999. Steven T. Suess and Bruce T. Tsurutani, From the Sun: Auroras, Magnetic Storms, Solar Flares, Cosmic Rays, American Geophysical Union, 1998. T. Kenneth Fowler, The Fusion Quest , Johns Hopkins Press, 1997. Kenneth R. Lang, Sun, Earth and Sky , Springer-Verlag, Berlin, 1995, 1997. Gareth Wynn-Williams, The Fullness of Space , Cambridge, 1992. Paul D. Thompson, Gases Plasmas, Lippincott Company, Philadelphia, 1966 (out of print) Introductory Plasma Science: Basic Physics of the Local Cosmos , National Academy Press, Washington D.C., 2004. A. A. Harms et al., Principles of Fusion Energy, World Scientific, 2000. R. Hazeltine and F. Waelbroeck, The Framework of Plasma Physics , Perseus Books, 1998. Plasma Science: From Fundamental Research to Technological Applications , National Academy Press, Washington D.C., 1995. R. J. Goldston and P. H. Rutherford, Introduction to Plasma Physics , IOP, 1995. Richard Dendy, Plasma Physics , Cambridge, 1993, 1995. Francis Chen, Introduction to Plasma Physics and Controlled Fusion , Plenum Press, 1974, 1988. Basic Plasma Physics Nonequilibrium Phenomena in Plasmas, A. Surjalal Sharma and Predhiman Kaw, eds., Springer, 2005. Takashi Fujimoto, Plasma Spectroscopy, Clarendon Press, Oxford, 2004. J. Goedbloed and S. Poedts, Principles of Magnetohydrodynamics: With Applications to Laboratory and Astrophysical Plasmas, Cambridge, 2004. T. Tajima, Computational Plasma Physics with Applications to Fusion and Astrophysics, Westview Press, 2004. William Kruer, The Physics of Laser Plasma Interactions, Westview Press, 2003. Y. Elskens and D. Escande, Microscopic Dynamics of Plasmas and Chaos, IOP, 2002. Per Helander and Dieter J. Sigmar, Collisional Transport in Magnetized Plasmas, Cambridge, 2002. Paul Gibbon, Short Pulse Laser Interactions with Matter , Imperial College Press, 2000. R. Davidson, The Physics of Nonneutral Plasmas , Imperial College Press, 2001. V. A. Rozhansky and L. D. Tsendin, Transport Phenomena in Partially Ionized Plasma, Taylor Francis Group, London, 2001. H. Wilhelmsson and E. Lazzaro, Reaction-Diffusion in the Physics of Hot Plasmas, IOP, 2000. J. T. Mendonca, Theory of Photon Acceleration, IOP, 2000. Paul Gibbon, Short Pulse Laser Interactions with Matter , Imperial College Press, 2000. J. Weiland, Collective Modes in Inhomogeneous Plasmas, IOP, 1999. S. S. Moiseev, V. Oraevsky, and V. Pungin, Non-Linear Instabilities in Plasmas and Hydrodynamics , IOP Press, 1999. Vladimir Fortov and Igor Iakubov, The Physics of Non-Ideal Plasma , Imperial College Press, 1999. Plasma Chemistry , L. S. Polak and Yu A. Lebedev, eds., Cambridge, 1999. V. V. Antsiferov and G. I. Smirnov, Coherent Radiation Processes in Plasmas , Cambridge, 1999. M. Brambilla, Kinetic Theory of Plasma Waves: Homogeneous Plasmas , Oxford, 1998. Hans R.Griem, Principles of Plasma Spectroscopy ,Cambridge, 1997. W. Horton and Y-H Ichikawa, Chaos and Structures in Nonlinear Plasmas , World Scientific, 1996. The Physics of Dusty Plasmas , P. Shukla, D. Mendis V. Chow, editors, World Scientific, 1996. Toshiro Ohnuma, Radiation Phenomena in Plasmas , World Scientific, 1996. C. S. Liu and V. K. Tripathi, Interaction of Electromagnetic Waves with Electron Beams and Plasmas , World Scientific, 1995 E. A. Oks, Plasma Spectroscopy , Springer-Verlag, 1995. W. Lochte-Holtgreven, Plasma Diagnostics , North-Holland, 1968, APS 1995. Dusty and Dirty Plasmas, Noise, and Chaos in Space and in the Laboratory , H. Kikuchi, editor, Plenum Press, NY, 1995. Sanborn C. Brown, Basic data of plasma physics , AIP Press, 1994. V. Shevelko and L. Vainshtein, Atomic Physics for Hot Plasmas , Oxford, 1993. Setsuo Ichimaru, Statistical Plasma Physics , Vol. 1. Basic Principles, Vol. 2. Condensed Plasmas, Perseus Books, 1992, 1994. Thomas Stix, Waves in Plasmas , AIP Press, 1992. Nonlinear and Relativistic Effects in Plasmas , V. Stefan, ed., AIP, 1992. A. Mikhailovskii, Electromagnetic Instabililties in an Inhomogeneous Plasma , IOP, 1992. R. A. Cairns, Radiofrequency Heating of Plasmas , IOP, 1991. Ronald Davidson, An Introduction to the Physics of Nonneutral Plasma , Addison-Wesley, 1990. W. Manheimer and C. Lashmore-Davies, MHD and Microinstabilities in Confined Plasmas , IOP, 1989. R. C. Cross, An Introduction to Alfven Waves , Hilger, Bristol, 1988. A. Galeev and R. Sudan, Basic Plasma Physics , North-Holland, 1989 (selections from Handbook of Plasma Physics , Vol. 1 2, 1983, 1984) J. P. Freidberg, Ideal Magnetohydrodynamics , Plenum Pr., NY, 1987. Plasma Waves and Instabilities , C. L. Grabbe, ed., American Assoc. of Physics Teachers, 1986. Dwight Nicholson, Introduction to Plasma Theory , Wiley, 1983. E. Lifshitz and L. Pitaevskii, Physical Kinetics: Volume 10 , Elsevier, 1981. N. Krall and A. Trivelpiece, Principles of Plasma Physics , McGraw-Hill, 1973. Fusion Plasmas Jeffrey Freidberg, Plasma Physics and Fusion Energy, Cambridge Univ. Press, 2007. Plasma Physics: Confinement, Transport and Collective Effects, A. Dinklage et al., eds., Springer-Verlag, 2005. G. McCracken and P. Stott, Fusion: The Energy of the Universe, Elsevier, 2005. J. Wesson, Tokomaks, 3rd ed. , Oxford Univ. Press, 2004. C. Braams and P. Stott, Nuclear Fusion: Half a Century of Magnetic Confinement Fusion, IOP Press, 2002. R. Davidson and H. Qin, Physics of Intense Charged Particle Beams in High Energy Accelerators, Imperial College Press, 2001. P. C. Stangeby, The Plasma Boundary of Magnetic Fusion Devices , IOP Press, 2000. Paul M. Bellan, Spheromaks , Imperial College Press, 2000. M. Liberman, J. Degroot, A. Toor, and L. Spielman, Physics of High-Density Z-Pinch Plasmas , Springer, 1999. M. Wakatani, Stellerator and Heliotron Devices , Oxford Univ. Press, 1998. J. Lindl, Inertial Confinement Fusion , Springer, 1998. A. B. Mikahilovskii, Instabilities in a Confined Plasma , IOP, 1998. Laser Plasma Interactions 5: Inertial Confinement Fusion , M. Hooper, ed., IOP, 1996. Physics of High Energy Particles in Toroidal Systems , T. Tajima and M. Okamoto, eds., AIP Press, 1994. M. N. Rosenbluth, New Ideas in Tokamak Confinement , Springer, 1994. B. Kadomtsev and I. Kurchatov, Tokamak Plasma: A Complex Physics System , IOP, 1993. M. Nezlin and I. Kurchatov, Physics of Intense Beams in Plasmas , IOP, 1993. H. L. Berk, Fusion, Magnetic Confinement , in Encyclopedia of Applied Physics, Vol. 6, pp. 575-607, VCH Publishers, Inc., 1993. Richard D. Hazeltine and James D. Meiss, Plasma Confinement , Perseus Books, 1992. High-frequency Plasma Heating , ed. A. Litvak, AIP, 1992. K. Nishikawa, and M. Wakatani, Plasma Physics: Basic Theory with Fusion Applications , Springer-Verlag, 1990. Kenro Miyamoto, Plasma Physics for Nuclear Fusion , MIT Press, 1980, 1989. J. Reece Roth, Introduction to Fusion Energy , Lincoln Rembrandt, Charlottesville, 1986. Weston Stacey, Fusion: An Introduction to the Physics and Techniques of Magnetic Confinement Fusion , Wiley, 1984. Space Plasmas The Mars Plasma Environment, C. T. Russell, ed., Springer, 2007. Cosmic Magnetic Fields, R. Wielebinski and R. Beck, eds., Springer-Verlag, 2005. Wolfgang Kundt, Astrophysics: A New Approach, Springer-Verlag, 2005. D. A. Gurnett and A. Bhattacharjee, Introduction to Plasma Physics with Space and Laboratory Applications, Cambridge, 2005. James Lequeux, The Interstellar Medium, Springer-Verlag, 2005. A. C. Das, Space Plasma Physics: An Introduction, Narosa Publishing House, New Delhi, 2004. Gunther Rudiger and Rainer Hollerbach, The Magnetic Universe: Geophysical and Astrophysical Dynamo Theory , Wiley-VCH, 2004. Gerd W. Prolss, Physics of the Earth's Space Environment, Springer-Verlag, 2004. Solar and Space Weather Radiophysics, Astrophysics and Space Science Library, Vol. 314, Dale Gary and C. Keller, eds., Kluwer, 2004. J. Goedbloed and S. Poedts, Principles of Magnetohydrodynamics: With Applications to Laboratory and Astrophysical Plasmas, Cambridge, 2004. M-B Kallenrode, Space Physics: An Intro to Plasmas and Particles in the Heliosphere and Magnetospheres , Springer-Verlag, 2001, 2004. Toshi Tajima, Computational Plasma Physics: With Applications to Fusion Astrophysics, Perseus, 2004. Markus Aschwanden, Physics of the Solar Corona, Springer-Verlag, 2004. Exploration of the Outer Heliosphere and the Local Interstellar Medium, NAS/NRC, National Academies Press, Washington, DC, 2004. Space Plasma Simulation, Jorg Buchner et al., eds.,Springer-Verlag, 2003 Alan C. Tribble, The Space Environment: Implications for Spacecraft Design, Princeton, 2003. Arnoldo O. Benz, Plasma Astrophysics: Kinetic Processes in Solar and Stellar Coronae, Kluwer Academic Publ., 2002. Syun-Ichi Akasofu, Exploring the Secrets of the Aurora, Kluwer Academic Publ., 2002. Arnold Hanslmeier, The Sun and Space Weather, Kluwer Academic Publ., 2002. H. Kikuchi, Electrodynamics in Dusty and Dirty Plasmas - Gravito-Electrodynamics and EHD , Kluwer, 2001. Space Weather, Paul Song, Howard J. Singer, and George L. Siscoe, eds., Geophys. Mono. 125, American Geophysical Union, 2001. Plasma Astrophysics, B. Coppi et al, eds.Vol. 142, Int'l School of Physics Enrico Fermi, 2000. E. Priest and T. Forbes, Magnetic Reconnection: MHD Theory and Applications, Cambridge, 2000. F. Verheest, Waves in Dusty Space Plasmas, Kluwer, 2000. A. Choudhuri, The Physics of Fluids and Plasmas: An Intro for Astrophysicists , Cambridge, 1999. Jorg Buchner, Plasma Astrophysics and Space Physics, Kluwer Academic Publ., 1999. Vinod Krishan, Astrophysical Plasmas and Fluids , Kluwer Academic Publ., 1999. Magnetic Helicity in Space and Laboratory Plasmas, M. R. Brown, R. C. Canfield, A. A. Pevtsov, eds., Geophys. Mono. 111, American Geophysical Union, 1999. Sun-Earth Plasma Connections, J. L. Burch, R. Carovillano, S. Antiochos, ed., Geophys. Mono. 109, American Geophysical Union, 1999. Measurement Techniques in Space Plasmas, Particles, ...Fields, R. F. Pfaff, J. Borovsky, D. Young, eds., Geophys. Mono. volumes 102, 103, American Geophysical Union, 1998. D. Bryant, Electron Acceleration in the Aurora and Beyond , IOP, 1998. M.-B. Kallenrode, Space Physics: Plasmas and particles in the Heliosphere and Magnetosheres , Springer, 1998. T. Tajima and K. Shibata, Plasma Astrophysics , Addison-Wesley, 1997. R. A. Treumann and W. Baumjohann, Advanced Space Plasma Physics , World Scientific, 1997. J. F. Lemaire, D. Heynderickx, and D. N. Baker, eds., Radiation Belts: Models and Standards, Geophys. Mono. 97, American Geophysical Union, 1996. W. Baumjohann and R. A. Treumann, Basic Space Plasma Physics , World Scientific, 1996. V. V. Zheleznyakov, Radiation in Astrophysical Plasmas , Kluwer Academic Publ., Dordrecht, 1996. The Physics of Dusty Plasmas , P. Shukla, D. Mendis and V. Chow, eds., World Scientific, 1996. Plasma Astrophysics and Cosmology , Anthony L. Peratt, ed., Kluwer, 1995. Margaret Kivelson and Chris Russell, Introduction to Space Physics , Cambridge, 1995. J. Buchner, Physics of Space Plasmas, MIT Press, 1995. Charles F. Kennel, Convection and Substorms , Oxford Univ. Press, 1995. Leonard F. Burlaga, Interplanetary Magnetohydrodynamics , Oxford Press, 1995. P. Sturrock, Plasma Physics: An Intro to the Theory of Astrophysical, Geophysical, and Laboratory Plasmas , Cambridge, 2004. J. G. Kirk, D. B. Melrose, and E. R. Priest, Plasma Astrophysics , Springer-Verlag, 1994. Sergei Sazhin, Whistler-mode Waves in a Hot Plasma , Cambridge Univ. Press, 1993. S. Peter Gary, Theory of Space Plasma Microinstabilities , Cambridge, 1993. Anthony Peratt, Physics of the Plasma Universe , Springer-Verlag, 1992. George Parks, Physics of Space Plasmas , Addison-Wesley, 1991. Modeling Magnetospheric Plasma Processes , G. Wilson, ed., American Geophysical Union, 1991. F. Curtis Michel, Theory of Neutron Star Magnetospheres , U. Chicago, 1991. Numerical Simulation of Space Plasmas , B. Lembege and J. Eastwood, eds., North-Holland, 1988. Donald Melrose, Instabilities in Space and Laboratory Plasmas , Cambridge, 1986. Eric Priest, Solar Magnetohydrodynamics , Reidel, 1985. Plasma Technology Plasma Technology for Textiles, R. Shishoo, ed., Woodhead Publ., Cambridge, 2007. The Physics and Technology of Ion Sources, Ian Brown, ed., Wiley, 2004. A. Fridman and L. Kennedy, Plasma Physics and Engineering, Taylor and Francis, 2004. Emerging Applications of Vacuum-ARC-Produced Plasma, Ion, and Electron Beams, E. Oks and I. Brown, eds, Kluwer, 2003. Bundesministerium fur Bildung und Forschung, Plasma Technology, BMBF (www.bmbf.de), Germany, 2001 (in German and English - www.bmbf.de/pub/plasma_technology.pdf) J. Reece Roth, Industrial Plasma Engineering, Vol. 2 - Applications, IOP, 2001. E. Bazelyan and Y. Raizer, Lightning Physics and Lightning Protection, IOP, 2000. K. Muraoka and M. Maeda, Laser Aided Diagnostics of Gases and Plasmas, IOP, 2000. Yu. M. Aliev, H. Schluter, and A. Shivarova, Guided-Wave-Produced Plasmas, Springer, 2000. W. N. G. Hitchon, Plasma Processes for Semiconductor Fabrication, Cambridge, 1999. Dusty Plasmas: Physics, Chemistry and Technological Impacts in Plasma Processing, Andre Bouchoule, ed., Zukov and O. Solonenko, eds., Lavoisier, 1999. Thermal Plasmas and New Materials Technology , vol 12, M. Zukov and O. Solonenko, eds., Cambridge, 1999. H. Zhang, Ion Sources, AIP, 1999. M. Sugawara, Plasma Etching: Fundamentals and Applications, Oxford, 1998. Microlithography: Science and Technology , J. R. Sheats and B. W. Smith, eds., Marcel Dekker, NY, 1998. I. C. E. Turcu and J. B. Dance, X-Rays from Laser Plasmas , Wiley, 1998. Generation and Application of High Power Microwaves , R. Cairns and A. Phelps, eds., IOP, 1997. Environmental Aspects in Plasma Science , Sugiyama, L., T. Stix, and W. Mannheimer, eds., AIP Press, 1997. Y. P. Raizer and J. E. Allen, Gas Discharge Physics, AIP, 1997. Plasma Science and the Environment , W. Manheimer, L. Sugiyama, and T. Stix, eds., AIP, 1996. R. Geller, Electron Cyclotron Resonance Ion Sources and ECR Plasmas , IOP, 1996. Dynamics of Transport in Plasmas and Charged Beams , G. Maino and M. Ottaviani, eds., World Scientific, 1996. 12th International Symposium on Plasma Chemistry , J. V. Heberlein, D. W. Ernie, and J. T. Roberts, Int'l Union of Pure and Applied Chemistry, Univ. of Minnesota Pr., Minneapolis, Aug., 1995. Rimini, E., Ion Implantation: Basics to Device Fabrication , Kluwer Academic Publishing, Boston,1995. Stephen O. Dean and N. Poltoratskaya, " Applications of Fusion and Plasma Device Technologies ," in Plasma Devices and Operations, Vol. 4, 1995. J. Reece Roth, Industrial Plasma Engineering, Vol. 1 - Principles, IOP, 1995. Michael Lieberman and Allan Lichtenberg, Principles of Plasma Discharges and Materials Processing , Wiley Sons, 1994. Alfred Grill, Cold Plasma in Materials Fabrication , IEEE Press, 1994. J. C. Miller, Laser Ablation , Springer-Verlag,1994. Plasma Spraying: Theory and Applications , ed. R. Suryanarayanan, World Scientific, 1993. Non-thermal Plasma Techniques for Pollution Control , B. M. Penetrante and S. E. Schulteis, eds., NATO-ASI Series G, Vol. 34, Parts A and B, 1993. Plasma Technology: Fundamentals and Applications , eds. M. Capitelli and C. Gorse, Plenum Press, 1992. Dry Etching for VLSI , eds. A. J. van Roosmalen, J. A. G. Baggerman, S.J.H. Brader, Plenum Press, NY, 1991. Handbook of Plasma Processing Technology , eds. S. Rossnagel, J. Cuomo, and W. Westwood, Noyes Publications, 1990. Plasma Polymerization and Plasma Interactions with Polymeric Materials , ed. H. Yasuda, Wiley Sons, 1990. Plasma Diagnostics , eds. O. Auciello and D. Flamm, Academic Press, 1989. Plasma Etching , eds. D. Manos and D. Flamm, Academic Press, 1989. A. Chambers, R. Fitch, Walmley, S. Coldfield, and B. Halliday, Basic Vacuum Technology , IOP Publ., 1989. Russ Morgan, Plasma Etching in Semiconductor Fabrication , Elsevier, 1985. Plasma Diagnostic Techniques , eds. R. Hudlestone and S. Leonard, Academic Press, 1978. Techniques and Applications of Plasma Chemistry , eds. J. Hollahan and A. Bell, Wiley Sons, 1974. Computational Plasma Physics T. Tajima, Computational Plasma Physics: With Applications to Fusion and Astrophysics , Addison Wesley, 1989. C. K. Birdsall, and A. B. Langdon, Plasma Physics via Computer Simulation , McGraw-Hill, 1985, 1991. Hockney and Eastwood, Computer Simulation using Particles , Adam Hilger, 1988. _______________________________________________________ New and Special Sources Plasma science materials from Russia and other FSU states are a specialty of Cambridge International Science Publishing . William Beaty's Nikola Tesla and Tesla Coil page and resources on ball lightning Vladimir Rokov and Martin Uman, Lightning Physics and Effects, Cambridge Press, 2003. http://www.plasmas.org/references.htm
Dear Colleagues, The International Scientific Committee and the Local Organizing Committee are pleased to invite you to participate in the XXX International Conference on Phenomena in Ionized Gases (ICPIG), which will be held in Belfast, Northern Ireland, on August 28th September 2nd 2011 . The XXX ICPIG will cover a wide range of fundamental and applied aspects of ionized gases. This conference emphasises interdisciplinary research and fosters exchange between different communities. All interested participants are kindly invited to present the latest results of their scientific work in one of the ICPIG subject areas. The first announcement is attached and more details can be found on the regularly updated website: http://www.qub.ac.uk/sites/icpig2011/ We wish you enjoyable Christmas holidays and a happy new year, Timo Gans on behalf of the LOC. ----------------------------------------------------------------------------------- 30. International Conference on Phenomena in Ionized Gases ICPIG Belfast 2011 Queen's University Belfast, Northern Ireland, UK 28. August - 2. September 2011 http://www.qub.ac.uk/icpig2011 icpig2011@qub.ac.uk Local Organising Committee Chair: Timo Gans Queen's University Belfast, Northern Ireland, UK International Scientific Committee Chair: Ursel Fantz Max-Planck-Institut fuer Plasmaphysik, Garching, Germany Secretary: Nicholas Braithwaite The Open University, Milton Keynes, UK Topics A. Fundamentals 1) Elementary processes and fundamental data Reaction paths, plasma chemistry, cross sections, swarm studies and data 2) Thermodynamics and transport phenomena Distribution functions, kinetic theory, transport models, dissipation, heating mechanisms 3) Plasma wall interactions, electrode and surface effects Secondary emission, wall erosion, surface reactions, edge plasmas in fusion devices 4) Collective and Nonlinear Phenomena Boundary sheaths, flows, waves, shocks, instabilities, self-organization, chaos, plasma-beam interaction, magnetized plasmas. B. Modelling, Simulation, and Diagnostics 5) Modeling and simulation techniques Analytical techniques, numerical methods, codes, visualization tools 6) Plasma diagnostic methods Optical, electrical, particle and laser-assisted diagnostics. Other plasma diagnostics methods C. Plasma Sources and Discharge Regimes 7) Astrophysical, geophysical and other natural plasmas Cosmic plasmas, interstellar nebula, magnetospheres, ionospheres, lightning, sprites 8) Low pressure plasmas DC glows, magnetrons, pseudo-sparks, edge-physics of fusion devices 9) High frequency discharges Radio-frequency and microwave driven discharges 10) Non-equilibrium plasmas and microplasmas at high pressures Breakdown, streamers, sparks, coronas, surface discharges, dielectric barrier discharges, high pressure glows, microplasmas 11) Thermal plasmas Arcs, thermo-ionic arcs, thermal plasma torches 12) Complex and dusty plasmas, ion-ion plasmas Particle dynamics, plasma crystals, structure formation, negative ion dominated plasmas D. Applications 13) Plasma processing of surfaces and particles Plasma etching and deposition, surface activation, thin film technology, generation, coating and deposition of nano-particles 14) High pressure and thermal plasma processing Torches, plasma synthesis, combustion, plasma spraying, pollution control 15) Plasma lamps and radiation sources Low and high pressure lamps, flat-panel plasma displays, X-ray sources, medical imaging, resistive plate detectors, gaseous photomultipliers. 16) Medical, biological, environmental and aeronautical applications Plasma sterilization, bio compatible coatings, diffusion barriers, plasma actuators and igniters 17) Plasma power and pulsed power technology, particle sources MHD and other plasma generators, circuit breakers, plasma switches, high power electron beams, Hall thrusters, Z Pinch, Theta pinch, and Plasma Focus apparatus
The 10th APCPST (Asia Pacific Conference on Plasma Science and Technology) and 23th SPSM (Symposium on Plasma Science for Materials) will be jointly held for July 4 - 8, 2010 at Jeju island in Korea . The conference details can be found in the attached 1 st circular or on the web homepage ( http://www.apcpst2010.org ). Important deadline: Abstract submission by March 28, 2010 The submitted regular manuscripts will be published in a SCI-rated journal, Thin Solid Films (Elsevier Science) as a special issue after peer review Topics 1. Basic plasma physics generation - Atmospheric/thermal/low-temperature plasma - Plasma sources, simulation and modeling, plasma diagnostics, plasma sources - Plasma chemistry, plasma-surface interactions 2. Material synthesis etching by plasma - Surface modification etching by plasma - Synthesis of thin films nano-structured materials - Large-scale plasma processing 3. Various applications of plasmas - Plasma process for semiconductor, display, and energy conversion devices - Plasma process for transparent, flexible, or stretchable electronic devices - Plasma for fusion energy - Plasma for bio medical application - Other applications We hope you could join the conference as we feel your participation will provide a strong contribution to the program. Yours Sincerely, Chi Kyu Choi, Conference Chair
It is our great pleasure to inform you that the 15th International Congress on Plasma Physics (ICPP 2010) will be held in Santiago, capital of Chile, during August 8-13, 2010, in combination with the 13th Latin American Workshop on Plasma Physics (LAWPP 2010). We invited all of you to be part of this great scientific event. For more information, visit www.icpp-lawpp-2010.cl Leopoldo Soto (chairman) and Local Organizing Committee Topics Fundamentals of Plasma Physics Fusion Plasmas Plasmas in Astrophysics and Space Physics Plasma Applications and Technologies Complex Plasmas High Energy Density Plasmas Quantum Plasmas Laser-Plasma Interaction ITER Project NIF Project Schedule： Early registration March 15th June 15th Abstract submission March 15th April 3th Desk registration (School) August 1st (Sunday) School on Plasma Physics August 2nd August 6th Desk registration (ICPP-LAWPP-2010) August 8th (Sunday) ICPP LAWPP 2010 August 9th August 13th
解读等离子体天线 刘红 魏佳羽 近日科学网上发布了一则关于等离子天线的报道 （ http://www.sciencenet.cn/htmlnews/2007112281030111194869.html?id=194869 ），此消息来源于美国物理学会等离子体物理分会的年会 : http://meetings.aps.org/Meeting/DPP07/Event/69787 上的报告 , 《 Plasma Antenna Shielding 》 . A method and calculation have been developed to protect space based antennas using plasma Frequency selective surfaces radom. The antennas we are trying to protect are currently metal but could be plasma. The scattering process of the electromagnetic waves has been investigated in a plasma antenna tube; this process is of self-important value from the point of view of studying wave propagation and absorption. When electromagnetic waves propagate in media with random inhomogeneities, there appear waves with frequencies and wave vectors which are different from the frequency and wave vector of the fundamental wave. Here, the so-called scattering process occurs. If the medium is spatially homogeneous but parameters defining its electromagnetic properties experience fluctuations, then scattering must occur on these fluctuations, the latter being random inhomogeneities. Induced charges and currents leading to radiating new scattered waves emerge in a medium under the influence of the fundamental wave, thereby initiating the appearance of scattered waves. However, within the linear approximation induced charges and currents in the homogeneous medium represent only the modification of wave propagation characteristics in a medium, as compared to vacuum, i.e., modification of the complex refractive index. The results may be generalized for physical understanding of the scattering process in plasma. 文中提到这种新型天线非常适合军事用途，并且将在移动电话网络中大显身手。同时比较金属天线的一些“缺点”：低频天线体积很大；高频天线虽然体积很小，但其在发射高频信号时却很容易暴露它们的位置；金属天线容易受到干扰和抑制，指出这种新型天线巧妙的克服了这些问题。我们将结合等离子体的性质针对上述特点给出一些解释 , 既然谈到等离子体，那么总要先说清楚究竟什么是等离子体？众所周知我们身边的物质绝大多数处于固态，液态，气态这三种状态，但无论是固体，液体还是气体它们都是由中性的原子组成 , 而原子又可以进一步分解为原子核和核外电子，核外电子在通常情况下会被束缚在原子核周围 , 但是如果核外电子获得了较高的能量，它们将会逃离原子核的束缚，（我们称该过程为电离），从而成为自由电子，当有足够多的电子从束缚电子电离成自由电子之后，就会出现大量电子和原子核相互作用的集体行为 , 成为整体电中性 , 而局域带电的特殊态 , 我们称处于该种状态的物质为等离子体态 , 由于等离子体态在地球的自然界中不能存在 , 一旦出现带电体 , 马上就会被中和掉 , 所以 , 在初、高中课本中没有出现这个态 , 但它的确是物质存在的第四态。 等离子体态大多存在于宇宙空间 , 地球上只有实验室里或极端天气情况下才会有等离子体的存在 , 太阳里没有固态、液态、气态物质的存在 , 因为那里的高温不允许中性物质存在 , 只有氢等离子体、氦等离子体等等。等离子体的特殊组成形成了它的特殊性质 , 最显著的行为之一就是等离子体的震荡 , 这是一个集体行为 , 处于正电的原子核和负电的电子若应若离 , 永不停息地震荡 , 而震荡所带来的等离子体频率是我们非常感兴趣，看看这个等离子体天线的装置图 : 照片来源 : http://www.groupsrv.com/science/post-2454354.html 这里的等离子体显然要被束缚在那根弯曲的管子 ( 玻璃管或者陶管 ) 里 , 要弄清楚等离子体天线发光的原理，首先让我们来看一下日光灯管的发光原理，在日光灯管两端加上强电压时，灯管两端的微细白热灯丝便会放出电子 , 电子从一端移至另一端，形成非中性等离子体。这些等离子体中的电子每秒能产生上百次的闪光（韧制辐射），发出肉眼看不见的紫外光 , 灯管中的水银，由于高温而蒸发成气体，由于灯光壁温度较低，他们会覆在灯管的内侧壁，这种带电的蒸气能将紫外线转换成为可见光 因此灯管发光。而在等离子体天线中等离子体的形成可能也类似于日光灯管中等离子体的形成（但具体技术手段可能是商业甚至国防秘密） , 所不同的是等离子体不仅发出紫外线，而且还要对外加电磁场做出响应 , 由等离子的基本性质可知，当等离子的振荡频率和电磁场的频率一致时，等离子体会在临界密度处有共振，使信号得以放大。而等离子体的振荡频率取决于等离子体的密度 , 它与电子的电荷和质量有关。我们知道，能够产生的等离子体往往不可能是均匀分布的，有一定的密度梯度和密度范围 , 如果知道最大的密度，我们就可以知道相应的等离子体振荡频率，因而也就知道了等离子体所能响应的最大电磁波频率。低于此频率的电磁波，由于等离子体中有相应的密度区域存在，因而也能做出响应；但如果电磁波频率超过了此范围，等离子体中没有这么高的密度，因而不能做出响应。 等离子体天线的工作原理大致可以总结如下，等离子体天线，一般来说由内部填充了一定气体的玻璃管或者陶管所组成，通过将其内部的气体电离从而使天线处于工作状态，在电离过程中可以对调控气体的密度，控制电磁场对其结构进行动态重构，使其适应不同的传输频率，方向，增益，传输带宽等，因此一个等离子天线可以承担几个不同的金属天线的功能，使得组建天线阵列所需的天线数量大大减少，其体积和重量也一并减少。相对于金属天线，等离子天线可以不需要很大的体积就可以进行低频信号的传输（注：传统金属天线需要尺寸与所传输或接受信号的波长相当，这里我们猜测等离子体天线进行低频信号传输的时候应该是利用等离子体自身的电磁震荡进行传输，否则按照传统天线理论，天线的尺寸应该只与所需传输信号的波长相关。）同样由于等离子的性质，等离子天线将只会对低于或等于等离子体本身震荡频率的电磁波进行响应，高于该频率的电磁波，将可以自由穿过等离子体天线，并不会对等离子天线产生影响，从而大大降低了等离子天线之间的干扰。 综合上述性质，一方面等离子天线在不工作的时候只是一些填充了气体的玻璃管或者陶管，使其不会被对方的雷达所发现。伴随着天线数量的减少，也极大地消除了天线之间彼此的干扰，并且较难被对方的雷达发现，所以等离子天线十分适合与军事用途。另一方面对于组建同样天线阵列，等离子天线需要的天线数量较少，从而是天线阵列的体积和重量大大降低，容易被应用在移动设备之上。 《中国科技信息》2008年第2期第269页.
标签: 等离子体
