摘要:

Thermal equilibrium properties are calculated for a cylindrical, pure electron plasma confined radially by a uniform axial magnetic fieldB0ez. In the weak coupling approximation (e2/nˆe−1/3≪kBTe), the one‐particle thermal equilibrium distribution function isfeq(H,P&thgr;)=const.. ×exp{−(H‐&ohgr;rP&thgr;)/kBTe}, whereHis the energy,P&thgr;is the canonical angular momentum,Teis the temperature, and &ohgr;ris the equilibrium angular rotation velocity of an electron fluid element. The self‐consistent equilibrium density profileneq(r)=Fd3pfeqis characterized over a wide range of values of the on‐axis electron density (nˆe), electron temperature (Te), and confining field strength (BO).Closed analytical expressions are derived for the mean‐square radius ⟨r2⟩eqof the plasma column and the angular rotation velocity &ohgr;r, expressed in terms of the nonlinear conservation constraints,Ne=∫d2x∫d3pP&thgr;fe(x,p,t)=const. and ⟨P&thgr;⟩=Ne−1∫d2x∫d3pP&thgr;fe(x,p,t)=const.,which correspond to the total number of electrons per unit axial length and the total canonical angular momentum per unit axial length, respectively. Finally, an exact power‐series solution is derived for the thermal equilibrium density profileneq(r) as a function of the radial distancerfrom the axis of the plasma column. © 1994American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.46751

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

A brief introduction to the interaction of ultra‐intense laser pulses with plasmas is presented. A number of interesting phenomena due to relativistic electron dynamics are reviewed in simple calculations. These relativistic effects range from nonlinear frequency shifts of light waves to penetration of overdense plasmas, filamentation and self‐focusing. Finally, computer simulations are used to illustrate several strongly nonlinear effects in such plasmas, including heating by the oscillating ponderomotive force and relativistic filamentation. © 1994American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.46749

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

The aim of this paper is to report on some recent studies that were performed in order to further extend the understanding of the late time evolution of the Rayleigh‐Taylor (RT) instability. We report results on: a) Two‐dimensional nonlinear interaction of a small number of modes: b) Three‐dimensional single mode and two‐mode‐coupling evolution as compared with 2D nonlinear results: c) RT evolution in three‐dimensional spherical geometry under conditions relevant to intertial confinement fusion targets. (AIP)American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.46753

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

It is a great pleasure for me to speak at this symposium in honor of Tom Stix. I have had the privilege of knowing Tom ever since I started working in plasma physics and fusion at the Princeton Plasma Physics Lab almost 36 years ago. He was a leader of the fusion effort when I arrived and has remained so up to the present time. I vividly remember our interesting discussions on plasma physics. Particularly, I remember how many new and original ideas came from Tom, his ideas for ICRH: the Stix coil, the magnetic beach, and many, many others. Tom not only originated ideas but he built and carried out experiments to these ideas, as well as many other fundamental concepts in plasma physics. Tom’s experiments were always firsts, and many pioneering advances were made by him. Tom’s enthusiasm for plasma physics and fusion is infectious; it stimulates and inspires his co‐workers and has touched all of Princeton’s plasma students. Tom has had a deep interest in teaching plasma physics from the beginning. His excellent course on plasma waves launched many careers. His book on plasma waves, which came from this course, is the standard on the subject, and is an invaluable reference for everyone working in plasma physics. Tom is a generous and caring person which made him an ideal person to lead the Princeton Plasma Physics Graduate Program. It is my great good fortune to have known and worked with Tom, and to have him as a friend.This symposium is particularly honoring Tom for his guiding of the graduate program in plasma physics at Princeton. For this reason I thought it would be appropriate for me to speak about some work a graduate student of mine, Bill Nunan, is doing, at UCLA. In a real sense the UCLA graduate program in Plasma Physics has many roots in the Princeton program which Tom so skillfully guided. ©American Institute of Physics 1994

ISSN:0094-243X    

DOI:10.1063/1.46746

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

Chlorine atoms released from CFCs by solar Ultraviolet (UV) radiation and from natural sources, are effective catalytic agents for the destruction of stratospheric ozone. Research into large‐scale mitigation methods is based on charging the chlorine radical, converting it into negative ions of low reactivity. Generation of charges‐and subsequent removal of chlorine ions by atmospheric platforms and electromagnetic waves are described. This method is generally applicable to all halogens. This research is guided by the principle that the solution should be as non‐intrusive environmentally as possible; i.e. no chemicals are to be injected. The large‐scale mitigation requires the process to be energy efficient and to utilize energy sources already present in the atmosphere. Because of the wide variety of remediation concepts, each is being tested using a combination of laboratory and field experiments together with computer modeling. The first laboratory demonstration of ozone depletion and subsequent recovery due to charge injection is presented. ©American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.46747

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

The fundamental theory of plasma heating by the fast magnetosonic wave in toroidal plasma configurations is reviewed and extended. The particular wave damping processes considered include cyclotron damping at the fundamental ion cyclotron frequency and its harmonics, and electron Landau damping and transist time magnetic pumping (TTMP). The latter processes heat electrons and may also be exploited to drive toroidal plasma currents. The wave absorption and damping decrements are obtained by using Stix’s approach, namely by computing the dissipated power,Re(J¯⋅E¯) in terms of the hot plasma dielectric constant (whereJ¯ is the wave induced current).This approach is compared with power absorption calculations from quasi‐linear theory, and exact agreement is found for a Maxwellian distribution of particles. Wave absorption in the presence of a small group of energetic particles is also examined for all three types of damping processes. The limitations of theory owing to mode conversion phenomena are indicated. Finally, a brief discussion of recent experimental results is given, verifying the reality of Landau damping of magnetosonic waves by electrons.

ISSN:0094-243X    

DOI:10.1063/1.46754

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

Tom Stix has made many major contributions to the development of understanding of a wide array of rf heating and diagnostics methods, in experiment and theory. In recognition of his profound influence on ion cyclotron range of frequencies (ICRF) heating research, this paper is focused on two major building blocks contributed by him which served to help guide and quantify the research toward establishing ICRF heating as a viable technique for the reactor regime: 1) the formalism for quantitative evaluation of antenna loading contained in his 1962 text book and 2) his Fokker‐Planck analysis for heating of ions and especially minority species ions in his 1975 Nuclear Fusion paper. Importantly, his work from the mid 1950s to the mid 1970s from which these two building blocks derive, provided a solid basis for the rapid developing ion cyclotron heating research in the 1970s and helped to guide that research to definitive demonstration of the viability of the minority ion heating regime as a reactor heating method by the end of the decade.

ISSN:0094-243X    

DOI:10.1063/1.46748

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

The problem of a weak source of particles that forms a distribution function that is unstable to a discrete number of modes with the electrostatic bump‐on‐tail instability taken as a paradigm is considered. Over a wide range of parameters the system produces pulsations, where there are relatively brief bursts of waves separated by longer intervals of quiescent behavior. There are two types of pulsations; benign and explosive. In the benign phase, valid when particle motion is not stochastic, the distribution function is close to that predicted by classical transport theory, and the instability saturates when the wave trapping frequency equals the expected linear growth rate.If the field amplitude reaches the level where orbit stochasticity occurs, the particle diffusion leads to a further conversion of the distribution’s free energy to wave energy. This leads to a rapid quaslinear relaxation (a phase space explosion) of the distribution function. Hence the overall response of the system is characterized by a relatively long time interval where the source needs to build up the distribution to its unstable shape as well as provide a sufficient amount of free energy for the instability to grow to the stochastic threshold of particle motion. The particle distribution is then flattened by the quasilinear diffusion in a relatively short time interval to regenerate the cycle. © 1994American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.46755

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

The MHD Rankine‐Hugoniot conditions relate uniform, stationary, dissipation free states of local thermodynamic equilibrium asymptotically far upstream and downstream of the shock. When particle collisions provide the shock dissipation full thermodynamic equilibrium can be achieved downstream. In collisions plasma, the shock dissipation will have to be provided by collective process. Several such processes are expected to occur and to have different scalelengths. Rankine‐Hugoniot relatives apply only to states separated by a distance greater than the longest scalength of all the processes needed to achieve local thermodynamic equilibrium downstream.(AIP)©American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.46750

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

The analytic properties of the drift plasma dispersion function are studied in detail via extending the bivariated normal probability function to the complex plane with analytic continuation. The recurrence relations are derived. Some limiting cases are discussed. It is useful for studying the collisionless kinetic responses, e.g., instabilities driven by magnetic field inhomogeneities, and/or weak relativistic effects in anisotropic plasmas. © 1994American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.46752

出版商:AIP    

年代:1994

数据来源: AIP