Plasma Physics Division Research Articles

Foreword: Papers from the 47th Annual Meeting of the APS Division of Plasma Physics, Denver, Colorado, 2005

Foreword: Papers from the 47th Annual Meeting of the APS Division of Plasma Physics, Denver, Colorado, 2005

Foreword: Papers from the 46th Annual Meeting of the APS Division of Plasma Physics, Savannah, Georgia, 2004

Foreword: Papers from the 46th Annual Meeting of the APS Division of Plasma Physics, Savannah, Georgia, 2004

The Harris magnetic field: A laboratory realization of the topology based on energy resonance

An often‐used approximation to the magnetotail field and the reconnection layer magnetic fields is the modified Harris field which consists of a neutral sheet magnetic field profile Bx(z) along with a superimposed normal field Bz. We have designed a configuration of current‐carrying conductors and Helmholtz coil fields aimed at producing the topological characteristics of this field. In addition to mapping the geometry of the field we have appealed to another criterion of validity of this simulation, the energy resonance phenomenon. Energy resonance is an essential feature of nonlinear particle dynamics in magnetotail‐like magnetic fields. The phenomenon is characterized by periodic peaks and valleys occurring in scattered particle distribution functions when plotted versus energy. The “neutral sheet” of the simulated field is not actually plasma current which self‐consistently is responsible for the magnetic field, but rather the field is produced by planar arrays of current carrying wires. For this reason certain self‐consistency requirements on particle orbits in such fields do not arise. Particle injection into the field region, which is formed by 4 conducting wire grids and an external constant field, is accomplished with a programmable electron gun with energies in the range 200 eV to 10 keV. The basic physics of the resonance phenomenon which occurs if the average radius of curvature of the field and the Larmor radius of injected particles are comparable, is scalable from the experiment to the magnetotail environment and has no dimensional dependence. The identification of the resonance effect itself arose from analysis of possible particle phase space orbits in Harris‐type fields. A result of this analysis was that the orbits are divided into clearly separate classes from which the resonance phenomenon follows. The creation of the field in the laboratory model includes realistic design considerations related to the method of producing the field. The design is based on using a test particle code which selects a source distribution of particles to “push” through the modeled magnetic field. Detailed test‐particle simulation investigates particle orbits and the effect on resonance of the finite thickness of conducting wires in addition to the finiteness of the apparatus itself. The experimental effort was performed in the large Space Physics Simulation Chamber (SPSC) in the Plasma Physics Division at the Naval Research Laboratory.

Foreword: Papers from the 45th Annual Meeting of the APS Division of Plasma Physics, Albuquerque, New Mexico, 2003

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Mini-conference and related sessions on laboratory plasma astrophysics

This paper provides a summary of some major physics issues and future perspectives discussed in the Mini-Conference on Laboratory Plasma Astrophysics. This mini-conference, sponsored by the Topical Group on Plasma Astrophysics, was held as part of the American Physical Society’s Division of Plasma Physics 2003 Annual Meeting (October 27–31, 2003). Also included are brief summaries of selected talks on the same topic presented at two invited paper sessions (including a tutorial) and two contributed focus oral sessions, which were organized in coordination with the mini-conference by the same organizers.

Mini-conference on laser-induced fluorescence in plasmas

A mini-conference on laser-induced fluorescence in plasmas was held on 29 October 2003 as part of the 45th meeting of the Division of Plasma Physics of the American Physical Society. This paper summarizes material discussed in the talks presented as part of the mini-conference. The mini-conference was also an occasion to honor Raul Stern on his 75th birthday and to recognize his many contributions to plasma physics and to the applications of laser-induced fluorescence.

Burton David Fried

Burton David Fried

Mini-conference on Hamiltonian and Lagrangian methods in fluid and plasma physics

A mini-conference on Hamiltonian and Lagrangian methods in fluid and plasma physics was held on 14 November 2002, as part of the 44th meeting of the Division of Plasma Physics of the American Physical Society. This paper summarizes the material presented during the talks scheduled during the Mini-Conference, which was held to honor Allan Kaufman on the occasion of his 75th birthday.

Brighter Omens for Giant Reactor?

FUSIONPITTSBURGH- A debate over whether turbulence would cause heat to leak from a prototype fusion reactor--the projected $10 billion International Thermonuclear Experimental Reactor (ITER)--received fresh fuel at a tense session of last week's meeting here of the American Physical Society's division of plasma physics. A new set of calculations suggests that fusion reactors like ITER would leak heat more slowly than predicted by the model that set off the debate last year. But nobody is ready to say that the results put ITER in the clear, as researchers have been unable to pinpoint why the predictions differ under some conditions.

Physicists Find Windows of Opportunity in Plasmas

The 1500 physicists from Europe, the United States, the Pacific Rim, and the former Soviet Union who gathered in Minneapolis from 7 to 11 November had many messages but one medium: plasmas. As the presentations at the meeting of the American Physical Society's division of plasma physics showed, the windows that laboratory plasmas can provide into space, turbulent liquids, and matter-antimatter interactions are opening wider than ever.

Plasma Physics Division: Call for Nominations

Plasma Physics Division: Call for Nominations

Controlled fusion and plasma heating (Report on the 17th European Conference, Amsterdam, The Netherlands, 25–29 June 1990)

The 17th European Conference on Controlled Fusion and Plasma Heating was held at the Free University of Amsterdam, under the auspices of the Plasma Physics Division of the European Physical Society (EPS). About 500 scientists attended the meeting. The programme included 18 invited papers; of the contributed papers, 24 were selected for oral presentation and 470 for poster presentation. Approximately 80% of the contributions concerned tokamak research.

Characterization of X-pinch plasma (abstract)

The X pinch, in which two or more crossed wires are stretched between the electrodes of the 0.5 TW LION accelerator, is being studied as a bright x-ray source for photopumping an extreme ultraviolet (XUV) laser and for microlithography. Crossed Al or Mg wires with line density from 10 to 400 μg/cm have been imploded by up to 550 kA current for 40 ns. High density and temperature bright spots have been observed at the crossing point. Diagnostics include x-ray pinhole cameras, streak and framing cameras, and XUV x-ray spectrographs. The visible streak camera provides time and radial (or axial) spatially resolved information on the pinch plasma, while the 5 ns single frame camera gives spatially resolved images. The size of the soft x-ray hot spots (less than 40 μm diameter) was estimated from the time-integrated pinhole image. An x-ray spectrograph with a curved mica crystal was used to record K-shell emission spectra. From the line intensity ratios of the K-shell radiation, plasma densities of ∼1020 cm−3 and temperatures about 400 eV were obtained. This work was supported in part by the Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375-5000, under ONR contract N00014-90-J-2002 and NSF grant 89-19960.

Authors

Authors

Space plasma branch at NRL

The Naval Research Laboratory (Washington, D.C.) formed the Space Plasma Branch within its Plasma Physics Division on July 1. Vithal Patel, former Program Director of Magnetospheric Physics, National Science Foundation, also joined NRL on the same date as Associate Superintendent of the Plasma Physics Division. Barret Ripin is head of the newly organized branch. The Space Plasma branch will do basic and applied space plasma research using a multidisciplinary approach. It consolidates traditional rocket and satellite space experiments, space plasma theory and computation, with laboratory space‐related experiments. About 40 research scientists, postdoctoral fellows, engineers, and technicians are divided among its five sections. The Theory and Computation sections are led by Joseph Huba and Joel Fedder, the Space Experiments section is led by Paul Rodriguez, and the Pharos Laser Facility and Laser Experiments sections are headed by Charles Manka and Jacob Grun.

Controlled fusion and plasma physics (Report on the 16th European Conference, Venice, Italy, 13–17 March 1989)

The 16th European Conference on Controlled Fusion and Plasma Physics was held at the Fondazione Cini, on the island of S. Giorgio Maggiore in Venice, 13–17 March 1989, on behalf of the Plasma Physics Division of the European Physical Society. Almost 600 scientists attended the meeting; 17 invited papers, 26 oral contributions and more than 400 poster contributions were presented.

Controlled Fusion and Plasma Physics Report on the 14th European Conference held in Madrid, Spain, 22-26 June 1987

The European Conference on Controlled Fusion and Plasma Physics, organized by the Plasma Physics Division of the European Physical Society, which, after having started three years ago, takes place annually in late spring, continues to reflect the major effort being put into developing controlled nuclear fusion in both eastern and western Europe. Major participation from the USA, Japan and Canada again emphasized the importance of this meeting. This year the conference was hosted by the Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Spain, and took place in the Palacio de Congresos y Exposiciones de Madrid. It was attended by about 500 participants from 25 countries.

Space science setbacks discussed

Making the best of a difficult situation seemed to be the recurring theme of a forum on the future of U.S. space science held earlier this month at the meeting of the American Physical Society's Division of Plasma Physics in Baltimore, Md. The loss of the space shuttle Challenger has had “immediate and very substantial” effects on space science, according to Jeffrey D. Rosendhal of the Office of Space Science and Applications at the National Aeronautics and Space Administration (NASA), one of four speakers at the forum.

A Theoretical Derivation of Resonant Absorption††This paper was first presented at the 25th Annual Meeting of the American Physical Society Division of Plasma Physics, No. 7-11, 1983, Los Angeles, California

The Problems of resonant absorption in laser-plasma interactions are analyzed by means of a new method. First, we obtain an analytical expression for the electromagnetic field structure of resonant absorption, which is valid for all regions of the coronal plasma and correctly reflects various fundamental features. Then, we derive the absorption coefficient in the form of an elementary function. The results are in excellent agreement with numerical calculations for all angles of incidence. This work extends previous results obtained by solving the wave equation.

Harmonic Emssions From Laser-Produced Plasmas††This paper was first presented at the 25th Annual Meeting of the American Physical Society Division of Plasma Physics, No. 7-11, 1983, Los Angeles, California.

Harmonic generation as a result of resonant absorption in laser-produced plasmas is investigated by considering the steepened plasma density gradients in the vicinity of the critical density. We obtained an efficiency of the second harmonic emission which is in better agreement with experiments than previous theories. The present calculation has also been extended to including the efficiency of the third harmonic emission, the results obtained indicate that at sufficiently high laser intensities, the third harmonic emission generated by the resonant absorption can also be observed.