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LIST OF AGENCIES CONTACTED 199 C List of Agencies Contacted National Science Foundation Physics Division Astronomical Sciences Division Atmospheric Sciences Division Electrical and Communications Systems Division (Quantum Electronics Waves and Beams Program) Office of Polar Programs (Polar Aeronomy and Astrophysics Program) National Aeronautics and Space Administration Space Physics Division Astrophysics Division Solar System Exploration Division (Planetary Science Branch) Goddard Space Flight Center Department of Energy Office of Basic Energy Sciences Office of Fusion Energy Office of Defense Programs (Office of Inertial Fusion) Office of Naval Research Army Research Office Air Force Office of Scientific Research Air Force Cambridge Research Laboratory (Ionospheric Physics Laboratory) NOTE: In some cases letters were sent to multiple offices or programs within those listed above.
LIST OF AGENCIES CONTACTED 200
LIST OF AGENCIES CONTACTED PLATE 1 Three 82-mm-diameter silicon wafers are shown during plasma processing in a plasma reactor used for the transfer of fine-line features during electronic chip fabrication. The bright regions above the wafers are clouds of fine particles, illuminated by argon laser light. This ''dust" is a critical source of defects in chip manufacture, and techniques are now being developed to eliminate it. (Courtesy of G. Selwyn, Los Alamos National Laboratory; work performed at IBM, Yorktown Heights, N.Y.) 201
LIST OF AGENCIES CONTACTED PLATE 2 Relaxation and self-organization of turbulence in a magnetized pure-electron plasma, showing the time evolution of fine-scale vorticity into one large vortex. These electron plasmas are nearly ideal, inviscid, two-dimensional fluids, in which electron density plays the role of vorticity. They permit studies of two-dimensional fluid dynamics not possible in conventional fluid systems. Shown is the evolution of electron density, as time proceeds, from left to right; violet corresponds to high electron density (i.e., vorticity) and red to low density. (Courtesy of C.F. Driscoll, University of California, San Diego.) 202
LIST OF AGENCIES CONTACTED PLATE 3 An ICF hohlraum (a thin tungsten cylinder 2.8 mm long and 1.6 mm in diameter) is illuminated by the 10 beams (in blue) of the Nova laser, which enter through small holes in the hohlraum. In this approach to inertial confinement fusion, intense x-rays with energies of several hundred electron volts are generated and trapped in the hohlraum when the laser beams heat its interior walls. These x-rays uniformly heat the ICF target. In this figure, the laser beams, hohlraum, and stalk are the artist's conception. The orange spots are actual experimentally measured x-ray emission from the hohlraum walls. The laser beams have a wavelength of 0.35 Âµm. The spots are each approximately 0.7 mm by 0.3 mm. (Courtesy of F. Ze, S. Wilks, and S. Dougherty, Lawrence Livermore National Laboratory.) 203
LIST OF AGENCIES CONTACTED PLATE 4 X-ray laser interferogram of a mylar target irradiated with 1.5 Ã 1014 W/cm2 by one beam of the Nova laser. To produce this image, an x- ray laser operating at a wavelength of 155 Ã , with a pulse duration of 150 ps, was combined with a Mach-Zehnder interferometer consisting of multilayer mirrors and multilayer-coated silicon-nitride beamsplitters. Compared to conventional optical interferometry, the short wavelength of the x-ray laser makes it possible to probe much larger and higher-density plasmas with micron resolution. In this image, one fringe shift corresponds roughly to an electron density of 1.5 Ã 1020 cm-3 for a plasma length of 1 mm. The bright region is self-emission from the laserheated plasma. (Courtesy of Luiz Da Silva, Lawrence Livermore National Laboratory.) 204
LIST OF AGENCIES CONTACTED PLATE 5 Computer model of Earth's plasma environment, obtained by solving the single-fluid magnetohydrodynamic equations on a supercomputer. This computation illustrates the breadth of phenomena that can be simulated using contemporary hardware and software. The terrestrial magnetic field lines are compressed and confined on the sunward side by the solar wind, which flows in from the left (i.e., the day side) and is drawn out into a long magnetotail at night. Note the presence both of magnetic field lines connected to Earth and of lines that are completely disconnected, and the juxtaposition of the two at points, both day and night, where magnetic reconnection presumably occurs. Coloring denotes relative plasma pressure, which is high (red) in the interface region with the solar wind (the magnetosheath) and in the near-Earth nightside (the plasma sheet) and is very small (blue) in the distant tail lobes. The size of Earth has been artificially magnified so that the distribution of aurorae, which are proportional to the incident plasma flux, is readily discernible. (Courtesy of J. Raeder, University of California, Los Angeles.) 205
LIST OF AGENCIES CONTACTED PLATE 6 Laboratory experiment illustrating the nonlinear phenomena resulting from the propagation of whistler waves into a density striation. The auroral ionosphere contains field-aligned density depressions with many scale sizes. The ionospheric plasma has been observed to contain a great deal of whistler-wave activity, as well as ion and electron acceleration and electrostatic waves. In this laboratory experiment, a striation 10 m long and 4 cm in diameter (magenta) is created by non-uniform electron emission from a cathode (orange square). Magnets, which produce a uniform axial magnetic field, are shown surrounding a cutaway view of the chamber. Whistler waves are launched from a loop antenna, which is also shown. (a) Wave magnetic field data (red crests, blue troughs) taken in a plane above the striation agree well with the predicted pattern. (b) Data in a plane containing the striation show a highly distorted pattern. (c) When long perpendicular wavelengths are filtered out, mode-converted, short-wavelength lower-hybrid waves appear. (Reprinted, by permission, from J.F. Bamber, W. Gekelman, and J.E. Maggs, Physical Review Letters 73:2990, 1994. Copyright Â© 1994 by the American Physical Society.) 206
LIST OF AGENCIES CONTACTED PLATE 7 Images of the Sun in white light (left) and in soft x-rays (right) taken by the Yohkoh spacecraft in 1991, illustrating the importance of magnetic fields in solar phenomena. The white light shows that except for active regions, which are distinguished by sunspots, the Sun is essentially featureless at the 5000 K photosphere. However, as evidenced in the x-ray image, the million-degree corona exhibits a great amount of structure due to the influence of the magnetic field. The corona is most active over sunspot regions. At the poles, where the magnetic field is weak and open, x-ray emission is minimal. (Courtesy of Lockheed Palo Alto Research Laboratory, NASA, and the Institute of Space and Astronautical Science of Japan.) 207
LIST OF AGENCIES CONTACTED PLATE 8 Computer simulation of plasma turbulence in a tokamak plasma, using a gyrokinetic approximation and 1 million to 8 million particles. Radial and poloidal cross sections of the electrostatic potential are shown during the linear amplification phase. This picture highlights the radial elongation of the mode structure during saturation and the transition to turbulence. The colors represent the value of the potential, varying from positive to negative: magenta, violet, blue, green, yellow, red. (Reprinted, by permission, from S.E. Parker, W.W. Lee, and R.A. Santoro, Physical Review Letters 71:2042, 1993. Copyright Â© 1993 by the American Physical Society.) 208