Scientific and Technical Aerospace Reports Volume 38 July 28, 2000

20000063524 Compton Research and Development Labs., Inc., Staten Island, NY USA
Self-Field-Dominated Plasma Final Report, 1 Apr. 1995 - 31 Mar. 1998
Nardi, V.; Brzosko, J. S.; Powell, C.; Mar. 31, 1998; 20p; In English
Contract(s)/Grant(s): F49620-95-1-0271; AF Proj. 2301
Report No.(s): AD-A376917; AFRL-SR-BL-TR-00-0167; No Copyright; Avail: CASI; A03, Hardcopy; A01, Microfiche
This research effort addresses the production process of ion clusters with binding energy per ion as low as = 2.78 eV from
a plasma source characterized by high energy density (kJ/cu cm, i.e., 0.2 keV/particle) and electron temperatures T(e) 0.4 keV.
Particle-flow and magnetic structure of the plasma current sheath affect the emission of ion clusters and superclusters in plasma
focus discharges. Part of the tests summarized here address methods and means for achieving controlled variations of the current
sheath (CS) structure via electrode geometry modifications. CS parameters are monitored with multiple magnetic probes in the
case of cylindrical - and open-funnel electrode geometry.
DTIC
Electron Energy; Ions; Magnetic Probes; Plasma Currents; Plasma Focus; Plasmas (Physics)
20000064707 Risoe National Lab., Optics and Fluid Dynamics Dept., Roskilde, Denmark
Flow speed measurement using two-point collective light scattering
Heinemeier, N.; Sep. 30, 1998; 144p; In English
Report No.(s): DE99-609083; RISO-R-1064(EN); ISBN 87-550-2413-0; No Copyright; Avail: Department of Energy Information
Bridge
Measurements of turbulence in plasmas and fluids using the technique of collective light scattering have always been plagued
by very poor spatial resolution. In 1994, a novel two-point collective light scattering system for the measurement of transport in
a fusion plasma was proposed. This diagnostic method was design for a great improvement of the spatial resolution, without sacrificing
accuracy in the velocity measurement. The system was installed at the W7-AS steallartor in Garching, Germany, in 1996,
and has been operating since. This master thesis is an investigation of the possible application of this new method to the measurement
of flow speeds in normal fluids, in particular air, although the results presented in this work have significance for the plasma
measurements as well. The main goal of the project was the experimental verification of previous theoretical predictions. However,
the theoretical considerations presented in the thesis show that the method can only be hoped to work for flows that are almost
laminar and shearless, which makes it of very small practical interest. Furthermore, this result also implies that the diagnostic at
W7-AS cannot be expected to give the results originally hoped for.
NTIS
Flow Measurement; Velocity Measurement
20000065670 Texas Univ., Inst. for Fusion Studies, Austin, TX USA
Nonlinear theory of kinetic instabilities near threshold
Berk, H. L.; Pekker, M. S.; Breizman, B. N.; May 31, 1997; 31p; In English
Report No.(s): DE97-008140; DOE/ER/54346-787; IFSR-787; No Copyright; Avail: Department of Energy Information Bridge
A new nonlinear equation has been derived and solved for the evolution of an unstable collective mode in a kinetic system
close to the threshold of linear instability. The resonant particle response produces the dominant nonlinearity, which can be calculated
iteratively in the near-threshold regime as long as the mode does not trap resonant particles. With sources and classical relaxation
processes included, the theory describes both soft nonlinear regimes, where the mode saturation level is proportional to an
increment above threshold, and explosive nonlinear regimes, where the mode grows to a level that is independent of the closeness
to threshold. The explosive solutions exhibit mode frequency shifting. For modes that exist in the absence of energetic particles,
the frequency shift is both upward and downward. For modes that require energetic particles for their existence, there is a preferred
direction of the frequency shift. The frequency shift continues even after the mode traps resonant particles.
NTIS
Nonlinear Equations; Kinetics
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