Accession Number:

ADA315316

Title:

Effect of Coulomb Collisions, Landau Damping and Particle Trapping on Linear and Nonlinear Ion Aooustic Waves.

Descriptive Note:

Final rept. 12 Mar 92-31 Dec 95,

Corporate Author:

NORTHEASTERN UNIV BOSTON MA DEPT OF ELECTRICAL ENGINEERING

Personal Author(s):

Report Date:

1996-04-30

Pagination or Media Count:

36.0

Abstract:

The general propagator expansion method is used for the study of the collision effects and the Fokker-Planck kinetic equation is employed for several collisional processes. In drift-free plasma, the studies show that the plasma may become unstable if e-i collision growth can overcome Landau damping and other collision damping. The contamination can affect ion acoustic waves significantly and a small amount of light ion contamination can cause much higher damping. For our experiment on the ion acoustic waves in drift-free plasma, the experimental results are explained with the consideration of collision and contamination effects and are close to our theoretical results.For a plasma with a quasi-static electric field, two ion acoustic modes may propagate in a single ion species plasma. This ion-acoustic instability associated with the slow mode is a kinetic instability and is caused by the interaction of ions and electrons. In our experiment, the fast mode is found and the measured results agree with the theoretic values. In a two-on-species plasma, the velocity differences between the ion species can cause the ion-ion two-stream instability. This is a fluid instability and only exists in a range of ion drift velocities and wave frequencies. An experiment was performed to study ion-ion two-stream instability. The unstable waves generated by the ion beams are observed as predicted by theory and coincide with the kinetic dispersion relations for the ion-ion two stream instability.

Subject Categories:

  • Plasma Physics and Magnetohydrodynamics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE