Two-Dimensional Study of Electron-Ion Streaming Instabilities.
NAVAL RESEARCH LAB WASHINGTON D C
Pagination or Media Count:
The authors present a two-dimensional study, based on computer simulation, of strong electron-ion streaming instabilities induced by counter-streaming ion beams, for initially cold electrons v sub e mach v sub d. Wave growth agrees well with linear theory initially. Higher harmonics appear later, in good agreement with mode coupling theory. The wave spectrum, initially very broad perpendicular to the streaming direction, narrows as the electrons heat and the waves saturate, in accordance with quasi-linear theory. Electron heating is explained by non-resonant quasi-linear diffusion at early times, and by resonant turbulent diffusion at later times. In contrast to previous one-dimensional studies, the authors found that electron heating continues well after wave saturation and after v sub e v sub d. However the heating rate at late times is somewhat reduced by partial plateau formation in the electron velocity distribution. Coherent electron trapping is not seen, as it is in the one-dimensional situation, but coherent ion trapping does occur and dominates the wave dynamics at late times, terminating wave growth on the time scale studied. Author
- Plasma Physics and Magnetohydrodynamics