HR: 1340h
AN: SM23B-0418    [Abstracts]
TI: Single-particle Motion and Collective Plasma Dynamics in Thin Current Sheets: Guide Field Effects
AU: * Dunstan, R
EM: dunstanr@etown.edu
AF: Elizabethtown College, 867 Baugher Ave., Elizabethtown, PA 17022 United States
AU: Sitnov, M I
EM: sitnov@umd.edu
AF: Institute for Research in Electronics and Applied Physics, University of Maryland, Energy Research Facility (Bldg. #223) Paint Branch Drive, University of Maryland, College Park, MD 20742-3511 United States
AU: Guzdar, P N
SM23B-0418 AF: Institute for Research in Electronics and Applied Physics, University of Maryland, Energy Research Facility (Bldg. #223) Paint Branch Drive, University of Maryland, College Park, MD 20742-3511 United States
AU: Swisdak, M M
SM23B-0418 AF: Icarus Research Inc., P. O. Box 30780, Bethesda, MD 20824-0780 United States
AB: The influence of the magnetic field component parallel to the equilibrium current direction (guide field) on the non-adiabatic particle dynamics as well as on the features of current-driven instabilities in thin current sheets is explored. The properties of thin current sheets with the thickness comparable to the thermal ion gyroradius in the field outside the sheet may be very sensitive to the features of the single-particle motion, and in particular to its type (regular, chaotic or quasi-adiabatic). Simple criteria of the particle motion type, based on the comparison of the particle minimum Larmor frequency and the maximum bounce frequency, may be misleading in the presence of the guide field. We reconsider this issue and show, in particular, that the particle dynamics may remain quasi-adiabatic notwithstanding a considerable guide field. The guide field formally disappears from the steady-state Vlasov models of both the Harris current sheet and its generalizations assuming plasma anisotropy and non-gyrotropy. Therefore, this field can readily be included in particle simulations starting from these models. On the other hand, the guide field strongly affects the dynamics of thin current sheets. We report on the results of such simulations of current-driven instabilities in thin Harris sheets and their anisotropic/non-gyrotropic generalizations. The simulation results are compared with Cluster observations.
DE: 2744 Magnetotail
DE: 2764 Plasma sheet
DE: 2772 Plasma waves and instabilities (2471)
DE: 4420 Chaos (7805)
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005