HR: 17:15h
AN: SH44C-06    [Abstracts]
TI: Instabilities in the Foot Region of Quasi-Perpendicular Shocks: Full Particle Electromagnetic Simulations
AU: * Scholer, M
EM: mbs@mpe.mpg.de
AF: Max-Planck-Inst. extraterrestr. Physik, P.O. Box 1312, Garching, 85741, Germany
AU: Comisel, H
EM: comisel@venus.nipne.ro
AF: Institute for Space Sciences, Bucharest-Magurele, Bucharest, 077125, Romania
AU: Matsukiyo, S
EM: matsuki@esst.kyushu-u.ac.jp
AF: ESST Kyushu University, 6-1 Kasuga-Koen, Kasuga, 816-8580, Japan
AB: We have investigated quasi-perpendicular collisionless shocks by one-dimensional full particle simulations in order to determine the instabilities in the foot region in various parameter regimes. Due to specularly reflected ions in the foot there is free energy in the relative streaming of incoming and reflected ions, of incoming electrons and reflected ions, and of incoming ions and incoming electrons. The main instabilities expected are the Buneman instabilty (BI) and the modified two-stream instability (MTSI). In addition, phase standing whistler waves may be radiated upstream from the ramp and stand in the foot. The problem with identifying instabilities occuring in the foot region of collisionless shocks in PIC simulations is that low ratios of the electron plasma to electron gyrofrequency suppress the BI, whereas low ion to electron mass ratios suppress the MTSI. Having both ratios at the physical value is presently computationally not feasable. By making an appropriate compromise we can investigate both instabilities as well as the phase standing whistler waves at the same time and we determine their influence on the shock reformation process at different Mach numbers and shock normal - magnetic field angles. In Particular we will investigate the consequences for self-reformation at very high Mach numbers (M_A>20).
DE: 2154 Planetary bow shocks
DE: 2159 Plasma waves and turbulence
DE: 7829 Kinetic waves and instabilities
DE: 7851 Shock waves (4455)
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Fall Meeting