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Repeated Acceleration of Thermal Ions by an Oblique Shock Wave and Associated Whistler Instabilities

Mieko TOIDA and Taku GOHIRA

Department of Physics, Nagoya University, Nagoya 464-8602, Japan

(Received 7 December 2009 / Accepted 27 February 2010 / Published 10 December 2010)

Abstract

A magnetosonic shock wave propagating obliquely to an external magnetic field can repeatedly accelerate thermal ions if θ0 45°C , where θ0 is the angle between the wave normal and the external magnetic field. The ion energy gains in this process are theoretically analyzed, and an expression for the maximum energy is derived. This theory is verified using a two-dimensional, electromagnetic particle code. Furthermore, whistler wave instabilities generated by the accelerated ions are studied. The simulation demonstrates that whistler waves are excited in both the upstream and downstream regions, but that the whistler waves in these two regions have different frequencies and wavenumbers. It is shown that the characteristics of these waves can be explained by linear theory.

Copyright (c) 2010 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

collisionless shock, ion acceleration, whistler wave instability, particle simulation

DOI: 10.1585/pfr.5.S2065

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This paper may be cited as follows:

Mieko TOIDA and Taku GOHIRA, Plasma Fusion Res. 5, S2065 (2010).