# Plasma and Fusion Research

## Volume 9, 3401026 (2014)

# Regular Articles

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

### Abstract

A magnetosonic shock wave propagating obliquely to an external magnetic field can trap and accelerate electrons to ultrarelativistic energies when v_{sh} is close to c cos θ, where v_{sh} is the propagation speed of the shock wave, c is the light speed, and θ is the propagation angle of the shock wave.
Because of instabilities driven by the trapped electrons, some electrons can be detrapped from the main pulse retaining their high energies and can then be further accelerated to higher energies as a result of their gyromotions.
The dependence of electron motions on the parameters v_{sh} and θ is investigated by two-dimensional electromagnetic particle simulations with full ion and electron dynamics.
If θ is fixed, electron energies become maximum when v_{sh} is slightly smaller than c cos θ.
If the value of v_{sh}/(c cos θ) is fixed, the maximum energy of electrons tends to increase with decreasing θ for the range v_{sh}/(c cos θ) < 1.
The number of electrons that are detrapped to the upstream region and suffer the subsequent acceleration is also examined.

### Keywords

particle acceleration, collisionless shock, trapping, detrapping, particle simulation

### Full Text

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This paper may be cited as follows:

Mieko TOIDA and Junya INAGAKI, Plasma Fusion Res. 9, 3401026 (2014).