Effects of Electromagnetic Fluctuations along Shock Front on Electron Motions in an Oblique Shock Wave

Abstract

The evolution of a large number of electrons in a shock wave propagating obliquely to an external magnetic field is analyzed by means of a two-dimensional electromagnetic particle code. Furthermore, the motions of the same number of test electrons in the electromagnetic fields averaged along the shock front are calculated, that is, in the equation of motion for the test electrons, two-dimensional electromagnetic fluctuations with finite wave numbers along the shock front are excluded. A comparison of the two groups of electrons shows that the two-dimensional electromagnetic fluctuations, which grow up to large amplitudes because of whistler wave instabilities excited by electrons trapped in the main pulse region of the shock wave, can cause the detrapping of energetic electrons from the main pulse and their subsequent acceleration to much higher energies. It is also found that two-dimensional fluctuations can contribute to the reflection of electrons near the end of the main pulse.