Relaxation of the shock wave‐reflected ion beam, and generation of hot electrons

Abstract

The results obtained with the collisionless shock wave (CSW) experiments on a laboratory device are presented. Ion beam relaxation regimes both in the region of main jump of the magnetic field (“ramp”) and in the zone occupied by the reflected ion flux are grouped into classes. Ahead of the magnetic front a reflecting hump of the electrostatic potential was recorded, which was formed by the ion beam reflected by potential jump in the magnetic ramp region. An electron acceleration effect in the ion‐ion interaction region ahead of the magnetic front to energies of about 100 initial electron temperatures was detected. Hot electrons propagate anomalously rapidly from this region across the magnetic field in the form of a localized disturbance. In the neighborhood of the ion reflection zone in the ramp region, a nonadiabatic heating of electrons to energies approaching the value of the electrostatic potential within the CSW was detected. Analysis of experimental results suggests that (1) the shock front structure is not in steady state and (2) the transverse magnetosonic shock wave in a collisionless plasma has the following common structural characteristics: hot electron region‐turbulent region, occupied by the reflected ion flux‐diffusion magnetic foot‐jump of plasma parameters and the magnetic field (ramp region)‐relaxation region behind the shock front. Implications of experimental results obtained in this study to the Earth's magnetosphere physics are discussed.