On the drift mechanism for energetic charged particles at shocks

Abstract

An adiabatic treatment is applied to the analysis of the energy changes of energetic charged particles, at a plane shock, which are caused by the 'drift' mechanism. The analysis indicates that in the case of a fast MHD shock, particles lose energy due to the acceleration drift in the magnetic field at the shock, with the drift velocity being antiparallel to the electric field. They then gain energy, because of the gradient drift parallel to the electric field. Particles whose pitch angles are aligned along the magnetic field are shown to lose energy due to acceleration drift as they pass through the shock, while those with pitch angles nonaligned to the magnetic field gain energy through gradient drift. Particles reflected by the shock always gain energy.