Reflection of Charged Particles by Plasma Shocks

This paper investigates the reflection and transmission of charged particles incident on a plane moving plasma shock whose thickness is small compared to the Larmor radius of the particles. When the intersection with the shock moves along the field lines with velocity > c the particles are transmitted and their magnetic moment is conserved. For all other cases, conditions for reflection and transmission are found and numerical results are obtained by computing particle paths. For small differences in field strength the adiabatic invariant holds approximately, but for larger differences the particles are scattered widely both on reflection and on transmission. These results are applied to possible Fermi mechanisms for accelerating cosmic-ray particles.