Reflection and capture of a charged particle by a plane electromagnetic wave in a medium

A theoretical analysis is given of the interaction between a charged particle and a plane electromagnetic wave in a medium whose refractive index is n > 1. It is shown that when the wave field exceeds a certain critical value, a particle located outside the wave cannot penetrate it and a particle inside the wave cannot escape from it. If the initial conditions are such that the wave overtakes the particle, Cerenkov photons are absorbed at the critical point (the inverse Cerenkov effect takes place). Therefore, the energy of the particle increases and the particle detaches itself from the wave. However, if the particle overtakes the wave, the interaction results in a loss of energy by the particle and this energy is transferred to the wave in the form of stimulated Cerenkov radiation.