Cyclotron acceleration of charged particles in a plasma

An averaging method is used to analyze the motion of a charged particle in an external magnetic field and in a plane monochromatic wave propagating in a plasma under cyclotron-resonance conditions. Attention is focused on the weakly relativistic case and on the resonant interaction of the particle with a wave whose phase-velocity component along the external magnetic field is close to the speed of light in vacuum. The possibility of accelerating particles from a low initial energy to relativistic energies is analyzed.