PARTICLE-ACCELERATION BY LARGE-AMPLITUDE WAVES REVISITED

We reconsider the problem of particle acceleration by large-amplitude electromagnetic waves. We make use of a fully relativistic Hamiltonian formalism to show that, as opposed to nonelativistic results obtained by Kuo and Lee, acceleration in unmagnetized systems is severely arre sted when the phase velocity of the electromagnetic mode approaches th e speed of light. For subluminal waves, however, acceleration is shown to be still effective.