  Different electron acceleration regimes in the evanescent field of a surface
plasma wave are studied by considering the interaction of a test electron with
the high-frequency electromagnetic field of a surface wave. The
non-relativistic and relativistic limits are investigated. Simple scalings are
found demonstrating the possibility to achieve an efficient conversion of the
surface wave field energy into electron kinetic energy. This mechanism of
electron acceleration can provide a high-frequency pulsed source of
relativistic electrons with a well defined energy. In the relativistic limit,
the most energetic electrons are obtained in the so-called electromagnetic
regime for surface waves. In this regime the particles are accelerated to
velocities larger than the wave phase velocity, mainly in the direction
parallel to the plasma-vacuum interface.
