Laser Acceleration of Relativistic Electrons Using the Inverse Cherenkov Effect

Abstract

A 580-MW peak power, radially polarized C${\mathrm{O}}_{2}$ laser beam ($\ensuremath{\lambda}=10.6$ \ensuremath{\mu}m) focused by an axicon accelerated 40-MeV electrons by \ensuremath{\le}3.7 MeV over a 12-cm interaction length (31 MeV/m), using the inverse Cherenkov effect in which a gas is used to slow the light wave. This represents the first direct observation of acceleration using this effect and demonstrates the effectiveness of the radially-polarized-axicon-focused geometry. The observed energy gain agrees with model predictions.