Invited Paper Experimental Demonstration of Laser Acceleration of Electrons via Relativistic Plasma Waves

A two-frequency CO laser beam was used to beat-excite a large amplitude electron plasma wave in a resonant density plasma. The accelerating fields of the relativistic plasma wave were probed with collinear injected 2.1 MeV electrons from an electron linac. Some electrons gained at least 7 MeV in traversing the approximately 1 cm length of the beat wave accelerator, with the measurement limited by the 9. 1 MeV high energy cut-off of the detection system. The corresponding average acceleration gradient is>0.7 GeV/m and the average wave amplitude n I n is> 8%. Estimates based on collective Thomson scattering indicate that peak wave amplitudes of 15—30 % may have been achieved. 1