Experiments on the Plasma Beat-Wave Accelerator

We report an experimental study of the beat-wave excitation of plasma waves using a short pulse, high intensity CO
²
laser with two colinearly propagating beams to excite the fast wave (v
_p
Ƀ c) in a long-scale-length underdense plasma. Maximum plasma wave amplitudes n
₁
/n
₀
Ƀ 0.19 with effective longitudinal electric field gradients of Ƀ 6 GV/m over a distance of 0.5 mm were achieved in these experiments.