The Plasma Beat Wave Accelerator - I Experiments

In the Plasma Beat Wave Accelerator, acceleration is achieved by a longitudinal electrostatic field produced as a result of charge separation generated by a plasma wave traveling close to the speed of light. The plasma wave in turn is produced by two colinear laser pulses whose amplitude is modulated so that the beat frequency matches the plasma frequency. Optical mixing and Raman forward scattering instability play a crucial role in the growth and nonlinear saturation of such high phase velocity plasma waves. In this paper we describe experiments that show, i) that long wavelength high phase velocity electron plasma waves can be generated in a homogeneous plasma by optical mixing and ii) relativistic particles are indeed generated by the Raman forward instability.