ELECTRON TRAPPING IN SELF-MODULATED LASER WAKEFIELDS BY RAMAN BACKSCATTER

Simultaneous measurements of high energy electrons and plasma-wave cha racteristics have been conducted in a self-modulated laser-wakefield a ccelerator. Approximately 10(8) electrons were accelerated from the ba ckground plasma to energies greater than 1 MeV with a peak energy of a pproximately 30 MeV. A strong correlation between the plasma-wave ampl itude and electron production was measured with no evidence of wave br eaking. Simulations indicate plasma electrons are trapped by the low-p hase-velocity beat waves produced by backward Raman scattering.