Temporal Evolution of Self-Modulated Laser Wakefields Measured by CoherentThomson Scattering

摘要

Coherent Thomson scattering of a picosecond probe laser was used to measure thetime evolution of plasma wakefields produced by a high intensity laser pulse (4 x 10(exp 18) W/cm2) in an underdense plasma (n sub e approx = 10(exp 19)/cc) in the Self Modulated Laser Wakefield Accelerator configuration. Plasma wakefields are observed to last for approximately 50 psec. Ion acoustic waves, generated by the decay of the plasma wakefield, were measured to have a duration of approximately 50 psec. These observations are consistent with the decay of large amplitude plasma waves due to the modulational instability and the enhancement of the scattered signal from plasma channel formation.