Channeling and time evolution of laser wakes and electron acceleration in a self-modulated laser wakefield accelerator experiment

Large amplitude plasma wakefields produced by a high power laser pulse in an underdense plasma were studied in a self-modulated laser wakefield accelerator (SM-LWFA) experiment. A pump-probe coherent Thomson scattering (CTS) technique was used and the lifetime of the wakefield was measured to be less than 5 psec. A plasma channel was observed to form in the wake of the pump laser pulse. The trailing probe laser pulse was observed to be guided by this channel for about 20 Rayleigh lengths. High energy electrons (up to 30 MeV) have been measured using a magnetic spectrometer. Highly non-linear plasma waves were also detected using forward Raman scattering diagnostics and were observed to correlate with the electron signals.