All Optical Accelerator Experiments at Lbnl⁄

An overview is presented of the status of laser wakefield acceleration research at the l’OASIS laboratory of the Center for Beam Physics at LBNL. Experiments have been performed on laser driven production of relativistic electron beams from plasmas using a high repetition rate (10 Hz), high power (10 TW) Ti:sapphire (0.8 „m ) laser system. Large amplitude plasma waves have been excited in the self-modulated laser wakefield acceleration regime by tightly focusing (spot diameter 8 „m ) a single high power (up to 10 TW), ultra-short (‚ 50 fs) laser pulse onto a high density (> 1019 cm¡ 3) pulsed gasjet of length 1.2 mm. Nuclear activation measurements in lead and copper targets indicate the production of electrons with energy in excess of 25 MeV. This result was confirmed by electron distribution measurements using a bending magnet spectrometer. Progress on implementing the colliding pulse laser injection method is also presented. This method is expected to produce low emittance (< 1... mm-mrad), low energy spread (< 1% ), 40 MeV femtosecond duration electron bunches containing 107 electrons/bunch.