Laser wakefield acceleration

The next generation of high energy particle accelerators needs to obtain energy gradients considerable higher than those obtainable from the present day conventional accelerators. The ultra high fields necessary may be induced and sustained in a plasma. This dissertation investigates some of the problems and possible cures associated with the production of such strong fields in a plasma by using a short laser pulse. First we propose the use of an active medium to overcome the problems of pump depletion of the laser pulse and dephasing of the particles and the accelerating fields associated with laser wakefield acceleration. We also investigate the new phenomena of a wakefield induced by an ionization front. The effects that the ionization of a gas to form a plasma has on the evolution of that laser pulse and the possibility of using a plasma channel to optically guide a laser pulse are discussed. Finally application of forward Raman scattering to modulate a laser pulse in the high density regime is investigated. Simulation results supporting the conclusion that a Japanese experiment conducted at KEK national labs of an intense laser pulse in a high density gas induced pulse modulation by the mechanism of forward Raman scattering are given. This is the first observation of accelerated electrons by modulated laser pulser induced wakefields.