Studies of Intense Laser Pulses Propagating in Plasma Channels

The numerical Simulation Code WAKE (P. Mora and T. M. Antonsen, Phys Plasmas 4, 217 (1997).) is applied to the study of laser pulse propagation in preformed plasma channels. Issues addressed are the focussing of the laser pulse in the presence of a large plasma wave disturbance, the possible excitation of Raman instabilities, the refraction of laser energy by ionization of ambient gas, and the determination of the group velocity of the laser pulse. Parameters chosen for the study will include both those relevant to the channel guiding experiment at UMD and to possible future experiments. The existing code makes use of the quasi-static approximation, which limits its applicability to the simulation of electrons with energy below about 1 MeV. An extension to the code that lifts this restriction will be discussed.