Optical injection through collisions of laser pulses

John Cary
University of Colorado

The accelerating gradient of laser generated wake fields can
be orders of magnitude greater than the gradients obtainable
in traditional, rf structures. However, one must now
develop methods for reliable, stable injection into these
wake fields in order to obtain high-energy beams with narrow energy spread. Pulses colliding in a number of different configurations have been proposed. In this talk we examine the obliquely colliding pulses using the versatile plasma simulation application code, VORPAL [1]. Through such simulations we have been able to predict the variation of the beam with both timing and aiming errors. In addition, we have considered the damping induced by propagation in plasma channels. We consider a series of simulations with varying pulse length and width, but with overall power constant. For each simulation we match the width to the channel radius for optimum guiding, and we match the length to the plasma frequency at the bottom of the channel. We show that below a certain prolateness, optical injection produces multiple beams. Above that prolateness, single, clean beams emerge.

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