Pump Depletion and Laser Staging for Beat-Wave Accelerator

The beat-wave accelerator (BWA) scheme is promising for a large acceleration gradient for high energies. Some of the concerns with this accelerator concept are (i) the longitudinal dephasing between the speed of high energy particles and that of plasmons and (ii) the laser pump depletion. The latter problem is analyzed in detail here. To cope with these problems and also to ease some of the requirements on laser and plasma parameters, we propose an accelerator architecture for BWA with the following features: (i) distributed laser staging optically connected by the master oscillator; (ii) optical delay lines synchronizing the timing and phase of each laser stage; (iii) appropriate mirror systems; and (iv) optical guides (plasma fiber) to trap laser beams by acoustic transducers or other mechanism. If necessary, additional collector devices may be added to collect any unused portion of laser power and to convert it for reuse.