Beatwave acceleration experiments at UCLA

The possibility of using high-density plasmas as a medium for a high-gradient accelerator is being studied experimentally at UCLA. This proof-of-principle experiment uses a large CO₂ laser to excite plasma waves with large accelerating fields and a 1.5-MeV linac to probe the fields. Preliminary results from optical scattering diagnostics indicate that the length L of the wave times the accelerating gradient E_a is so far limited to E _a⩽3.2 MeV whereas the experiment is designed to achieve E_aL≈25 MeV. In addition, particle calculations indicate that the collection efficiency needs to be >2% to begin to see single electrons. With the help of electron-optics codes, the authors are beginning to optimize the collection efficiency for 5-MeV electrons