Optimized plasma high harmonics generation from ultra-intense laser   pulses
  Plasma high harmonics generation from an extremely intense short-pulse laser is explored by including the effects of ion motion, electron-ion collisions and radiation reaction force in the plasma dynamics. The laser radiation pressure induces plasma ion motion through the hole-boring effect resulting into the frequency shifting and widening of the harmonic spectra. Classical radiation reaction force slightly mitigates the frequency broadening caused by the ion motion. Based on the results and physical considerations, parameter maps highlighting optimum regions for generating a single intense attosecond pulse and coherent XUV radiations are presented. 
Suo Tang, Naveen Kumar, and Christoph H. Keitel
physics.plasm-ph