X- ray emission from laser irradiated clusters

An intense short pulse laser impinged on a cluster imparts large oscillatory velocity v_osc to electrons and heats them. As the cluster expands, electron density falls and at some instant plasma frequency of cluster electrons, omega_p equals omegaradic3 (where omega is the frequency of the laser), giving a resonant enhancement to v_osc. At this instant the electron radiate strong bremstrahlung radiation in the X-ray band. The self focusing of the laser extends the length of the X-ray existing channel, hence the yield of X-ray generation.