Shock waves and ionizing radiation plasmas produced by a mode-locked laser

Abstract

The expansion of plasmas produced by a mode-locked Nd:glass laser has been studied. With help of the second harmonic radiation of the laser itself the shock waves in the initial stages after breakdown are recorded. With a streak camera the time development of the plasma depending on the gas pressure and the focal length of the focusing lens was studied in He, Ar, Kr, Xe, N₂, CO₂ and SF₆. While the shock waves obey the well known relations for ideal shock waves, the stepwise plasma expansion towards the lens can be described by a simple ionization model.