Charge-exchange collisions in interpenetrating laser-produced magnesium plasmas

Charge-exchange collisions are one of the effective pumping methods for soft X-ray lasers. Experiments are performed to investigate charge-exchange collisions between highly charged Mg ions in colliding laser-produced magnesium plasmas. Pinhole photography and XUV spectroscopy are used as diagnostic tools. Spectroscopic studies show selective population of n = 3 levels of Mg IX ions, which results in enhancement of respective line intensities. Theoretical calculations also give a large cross section as high as 10−15 cm2 for these charge-exchange collisions when the relative velocities of the colliding ions are of the order of 107 cm s−1. XUV pinhole pictures are taken in early stages, which give more insight into the expansion dynamics of the colliding magnesium plasmas.