Ni-like collisional lasers using moderate power laser drivers

The hydrodynamic behavior of a Ta exploding foil using a double pulse in order to achieve favorable conditions for a Ni-like collisional x-ray laser with moderate driver energy have been examined in detail. It is shown that plasma conditions required for high gain lasing can be produced with x4 reduced laser power as compared with Maxon's scheme [Phys. Rev. Lett. 70, 2285 (1993)], provided that the second pulse is correctly timed and is delivered before transparency of the target to the incident laser light. This makes water window x-ray lasers within the reach of many moderately sized laser installations