Reduction of X-ray laser driver energy.

Abstract Future development of X-ray lasers (XRL) applications goes through a reduction of the driver energy. Amplification close or inside the “water window” using the Li-like recombination scheme was tested. A gain of ∼0.8 cm −1 at 5.77 nm (Ca 17+ ) was measured. On the other hand, at LULI the use of low energy prepulse has permitted to achieve a very efficient saturated X-ray laser working on the 0–1 line (21.2 nm) on the Ne-like collisional scheme. The 5 MW, 200 μm transverse coherence length XRL is extremely well suited for applications.