XUV generation from plasma produced by a XeCl excimer laser on a Cu target

We present a detailed study of XUV and soft X-ray emission from Cu plasma produced by an excimer laser at intensitiesI L≦8·1011 W/cm2. The XeCl excimer laser (ψ≈308 nm) delivers pulses with energyE L≈2.3 J, temporal durationt L≈100 ns and brightnessB≧1014 W/cm2 sr. We recorded a spectral conversion efficiency η=0.5% eV−1 forI L=4·1011W/cm2 in the aluminium window at 73eV with a harder X-ray tail around ≈400eV. We also measured the dependence of X-ray signal on laser intensity and viewing angle. Experimental results have been compared with some analytical laser-plasma interaction models.