Efficient extreme ultraviolet emission from xenon-cluster jet targets at high repetition rate laser illumination

Abstract

We studied extreme ultraviolet (EUV) emission from Xe cluster jet targets irradiated with high repetitive ps and ns laser pulses in the intensity range between 1011 and 1015 W/cm2. It was found that at fixed intensity the conversion efficiency of the laser energy into the EUV emission is higher for ns pulses. In the intensity range used no saturation of the 13.4 nm signal could be reached. At ns pulse duration a conversion efficiency 0.26%@13.4 nm in 2π steradian and 2.2% bandwidth was reached. The laser energy deposition is discussed in relation to the plasma dynamics of the cluster target. We demonstrated that due to the high flow velocity of the cluster jet target an exposition with laser pulses up to 125 kHz repetition rate is possible without any degradation of the EUV emission efficiency. Both the high conversion efficiency and the high repetition rate make this Xe target attractive for an EUV source with high average EUV power.