Development and applications of 10-mJ x-ray lasers at PALS

Abstract

We give an overview of recent advances in development and applications of deeply saturated Ne like zinc soft X-ray laser at PALS, providing strongly saturated emission at 21.2 nm. Population inversion is produced in the regime of long scale-length density plasma, which is achieved by a very large time separation between the prepulse (<10 J) and the main pump pulse (~500 J), of up to 50 ns. This pumping regime is unique in the context of current x-ray laser research. An extremely bright and narrowly collimated double-pass x-ray laser beam is obtained, providing ~10 mJ pulses and ~100 MW of peak power, which is the most powerful soft X-ray laser yet demonstrated. The programme of applications recently undertaken includes precision measurements of the soft X-ray opacity of laser irradiated metals relevant to stellar astrophysics, soft X-ray interferometric probing of optical materials for laser damage studies, soft X-ray material ablation relevant to microfabrication technologies, and pilot radiobiology studies of DNA damage in the soft X-ray region. A concomitant topic is focusing the x-ray laser beam down to a narrow spot, with the final goal of achieving ~10¹³ Wcm^-2.