Computer Modeling of Capillary Pinching Discharge for the Purpose of XUV Radiation Source Design

Fast capillary discharge in nitrogen is studied as a source of incoherent monochromatic radiation in “water window” wavelength range. Namely, the generation of spectral line with the wavelength of 2.88 nm, corresponding to the quantum transition 1s2p → 1s² of heliumlike nitrogen ions, is studied. Radial-time dependences of selected plasma quantities and of specified line emitted intensity, corresponding to our experimental setup with a 3.2-mm capillary diameter, discharge current pulse amplitude of 13.5 kA, and a 72-ns quarter period, are presented for various initial pressures of nitrogen. The evaluated peak value of the line intensity has been found at about 50 Pa and has been proved by the laboratory experiment.