Exploring X-ray lasing in nitrogen pinch plasma at very high and fast discharge current excitation

Abstract

The possibility to demonstrate X-ray lasing in nitrogen at 13.4 nm through recombination scheme driven by capillary discharge excitation has been explored at a high discharge current of ~95 kA, with ~46 ns quarter period. The emission from nitrogen pinch plasma showed a fast pulse at the instant of pinch formation, overriding the long duration Bremsstrahlung emission. The spectroscopic study revealed dominant X-ray line emissions at 2.8 and 2.1 nm, apart from various X-ray line emissions at higher wavelengths. Line emission at 2.8 nm confirms the formation of NVI charge state of nitrogen. At lower pressures, faint emission of Ly-α line at 2.4 nm indicated formation of NVII ions by further heating. The favourable role of pre-pulse in the formation of higher charge states of nitrogen was also established beyond doubt. This study provides important inputs for future experiments towards demonstration of X-ray lasing at 13.4 nm.