Scaling Laws of Nitrogen Soft X-ray Yields from 1 to 200 kJ Plasma Focus

Abstract

Numerical experiments are carried out systematically to determine the nitrogen soft X-ray yield for optimized nitrogen plasma focus with storage energy E0 from 1 to 200 kJ. Scaling laws on nitrogen soft X-ray yield, in terms of storage energies E0, peak discharge current Ipeak and focus pinch current Ipinch were found. It was found that the nitrogen X-ray yields scales on average with \( {\text{Y}}_{\text{sxr,N}} = 1.93 \times {\text{E}}_{0}^{1.21} {\text{J}} \) (E0 in kJ) with the scaling showing gradual deterioration as E0 rises over the range. A more robust scaling is \( {\text{Y}}_{\text{sxr}} = 8 \times 10^{ - 8} {\text{I}}_{\text{pinch}}^{3.38} \). The optimum nitrogen soft X-ray yield emitted from plasma focus is found to be about 1 kJ for storage energy of 200 kJ. This indicates that nitrogen plasma focus is a good water-window soft X-ray source when properly designed.