Numerical Optimization of Neon Soft X-ray Emission in a Spherical Plasma Focus Device with Lee Code

A comprehensive numerical investigation was performed to optimize neon (Ne) soft X-ray emission (Ysxr) from a spherical plasma focus (SPF) device using the latest Lee code. As a prerequisite for predictive modeling, the code was benchmarked against the experimentally measured discharge current waveform of the 135 kJ SPF [1]. In this numerical study using the Lee code (RADPF5.16FIB), the computed current trace is first fitted to the measured one at 14.3 Torr deuterium (D2) gas and the obtained best-fitted values of the model parameters are found as . These values were then adopted in a systematic optimisation study of the pinch-plasma conditions. The simulations covered Ne fill pressures from 0.5 to 7 Torr, anode and cathode radii at fixed ratios of and , and charging voltages from 15 to 30 kV. In all the cases, the plasma pinch temperature was constrained to the characteristic neon emission window of 2.3 × 106 – 5 × 106 K (≈ 200–500 eV). For each electrode geometry the Lee code identified a unique combination of fill pressure and charging voltage that maximized Ysxr. At moderate electrode sizes and bank voltages of 25 kV the SPF is predicted to deliver peak Ne soft X-ray (SXR) yields exceeding 5 kJ per shot with efficiencies greater than 4%. These findings demonstrate that the Lee model code, when calibrated to measured current traces, provides a robust and quantitative tool for the design and scaling of compact, high-performance Ne SXR sources.