Numerical Study for Prediction of Neon Soft X-Ray Yield Emitted from the Plasma Focus Devices Using the Lee Model Code for Different Anode Shapes

Abstract

Numerical experiments were performed using the Lee model code to study the soft X-ray characteristics versus pressure at different operating voltages of the NX2 plasma focus device for two types of anodes (cylindrical and tapered). It was observed that the computed yield increased by 5 times when switching from the cylindrical anode to the tapered one, which agreed with the experimental results. Later, numerical experiments were conducted to study the effect of the different tapering conditions (anode radius at the end of the taper and axial distance at the start of the taper) on the soft X-ray yield, interesting results were reached. We found that the yield is not related to the axial distance for the taper start, but is largely related to the end anode radius of the taper, as there is an optimum end anode radius of the taper that gives the highest yield for soft X-ray. The convergence in previous computed and measured results was taken advantage to conduct numerical experiments on the PF-24 device to find the soft X-ray characteristics and the maximum soft X-ray yield corresponding to the optimum pressure for different anode shapes (cylindrical and tapered). In addition, numerical experiments were conducted to find the optimum conditions of geometric dimensions of the cylindrical anode (anode radius, anode length), and tapering conditions (anode radius at the end of the taper and axial distance at the start of the taper) which give the maximum soft X-ray yield for PF-24 device. The results obtained for the PF-24 device behave identically to the behavior of the results obtained for the NX2 device.