Comparative study of X-ray emission from plasma focus relative to different preionization schemes

摘要

A 2.7-kJ Mather-type plasma focus has been investigated for X-ray emission with preionization produced by an alpha-source, a beta-source, and a shunt resistor. Time-resolved and time integrated measurements are carried out using a PIN-diode-based X-ray spectrometer and pinhole camera. The beta-source (Ni-28(63)) assisted preionization enhances the X-ray emission up to 25%, while preionization induced by depleted uranium (U-92(238)) increases both Cu-K-alpha and total X-ray yield of about 100%. The preionization caused by the optimum shunt resistor enhances the Cu-K-alpha and total X-ray yield of about 53%. It is found that preionization also broadens the working pressure range for the high X-ray yield and improves the shot-to-shot reproducibility of the system. Pinhole images reveal that the X-ray emission from the anode tip is dominant owing to impact of electron bombardment, while the X-ray emission from hot spots is also visible.