The correlation of x-ray emission with pinch energy in a 1.5 kJ plasma focus

Abstract

Correlation of x-ray emission with pinch energy from a 1.5 kJ Mather-type plasma focus device for Ag and Sn inserts at the Cu tapered anode tip is reported. The space and time resolved x-ray emission characteristics are investigated by using a simple pinhole camera with appropriate filters and a multichannel pin-diode spectrometer. High voltage probe and Rogowski coil signals are used to estimate the pinch energy. At optimum conditions, the maximum x-ray yield in 4π-geometry is found to be 9 and 8 J/shot with efficiency of 0.6% and 0.5% for Sn and Ag inserted anodes. This is despite the fact that input energy converted to pinch energy is lower at 8% for Sn insert compared with 15% for the Ag insert. An increase in x-ray yield with an increase in pinch energy is observed for Sn as well as Ag. Pinhole images reveal that x-rays of energy less than 5 keV are emitted from the focus region and the high-energy x-rays are emanated from the anode tip.