X-ray Intensity Measurements in 2.8 kJ Plasma Focus Device Operated with Argon Using a Five Channel Diode Spectrometer

Abstract

The generation of soft X-rays in a 2.8 kJ plasma focus operated with argon as a filling gas is studied using a system of five pin Si diodes filtered with different thicknesses of Mylar, Aluminium and Copper. Attention is paid to finding the pressure range for highest X-ray emission. The plasma focus device has been supplied by capacitors bank with 25 μF, 20 kV, 200 nH and a closed spark gap, to give a maximum current about 120 kA at working voltage of 15 kV. On this device, some diagnostics were carried out on the plasma focus using ohm voltage divider to record the voltage curves, Rogowskii coil for measuring the current, and five channel diodes to evaluate the temporal evolution of X-rays generated in the device working on argon versus pressure varying between 0.15 and 1.25 mbar. The analysis based on the recorded X-ray signals shows that there are two components in the X-ray emissions: one arising from the focus argon plasma with temperature of 2.5 keV and the other arising from the electron beam activity on copper anode with a temperature of 10 keV. The second component is predominant in most of investigated experiments due to the use of solid anode. In addition to that, the variation of X-ray intensity versus the energy of device was also studied. From the obtained results, it is obvious that the intensity is increased with the energy increasing. The obtained X-ray intensity versus pressure was compared with similar results taken from references and almost similar behavior was observed. The maximum energy of emitted X-rays in 4π geometry is estimated to be about 1.3 J, with an efficiency of 0.046 % at pressure of 0.15 mbar. This PF device is capable to generate X-rays, which was confirmed by making radiography for metallic pieces, electronic elements and other objects.