Simulation and Characterization of a Dense Plasma Focus Device

Abstract

Electron temperatures have been measured in a 1 kJ Mather-type dense plasma focus device (UofS-I DPF) with a hollow copper anode at the University of Saskatchewan (UofS) Plasma Physics Lab (PPL). The UofS-I DPF device is powered by a 5 F capacitor bank charged up to 20 kV with an optimum operating pressure of 100 - 200 mTorr argon gas. The features of the plasma dynamics in the UofS-I DPF device have been studied by analyzing signals of the discharge current, the anode voltage, the intensities of electron and ion beams, and the soft x-ray (SXR) and hard x-ray (HXR) radiations. The peak times of signals have been compared with the pinch time. A negatively-biased BPX-65 Si-PIN photodiode array has been used to measure SXR emissions from the UofS-I DPF. The double- lter technique and the ratio method have been used to determine the electron temperature based on the measured SXR intensities. An electron temperature of 5.7 0.7 keV has been obtained for the argon plasma. Moreover, linear correlations of the current dip, the peaks of the electron beam and the SXR and HXR emissions with the peak of the anode voltage have been observed. Linear correlations of the same signals with the electron temperature have also been observed. The Lee model code has been used to determine the optimum capacitor bank voltage and operating pressure for the UofS-I DPF. The Lee code has also been used for tting the experimental current waveform to the computed waveform in order to obtain the mass and current factors. These factors allow the computations of the radial positions and the speeds of the focusing plasma.