Measurement of Total Energy of Pulsed Electron Beam From a Plasma Focus Device Using Dosimetry of Bremsstrahlung X-Ray

Abstract

In this paper, the total energy of pulsed electron beam from a plasma focus device was studied by measurement of the Bremsstrahlung X-ray dose. The Bremsstrahlung X-ray dose caused by collision of electrons to a copper foil was measured by GR-200A TLD dosimeters. Using the Monte Carlo code, the relationship between the absorbed dose and energy of the colliding electron was determined in the experimental conditions. This relationship is approximately linear and is independent of the electron energy within the energy range of 0–300 keV. The measurements were performed at different charging voltages and different pressures of argon and air as working gases. The mean value of the X-ray dose was higher at experiments with air gas. The maximum X-ray dose of 3.3 mGy, which corresponds to total energy of 48 mJ for electron beam, was measured at 23 kV and 0.9 mbar of air. The total energy of the electron beam at different shots of the same experimental conditions showed large fluctuations around the mean value. This makes it hopelessly difficult to predict the energy of the electron beam in one shot of the plasma focus device. On the other hand, a direct relationship between the energy of the electron pulse and depth of spike on the current signal was observed. The predictability of the energy was significantly improved by increasing the number of shots. The relative standard deviation of the measured energies from the mean value was decreased from 74% for a single shot to 8% for 15 shots, and the mean value of X-ray dose in one shot was significantly increased over the large number of shots.