Experimental Investigations of x-ray Emission in a New Filippov-Type Plasma Focus

Abstract

We present an experimental study of the soft and hard x-ray performance characteristics of neon and neon-krypton mixture (Pkr up to 0.2 torr) plasma produced by a new Filippov-type plasma focus device named “Dena”, with 90 kJ (25 kV, 288 µF) operating at pressures in the range 0.3–1.5 torr. In this investigation, the soft and hard x-ray intensities are measured using a filtered PIN diode, a pinhole camera with a Be filter (10 µm thickness), a plastic and NaI scintillators. Using pure neon as the filling gas, and a charging voltage of 16 kV with 37 kJ stored energy, the maximum intensities of the soft and hard x-rays were found to be about 5 V/shot and 2.2 V/shot, respectively. These measurements were obtained at an optimum operating pressure in the range of 0.5–0.9 torr (for the soft x-ray) and about 0.8 torr (for the hard x-ray). The relationships between the optimum neon pressure range and the time of spike appearances on the discharge current signal were experimentally studied. The results indicate that, the x-ray emission is more sensitive to the time of spike appearances than the neon filling gas pressure. By using a krypton admixture to the neon filling gas (PNe = 1 torr), the most pronounced effect is observed for the hard x-ray yield (up to eight times of the initial value) at the optimum krypton pressure of about 0.1 torr. The measurements of maximum x-ray intensity, performed with krypton admixture, show that as the pressure of krypton admixture increases, the optimum discharge voltages fall to a value depending on the quantity of krypton admixtures used. This effect was generally an intensity decreasing matter for the soft x-ray.