Angular distribution of ion beams energy and flux in a plasma focus device operated with argon gas

Abstract

Energy and flux of ion beams in a Mather type (5 kJ) plasma focus device was investigated. The experiments were performed with argon as the chamber gas at the optimum pressure of 0.3 mbar and the charging voltage of 15 kV. Six identical Faraday cups located at angular positions 0, 15, 30, 45, 60 and 75° with respect to the anode axis were exploited to collect ion signals. The Faraday cups were mounted on a quadrant holder so that all Faraday cups have the same radial distance of 7 cm from the anode tip. In order to gain knowledge of target ions, when the plasma focus device is used for thin film deposition, three different targets of copper, graphite and tungsten were inserted on top of the anode tip. The ion signals registered by Faraday cups showed three main peaks relating to X-ray, argon gas and target ions, respectively. Plots of ion flux as a function of ions energy were obtained for argon gas and different targets separately. Energy spectra obtained from the Faraday cups revealed different anisotropies for argon gas and targets ions.