Correlation between the neutron yield from a plasma focus device and the jump in the discharge current
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Correlation between the Neutron Yield from a Plasma Focus Device and the Jump in the Discharge Current V. E. Ablesimov, G. V. Karpov, and Z. S. Tsybikov AllRussian Research Institute of Experimental Physics, Russian Federal Nuclear Center, Sarov, Nizhni Novgorod oblast, 607188 Russia Received July 14, 2011; in final form, March 30, 2012
Abstract—The correlation between the neutron yield Y from a plasma focus device and the jump in the dis charge current ΔI has been studied experimentally. The total yield of the DD neutron source was measured by the method of activation of silver isotopes. The time dependences of the neutron and γradiation yields were recorded using scintillation detectors. It is found that, for the given experimental device, the neutron yield depends linearly on the jump in the discharge current ΔI at the instant of neutron generation. The influ ence of the initial deuterium pressure in the discharge chamber on this dependence is examined. DOI: 10.1134/S1063780X12100017
1. INTRODUCTION The linear dependence of the neutron yield Y from the plasma focus (PF) device on the jump in the dis charge current ΔI has already been noticed in [1]. To find out whether such a linear dependence is universal, it is necessary to examine similar dependences in experiments with different designs of the PF chamber. In our experiments, we used a Mathertype dis charge chamber with long cylindrical coaxial elec trodes [2]. The 70mmdiameter anode was used as the powered electrode. The grounded electrode (cath ode) had the shape of a 280mmlong perforated tube with an inner diameter of 120 mm. The cathode and anode ends were positioned in the same plane at a dis tance of 280 mm from the grounded input flange. The anode was separated from the input flange by a ceramic insulator 70 mm in diameter and 70 mm in height. The electrode system was placed in a vacuum chamber sealed with inorganic sealants and pumped out using an oilfree turbomolecular pump. The chamber was arranged at the MODUL [3] and KASKAD [4] facilities with different energy storages. At both facilities, several series of discharges were car ried out at a constant initial deuterium pressure. 2. EXPERIMENTAL SETUP AND PROCESSING OF THE RESULTS The total DD neutron yield was measured by the method of activation of silver isotopes. The time dependences of the neutron and γradiation yields were recorded using scintillation detectors placed in the radial direction at a distance of 3 m from the chamber axis. The discharge current was measured using six identical twoturn inductive coils arranged uniformly at a radius of 65 mm from the chamber axis.
The area of the turn was 30.25 mm2. The calculated sensitivity of the coil was 5.37 × 109 A/(s V). The coil signals were almost identical and proportional to the time derivative of the discharge current. The time dependence of the discharge current was determined by integrating the signal from one of the coils. 2.1. Experimental Results from the MODUL Facility In each shot, we measured the
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