High yield (⩾108/pulse) DD neutron generator based on a compact, transportable and low energy plasma focus device

Abstract

Abstract A pulsed DD neutron generator based on the plasma focus (PF) device has been developed. The PF device was assembled using a single energy storage capacitor (10 µF) and a triggerable spark gap switch in a compact geometry. The anode of the PF device was made of SS304 material with its tip modified using a high purity tungsten insert. Excluding the power supply, the size of the overall system was 0.6 × 0.6 × 1.0 m and the weight was less than 100 kg. A maximum DD neutron yield of (3.1 ± 0.2) × 108 neutrons/pulse and average DD neutron yield of (2.24 ± 0.16) × 108 neutrons/pulse (pulse duration = 35 ± 4 ns) into 4π sr were observed at a capacitor bank energy of 3.1 kJ (25 kV) and at 4.5 mbar D2 gas filling pressure. The experimentally observed average neutron yield was found to be around 30% more than the estimated yield obtained using scaling laws for neutrons (Y n ≈ 1.7 × 10−10 I 0 3.3; I 0 is the peak discharge current in A). For a peak discharge current of 258 kA at 3.1 kJ, the neutron yield was estimated to be 1.23 × 108 neutrons/pulse. The higher neutron production was attributed to the efficient design of the PF device as well as to the low erosion of the anode tip because of the tungsten insert. Using the time-of-flight method, maximum neutron energy was calculated to be 3.91 ± 0.16 MeV in the radial direction at 4.5 mbar filling pressure. Numerical parametrization using the five-phase Lee model code was performed and found to be similar to PF devices developed across the world.