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

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.

Development of a portable pulsed fast ⩾106 neutron generator based on a flexible miniature plasma focus tube

“…The observed variation in neutron yield with filling pressure could possibly be due to the variation in the plasma/current sheath speed (v s ) in the axial acceleration phase, which varies as the inverse square root of the filling gas pressure (v s ∝ I 0 /ap 1/2 ; a: anode radius). Other possible reasons for neutron yield variation with D 2 gas filling pressure have been explained in detail elsewhere [43]. Nevertheless, more than 30% variation in neutron yield under the same operating conditions was observed, which could be due to poor shot-to-shot reproducibility of the plasma focus discharges.…”

“…The current-derivative waveform was observed to be of a simple underdamped L-C-R discharge, and its time-period was measured to be 14.3 µs. Using the short-circuit discharge current time-period (T 0 ), the inductance and the maximum peak discharge current were calculated using formulas described elsewhere [43]. The value of the inductance was calculated to be 215 nH.…”

“…The peak-to-peak separation between the first and second pulse was found to change with the change in PSD position, which could be associated with the change in the flight time of the neutrons. The time-of-flight separation between the hard xrays and neutron pulse was used for the calculation of neutron energy, as described elsewhere [43]. The neutron energy along the axis was calculated to be (2.49 ± 0.23) MeV, whereas the same perpendicular to axis (radial) was calculated to be (2.03 ± 0.12) MeV.…”

Transmutation of Palladium at Electrochemical Interfaces: Experimental and Theoretical Validation with Second Order Perturbation Theory

“…particular, boron neutron capture therapy (BNCT), is tremendous. 1 However, neutron sources are not easily accessible as they are expensive and require complex operating procedures.…”