Physical Design And Experimental Test Of Miniaturized D-D Neutron Generator Based On Inertial Electrostatic Confinement

The miniaturized controlled neutron source can be widely used in the development of neutron application technology systems such as neutron activation analysis,neutron photography,nuclear fuel detection,etc.It has important application value.Currently,the miniaturized controllable neutron sources that have been realized mainly include sealed neutron tube and compact neutron generator,etc.The sealed neutron tube has a low neutron yield and a short service life.The main problem of compact neutron generator is that the cost is still too high,so it is not widely used and applied.This study intends to develop a miniaturized D-D neutron generator based on inertial electrostatic confinement(IEC).Compared with the compact neutron generator,it is characterized by relatively simple structure,smaller size and lower cost.The overall design scheme of IEC miniaturized D-D neutron generator was proposed.The electric field distribution in the discharge cavity of IEC miniaturized D-D neutron generator was simulated by using COMSOL Multiphysics software.The results showed that the maximum electric field intensity appeared near the outside of the grid cathode column.At-100 k V grid cathode,the maximum electric field intensity can reach 10~7 V/m.The electric field intensity between anode and cathode can be maintained at 10~6 V/m.The optimization parameters determined by simulation are as follows:the pole spacing between the grid anode and the grid cathode is 31 mm,the number of cathode columns is 8,and the number of anode columns is 24.Plasma distribution in discharge cavity of IEC miniaturized D-D neutron generator was simulated by COMSOL Multiphysics.The results show that the area with high density of argon ions is concentrated in the inner edge of the grid cathode,and there are several regular high density argon ion bands between the anode and cathode.Under the pressure range of 3-6 Pa in the cavity and the same grid cathode high pressure,the discharge current increases and the argon ion density increases with the increase of the pressure.At 3 Pa pressure in the cavity,the discharge current increases with the increase of the high voltage of the grid cathode,and so does the density of argon ion.The geometric model of IEC miniaturized D-D neutron generator,the sampling theoretical model of glow discharge D~+ion energy,initial position,incident direction and D-D nuclear reaction position are constructed by Monte Carlo program Geant4under the condition of deuterium-filled gas.The transport and collision process of D~+ions produced by glow discharge in cavity are simulated.The neutron energy spectrum and neutron Angle yield distribution of IEC miniaturized D-D neutron generator are simulated.The results show that the energy of the generated D-D neutrons is mainly distributed in the range of 2.2Me V to 2.8Me V,and the energy spectrum widening is large.The slowing down and scattering effect of the neutron generator structure materials will further widen the energy spectrum of the incoming neutrons,and lead to the generation of lower energy neutrons.The simulation results of angular yield distribution show that the neutron differential yield is lower in the small Angle of 0°to40°and the large Angle of 140°to 180°,while the neutron differential yield is higher and more evenly distributed in the 40°to 140°region.On the basis of the fabrication and installation of the prototype,the preliminary test of IEC miniaturized D-D neutron generator is carried out.Under the condition of using-10 k V/10 m A high voltage power supply and filling with deuterium gas,the glow discharge in cavity is realized.The preliminary test results show that in the range of 10-30 Pa in the cavity,the discharge voltage rises rapidly with the decrease of the pressure,and the neutron dose rate monitored by the rem meter also increases significantly.It indicates that the glow discharge of deuterium gas can lead to the generation of neutrons in D-D fusion reaction,and the high discharge voltage is conducive to the improvement of neutron yield.In addition,the observed glow discharge appears as pulse mode,which is mainly due to the low maximum load current of the high voltage power supply.Therefore,in the next step,high voltage power supply with higher voltage and load current should be used to carry out detailed experimental research.