Research On The Effect Of Target Film Material And Its Surface Layer On The Yield And Target Lifetime Of D-T Neutron Tube

The neutron tube is a small accelerator neutron source.The ion source,acceleration system,target,and air pressure regulation system are sealed in a ceramic tube to form a compact electric vacuum device.It is an important neutron source for neutron physics and neutron application technology research.It is widely used in neutron well logging,explosives and drug detection,irradiation breeding,neutron photography,online neutron activation analysis and other fields.For different application studies,it is necessary to obtain neutron tubes with high neutron yield and long lifetime.The target characteristic is one of the important parameters of the neutron tube.The neutron tube target is composed of the target film and the target substrate.The target film is used to store helium gas inside the neutron tube.It is also the interface where the D-T reaction.The production process,materials,thickness and other factors of the film directly determine the neutron tube yield and target lifetime.Titanium is the elemental metal with the highest hydrogen absorption density discovered so far,and is often used as a neutron tube target film material.However,elemental titanium has inherent defects as a neutron tube film material.For example,titanium metal has poor sputtering resistance.After hydrogen absorption,the plasticity,flexibility and tensile strength are greatly reduced,leading to occur the hydrogen embrittlement,and even a large number of cracks are generated in the body.In view of the defects of elemental metal target materials,we doped other metal into the titanium target film material to form alloy target materials to improve the mechanical properties of elemental metals.In addition to the target film material will affect the neutron tube neutron yield and target lifetime,in the neutron tube target transport and storage process,the surface of the target film is easy to form an oxide layer,which will also affect the neutron yield and target lifetime.After the impurity ions bombarding the target,the helium gas is displaced and the target is damaged,which also reduces the neutron yield and lifetime.The main work of this paper firstly uses SRIM software to simulate the neutron yield of the pure titanium target which the target film with an oxide layer,and compares it with the neutron yield measured by ~3He neutron monitor.The simulation results are in good agreement with the experimental results.It proves the reliability of SRIM software simulation calculation,which can be used to develop related materials and predict performance.Then change the incident ion energy,oxide thickness,protective overcoat material,alloy target material and alloy ratio,and study the influence of the above conditions on neutron tube neutron yield and target lifetime using SRIM simulation software.The results show that the alloy target material can improve the sputtering resistance of the target,and the protective layer on the target film can further improve the target lifetime,and can prevent the formation of oxide layer on the target surface,further obtaining high neutron yield.Finally,after analyzing a large amount of simulation data,the optimal target design scheme for high yield and long target lifetime of neutron tubes is obtained.