| During normal use of drive-in target neutron tubes,due to energy deposition on the target surface,the temperature of the target surface increases,leading to the desorption of hydrogen isotopes adsorbed in the target,resulting in a decrease in neutron yield.Traditional neutron tubes use titanium targets,but once the target surface temperature exceeds 180 ℃,the adsorbed hydrogen isotopes in the target will Undergo thermal decompostion.Therefore,it is necessary to study new high-temperature resistant neutron tube target materials,in order to provide a reference basis for the use of neutron tubes at high temperatures.This article mainly adopts a combination of simulation and experimental methods to study the technology of self formed magnesium target neutron tubes.The research content and results are as follows.Firstly,simulation calculations and experimental comparisons were conducted on the neutron yields of magnesium and titanium targets based on numerical simulation software and SRIM.Through SRIM simulation of the range and energy loss of incident deuterium ions,as well as discrete integration of the D-D reaction cross-section/D-T reaction cross-section in the low energy range(60 ke V～120 ke V)using numerical simulation software,the theoretical neutron yield of magnesium targets is about 50% higher than that of titanium targets.Subsequently,research was conducted on the deuterium saturation effect of magnesium and titanium targets,and deuterium ion implantation experiments were conducted on magnesium and titanium targets at low temperatures.The beam intensity is 200 μA,The titanium target reaches saturation around 400 minutes,with a beam intensity of 100 μA The magnesium target still reached saturation within 600 minutes.By extrapolating the neutron yield curve of the magnesium target over time,it was found that the saturation time of magnesium is up to 100 hours,but the neutron yield of the magnesium target is still higher than that of the titanium target at unit beam intensity per second.Theoretical calculations were conducted using the theoretical deuterium content of magnesium targets and the deuterium ion implantation rate,resulting in a beam intensity of 100 μA at room temperature,The theoretical saturation time of magnesium target is up to 100 hours,which is consistent with the experimental results.A simulation study was conducted to investigate the effects of different temperatures,beam parameters,and target types on the deuterium content in magnesium targets due to long-term unsaturation.By using the temperature dependent curve of the amount of deuterium released from magnesium targets,the beam intensity corresponding to the amount of deuterium released and the thermal equilibrium temperature were obtained.This article designs a magnesium alloy target and a magnesium film copper bottom target,and uses COMSOL to study the temperature of the magnesium alloy target surface and the temperature of the magnesium film target surface as a function of beam parameters(incident particle energy,beam intensity,beam spot radius).It is found that the temperature of the magnesium alloy target surface is lower.On the premise that the target surface does not exceed the thermal analysis equilibrium temperature,the magnesium alloy target has been optimized and designed,resulting in an increase in target beam power from34 W to 60 W.Subsequently,experiments were conducted to verify the results,This experiment controls the target surface temperature by moving the position of the cooling water pipeline and adjusting the beam intensity.In addition,thermocouple temperature measurement and multi physical field coupled heat transfer simulation are used to calibrate the measurement of target surface temperature.Through experimental research on the time-dependent neutron yield curve of magnesium alloy targets at different temperatures,the deuterium release performance of magnesium alloy targets was studied.It was found that when the target surface temperature of magnesium alloy targets exceeded the thermal analysis equilibrium temperature,the neutron yield in the target would significantly decrease.And a comparative study was conducted on the neutron yield of magnesium alloy targets and magnesium film targets at the same temperature.It was found that the deuterium content of both magnesium alloy targets and magnesium film targets gradually decreased with increasing temperature,but the neutron yield of magnesium alloy targets was always higher than that of magnesium film targets.Finally,it is concluded that the integrated design of magnesium alloy targets and their high temperature resistance have advantages in neutron tube applications. |
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