Research on Multifunctional Rotating Target Device

Abstract

This paper focuses on the main problems of unstable neutron yield and continuous decrease in neutron yield when using static water-cooled target in the D-D neutron generator. A multifunctional compact rotating target device was developed, which adopted an integrated design and was compact in structure and small in size, equipped with functions such as high-speed rotation and water-cooled of target body, visual monitoring of target point, real-time measurement of target surface temperature, and real-time monitoring of neutron yield. This paper introduced the performance parameters of several major high current neutron generators rotating targets in the world, and elaborated on the advantages of rotating targets compared to traditional static targets. The main structure and functional design of the device were introduced. The main structure of the target was composed of a vacuum target chamber, target plates, beam pipes, circulating cooling water pipes, accompanying particle pipes, target monitoring pipes, stepper motors, and corresponding seals. The functions and structural components of each device were elaborated in detail. In order to study the influence of the structure of the rotating target device on neutron scattering, the energy spectrum distribution of source neutron at various angles in space was simulated by using TARGET software. The energy spectrum data was input into the MCNP data card, and 40 point detectors were set up, with 0°-360° distributed at a distance of 1 m from the target surface. The influence of target structure on neutron scattering was calculated using MCNP simulation. The result of simulation data shows that the target structure broadens the neutron spectrum peak by 0-0.057 7 MeV, and the relative angular yield of scattered neutrons at various angles accounts for 10.53%-26.75%. The influencing factors of neutron scattering effects at several key angles based on energy spectrum curves were analyzed. The vacuum degree, target surface temperature load, and neutron yield stability of the rotating target device were tested. First of all, the average energy of a 300 keV deuterium particle beam in a target thickness of 1 mg/cm2 deuterium titanium target was theoretically calculated. The source neutron flux was calculated using the average energy, and then the device was installed on a neutron generator at Chinese Institute of Atomic Energy to conduct preliminary tests on various performance. The test results show that the vacuum degree of the rotating target remains stable at around 3×10−5 Pa for a long time. Compared with static targets, rotating target improves neutron yield stability by one order of magnitude, and the maximum temperature of the target decreases by 13 ℃. And the cooling effect of the rotating target device was analyzed under different rotational speeds. The results show that as the rotational speed increases, the cooling effect gradually improves. Therefore, the rotating target device designed in this paper basically achieves the expected function, effectively solving the problem of continuous decrease in neutron yield, and the functional test results are normal with low neutron scattering effect. Finally, this paper also analyzes the problems in the simulation calculation results and measurement results, and proposes improvement and optimization plans.

Keywords

• multifunctional compact rotating target
• neutron angular distribution
• neutron scattering
• accompanying particle measurement