Design of magnetic circuit and extraction system of ECR ion source for intense neutron tube

Abstract

The magnetic circuit and extraction system were optimized to improve the utilization of neutral gas and neutron yield of a sealed intense neutron tube. An experimental system was established to study the relationship between microwave absorption efficiency and the magnetic field strength. The microwave absorption efficiency can reach 100% when the magnetic field intensity at the microwave window is 0.095 T. To further improve the distribution of ECR region, CST was used to simulate the internal magnetic field distribution of the ion source. The radial and axial magnetization results with the single and double magnetic rings were obtained by changing the position and spacing of the magnetic rings. There are three ECR regions and the location of ECR zones is suitable, when the distance between the center of the magnetic ring and the origin of the resonator is 12.5 mm and the distance between the centers of the two magnetic rings is 60 mm. A two-electrode slit extraction system was designed for uniform beam distribution on target. Compared with the original extraction system, the maximum current density is reduced by 82.5% and the target utilization area is increased by 38.54%, which will effectively reduce the thermal load of the target.