Design of a D-D Neutron Source Based on Permanent Magnet Microwave Ion Source and Titanium Drive-in Target

A compact deuterium-deuterium（D-D） neutron source system with a designed neutron yield of 1×10⁹ s⁻¹ based on permanent magnet microwave ion source and titanium（Ti） drive-in target technique is described. This neutron source system has been tested for more than 800 hours, and it can operate repeatedly and stably at present. The early test results show that the system has high ignition frequency and low neutron yield. And the D plasma cannot discharge after long time operation due to the Al₂O₃ ceramic window which used for the microwave feed being ablated by the emitted secondary electrons. The damage of Al₂O₃ ceramic window was effectively inhibited by adding a BN protection plate in the plasma chamber and an electron suppression resistance between the Ti target and the high voltage electrode in the vacuum chamber of the neutron source system. By optimizing the structure of the plasma electrode and increasing the vacuum degree, the ignition frequency of the system is reduced, and the neutron yield is increased. The neutron yield is up to 2.0×10⁸ s⁻¹ during the 5 mA and 70 keV D ions bombarding the Ti target. When the deuterium ion energy is 97 keV and the D beam intensity is 6.6 mA, the neutron yield of the system reaches 5.2×10⁸ s⁻¹.