Development, design, and testing of a microwave-driven compact rotating-target D-D fast neutron generator for imaging applications

Abstract

A compact D-D fast neutron generator system was developed with an emphasis on imaging applications. It is equipped with an electron cyclotron resonance microwave ion source, an electric field method electron suppression electrode, and a rotating beam target. The design, mechanical assembling, and initial performance of the system is presented in this work. Electrostatics and charged particle tracing simulations were employed to dimension components in the vacuum system and estimate the size of the ion beam spot on the target surface. Stable operation of the neutron generator was possible with accelerating potentials of up to −120 kV and an estimated averaged ion beam current of around 0.5 mA. At these conditions, the neutron yield was estimated to 6 ⋅ 107 s−1 based on a combination of detailed Monte Carlo MCNP6 models and the ambient dose rate reading of an LB6411 neutron probe. The neutron emitting spot size was compared to the ion beam spot size and experimentally determined with an attenuating edge technique to be between 1.7 and 2.6 mm. With these neutron yield and emitting spot size values, the system compares favorably with commercially available neutron generators, and this context is also presented.