Neutronics Assessment of a Compact D-D Neutron Generator as a Neutron Source for the Neutron Calibration in Magnetic Confinement Fusion Devices

Neutronics aspects of a compact D-D neutron generator as a neutron source for the neutron calibration in magnetic confinement fusion devices are assessed by the MCNP calculation. The neutron emission distribution of the compact D-D neutron generator has a large anisotropy not only due to the scattering with the neutron generator body but also due to the intrinsic anisotropy of the differential cross-section of the d(d,n)3He reaction. The angular neutron distribution at the target of the compact D-D neutron generator is calculated with the PHITS code where the slowing down on the accelerated deuterons in the target material is considered. The calibration experiments are simulated by using the MCNP-6 code for the ITER neutron flux monitor (NFM) to be installed in the equatorial port. The detection efficiency of NFM is calculated for a D-D plasma neutron source, an idealistic D-D neutron source, a 252Cf neutron source and the compact neutron generator. It is found that the detection efficiency of NFM for the compact neutron generator is approximately 50% larger than that for the idealistic D-D neutron source. The discrepancy is improved to be 25% by the intention of the target 20cm from the body of the compact neutron generator.