An optimized microchannel Ta target for high-current accelerator-driven neutron sources

An optimized neutron producing tantalum target with an optimized internal microchannel cooling was developed for a 70 MeV proton beam with a peak current of 100 mA, a duty cycle of 1.43% and an average power of 100 kW on a target surface area of 100 cm 2. In this work a target with microchannel cooling structure is described which matches with the proton’s energy to minimize hydrogen implantation and to produce energy deposition with optimum homogeneity inside the target to minimize the thermal stresses. For the purpose of getting an optimal target design, the investigations of energy deposition, proton fluence, the spatial distribution of (p, n) reactions and the spatial distribution of stopping protons of the target with different microchannel geometries were performed with the particle transport code FLUKA. The resulting design produces a homogeneous proton fluence and energy deposition without hot spots. Furthermore, only 4.4% of the impinging protons accumulate in the metal target, which significantly decreases the risk of hydrogen embrittlement and blistering.