A design and experimental investigation of thermal characterization of a high-power lithium target under proton-beam-equivalent loading for accelerator-based boron neutron capture therapy (BNCT)

In this study, the thermal management of a high-power lithium target utilized in accelerator-based boron neutron capture therapy (BNCT) is systematically investigated through numerical simulations and experimental validation. A modular-designed thermal experimental platform is developed, capable of operating under a wide range of flow rates, temperatures, and cooling capacities, ensuring precise control and repeatability for high-power target characterization. A 15.8 kW prototype target with a unit heat flux density of 1.58 MW/m² is constructed, employing microchannel-cooled copper substrates and electric heating rods to simulate proton beam heat deposition; the beam effect is represented by a beam-equivalent thermal load. Three microchannel configurations were evaluated using Computational Fluid Dynamics (CFD) models coupled with the SST k-ω turbulence model, validated against experimental data for Reynolds numbers spanning 560–18,700. The optimized 1 mm microchannel design demonstrated superior thermal performance, achieving 93.2% heat removal efficiency at 3.6 m/s coolant velocity while maintaining 28% lower pressure drop compared to conventional designs. Transient analysis of pulsed proton beam operation revealed attenuated temperature fluctuations in the lithium layer, attributable to efficient substrate cooling and thermal buffering by the anti-blistering layer. The numerical model is established in accordance with the thermal mock-up configuration, and the experimental measurements show good agreement with the CFD predictions, confirming the reliability of the proposed thermal management strategy. These findings establish a validated framework for thermal characterization of high-power BNCT targets, providing essential design guidelines and operational insights for managing extreme thermal loads in next generation neutron sources.