Assessment of the deuteron irradiation distribution in the LIPAc High-Power Beam Dump during Commissioning Phase B+

The Linear IFMIF Prototype Accelerator (LIPAc) aims to demonstrate the feasibility of operating a 125 mA deuteron beam up to continuous wave (CW), a key milestone for the development of future fusion-relevant neutron sources such as IFMIF-DONES and A-FNS. In this work, the deuteron irradiation distribution in the High-Power Beam Dump (HPBD) was evaluated during the LIPAc Commissioning Phase B+, when a deuteron beam of approximately 120 mA and 5 MeV (with a maximum pulse duty of 8.75%) was achieved. The irradiation profile was inferred indirectly by comparing neutron flux measurements obtained from activation foils with Monte Carlo radiation transport simulations. Results seem to indicate a more spatially distributed deuteron footprint than previously assumed. Although variations in irradiation distribution can influence thermomechanical stresses in the beam dump, the observed profile leads to a lower maximum power density and is therefore not expected to pose operational concerns. The findings also demonstrate the effectiveness of activation foils as a complementary diagnostic for beam irradiation, providing valuable data for neutron flux characterization and informing safe operation during subsequent LIPAc phases.