Integrated Simulations of Target Erosion and Impurity Transport on <scp>EXL</scp> ‐ <scp>50U</scp> With <scp>ITCD</scp> and <scp>EMC3</scp> ‐ <scp>EIRENE</scp>

ABSTRACT The EXL‐50U spherical torus has been proposed as a platform for validating the physics and engineering solutions associated with proton‐boron‐11 (p‐ 11 B) fusion. However, B ions, due to their high charge state and substantial mass, can cause significant erosion of divertor targets. In this work, an integrated framework composed of the ITCD and EMC3‐EIRENE codes is employed to conduct a predictive study of target erosion and subsequent impurity transport in the EXL‐50U device. The background plasma and B impurity information, including plasma density, temperature, and particle flux, are simulated with the EMC3‐EIRENE code. It is shown that B impurities have a stronger sputtering capability than hydrogen (H). Though the particle flux of B ions is much lower than that of H, the larger sputtering yield of B ions causes the erosion levels to be even higher than those of H. Based on this, the erosion/deposition dynamics of C impurities and the transport of eroded C particles are studied by the ITCD code. The simulation results indicate that B particles deposited on the C substrate offer only limited protective effects, meaning the C target primarily remains in an erosion‐dominated regime in EXL‐50U.