Sensitivity of fast ion losses to magnetic perturbations in the European DEMO

Abstract The limits for the heat loads on the DEMO first wall are significantly stricter compared to those of ITER due to cooling and breeding blanket requirements. Fast particles in the form of NBI ions can escape the confinement due to magnetic perturbations and produce a significant power load on the first wall. In this contribution, we use the fast ion orbit-following code ASCOT to study NBI losses under the effects of 3D magnetic perturbations, including toroidal field ripple and ferritic inserts. The losses were found to not endanger the integrity of the wall, with loads remaining below 40 kW/m 2 even with unmitigated ripple, and losses did not increase above 2.5 % even with 16 toroidal field coils. Ionization in the scrape-off layer was not found to increase the losses significantly for realistic density profiles, and the design of the wall allows for some flexibility in the distance between the plasma and the first wall tiles.