Simulation of W diaphragm efficiency for mitigation of RE beam in ITER

Simulation of the mitigation efficiency of the RE beam impact on the ITER first wall by special sacrificial W diaphragm has been performed using ENDEP, MEMOS and TOKES codes. According to the technique proposed, the RE beam should deposit its energy onto the special sacrificial diaphragm consisting of separate tungsten 'nails'. The 'nails' is partly evaporated and then the beam power deposited into the vaporized and ionized W plasma shield. The wall heat load mitigation is due to the RE beam energy deposition into the W plasma and its re-radiation onto larger wall area. Calculated tolerable beam energy should not exceed 90 MJ to ensure absence of melting for 10 ms RE beam deposition.