PERSISTENT SURVEILLANCE FOR PIPELINE PROTECTION AND THREAT INTERDICTION FDF: PWI issues and research opportunities Peter Stangeby University of Toronto Presented at the ReNew Theme III workshop; Taming the Plasma Material Interface UCLA, March 4-6, 2009 UNIVERSITY OF TORONTO Institute for Aerospace Studies Reactors will make their own PFCs to interact with PWI in present devices usually does little to the PFC material. The plasma is essentially still interacting with the material that was installed. In reactors, however, the PWI will strongly work the PFC material, actually creating the wall material that the plasma reacts with. This situation will be so different from what we see today in fusion devices that we have little reliable idea of the consequences. Successful development of fusion power therefore requires that study of PWI on PWI-created PFCs begin as early as possible. This requires facilities that create far more intense PWI than do present devices. Simple estimate of rate at which tokamaks work PFC materials Assume P rad = 75% P heat, thus 0.25P heat = kT s s, where = sheath heat transmission coefficient = 7; T s = plasma average temperature in contact with surfaces = 10 eV assumed here; s = total D/T-ion flux to all surfaces [ions/s], targets and walls. Be, B, C sputtering: physical due to D/T-ions and self-sputtering. Carbon chemical sputtering and RES assumed to be not significant at assumed C surface temperature of 1000C. Y eff (Be/B/C) = 0.021/0.0097/0.005 (Eckstein 2002 yields for maxwellian ions plus a 3kT-sheath). W sputtering is due to (i) self-sputtering, and (ii) sputtering by a low-Z additive required to increase P rad, here 3% C3+ in the target ion flux (~ same effect for N3+). Y eff (W) = The material circulation rate = gross erosion rate = rate at which material is worked is not to be confused with the net erosion rate, which is the required (external) refurbishment rate. Rate at which PFC materials are worked in various devices deviceP heat [MW] annual run time [s/year] fluence of D/T ions to surfaces [TC/yr] * beryllium circulation rate [kg/yr] boron circulation rate [kg/yr] carbon circulation rate [kg/yr] tungsten circulation rate [kg/yr] DIII-D JT 60SA EAST ITER FDF Reactor x ,00039,00023,00035,000 *tera-coulombs = 6.25x10 30 DT-ions Net erosion in the divertor An FDF divertor plasma solution calculated by SOLPS (John Canik): n e ~ m -3, T ~ 10 eV at outer strike point. Ionization mfp of physically sputtered Be, B, C ~ 0.3mm ~ ion larmor radius. Thus probability of prompt local redeposition ~ 1. Thus net erosion