Heat flux width scaling in ITER limiter configurations in support of ITER blanket shield module plasma-facing surface design Proposer: R. A. Pitts (IO), MIT contact: B. LaBombard Motivation ITER first wall blanket shield modules will be shaped to deal with steady state and transient loads and to permit limiter start-up (SU) – ramp down (RD) limiter phases also possible Design is underway but not complete – relying on predicted power folding lengths SU/RD scenarios foreseen on both LFS and HFS Limiter phase up to 5 MA (RU), 7.5 MA (RD)  q||,peak ~40 MWm-2, q,peak as high as 5-6 MWm-2

Heat flux width scaling in ITER limiter configurations in support of ITER blanket shield module plasma-facing surface design Proposer: R. A. Pitts (IO), MIT contact: B. LaBombard JET vs. IPB Motivation New ITER baseline thermal load specifications provide limiter SOL power widths based on L-mode divertor scaling (JET, AUG, JT-60U) modified to account for multiple limiters But L-mode divertor scaling only roughly followed by sparse limiter data which is available (e.g. from JET, 1986) lq|| on HFS SU/RD local (at the limiter) expected to be ~4 x LFS value (ballooning transport and flux expansion) Courtesy of P. C. Stangeby – from original JET expts. reported in S. K. Erents et al., NF 28 (1988) 1209

Heat flux width scaling in ITER limiter configurations in support of ITER blanket shield module plasma-facing surface design Proposer: R. A. Pitts (IO), MIT contact: B. LaBombard Suggested run plan Concentrate on HFS start-up  more like the ITER FW situation (in terms of limiter geometry)  C-Mod LFS limiter structure probably too complex for easy interpretation 1) Make “steady state” SOL profile measurements in limiter plasmas: 2 values of Ip (at ITER relevant q for start-up, e.g. 5-10) For example: Two density plateaux at constant PIN for each Ip Two PIN at constant density for each Ip Note: lq||  R2 Pdiv-0.8q950.5 ne0.9 (IPB L-mode divertor scaling) Use low density (0.2-0.4 nGW) to remain close to expected low ne ITER start-up  build-up SOL scaling database 2) Compare steady limiter folding lengths with same thing in diverted discharges  provide further data for original IPB scaling and compare directly with limiter lengths 3) Maybe try some LFS measurements if possible to see if useful