SOL Width Studies for ITER Ramp-up

The present ITER scenarios contain limiter phases in Ohmic or L-mode for ramp-up and ramp-down. Dependencies of scrape-off layer (SOL) density and temperature e-folding lengths on discharge parameters were studied in inner-wall limited (IWL) and lower single null (LSN) discharges on DIII-D in order to benchmark the currently used power flux scaling based on divertor measurements from a number of tokamaks. Scans of the plasma current $(q_{95})$, density, and heating power have been performed. The power flux e-folding lengths derived from the reciprocating probe measurements near the outboard midplane in the IWL configuration are on the average a factor of $\sim 2$ larger than those predicted by the scaling for an outer-wall limited configuration. Probe measurements in LSN configuration were also benchmarked against infrared camera data from the lower divertor.