SOL width in limited versus diverted discharges in DIII-D

An experiment aimed at benchmarking the ITER scrape-off layer (SOL) power width scaling in limited L-mode discharges has been conducted on DIII-D. Scans of the main scaling parameters were performed in an inner-wall-limited (IWL) magnetic configuration. Using the near-SOL density and temperature e-folding lengths, λn, λT, determined from reciprocating Langmuir probe measurements, SOL power flux density e-folding lengths, λq, are derived. A few lower single null (LSN) discharges were also run for comparison. The results are generally in agreement with the ITER design assumptions, finding that λn and λT are correlated (λT∼1.2λn) and both λn and λT are on average 2.1-2.5 times larger in IWL configurations than in LSN. In moderate elongation (κ ∼ 1.4) IWL discharges, λq is largest and agrees with the assumed ITER scaling within the estimated uncertainty (a factor of ∼2). In IWL discharges λq measurements are consistent with the expectations of SOL power balance.