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, lambda(n), lambda(T), determined from reciprocating Langmuir probe measurements, SOL power flux density e-folding lengths, lambda(q), 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 lambda(n) and lambda(T) are correlated (lambda(T) similar to 1.2 lambda(n)) and both lambda(n) and lambda(T) are on average 2.1-2.5 times larger in IWL configurations than in LSN. In moderate elongation (kappa similar to 1.4) IWL discharges, lambda(q) is largest and agrees with the assumed ITER scaling within the estimated uncertainty (a factor of similar to 2). In IWL discharges lambda(q) measurements are consistent with the expectations of SOL power balance. (C) 2010 Elsevier B.V. All rights reserved.