Estimate of convective radial transport due to SOL turbulence as measured by GPI in Alcator C-Mod

The convective radial transport effects of SOL turbulence have been estimated using recent turbulence data from the gas puff imaging (GPI) camera diagnostic on Alcator C-Mod. The average radial turbulence speed within the region 1-2 cm outside the separatrix near the outer was calculated by a 2-0 cross-correlation technique to be V-t similar to 0.2-0.3 km/s. Assuming this to be the local convective plasma velocity, the density SOL width lambda(n) was evaluated using a simple convective model to be lambda(n) similar to 4-7 cm, which is similar to 2-3 times higher than that measured using a Langmuir probe. This convective velocity was also similar to 2-3 times lower than the velocities estimated from analytic blob models, but showed a similar scaling with plasma current at constant q(95). The measured blob speeds were lower than both the convective speeds and the analytic blob model speeds.