Ion cyclotron range of frequency mode conversion physics in Alcator C-Mod: Experimental measurements and modeling

In ion cyclotron range of frequency experiments, we have simultaneously measured the incident fast wave and the mode converted waves in the mode conversion region in D(He3) plasmas using an upgraded phase contrast imaging diagnostic in the Alcator C-Mod tokamak [I. H. Hutchinson, R. Boivin, F. Bombarida et al., Phys. Plasmas 1, 1511 (1994)]. To experimentally validate the full wave TORIC [M. Brambilla, Nucl. Fusion 38, 1805 (1998)] physics kernel, the simulated power deposition and line integrated perturbed density profiles were compared with experimental profiles and are found to be in remarkably good agreement with the experimentally determined profiles. This suggests the physics model and computation algorithm used in TORIC, particularly for the mode converted waves, model the mode conversion physics well. We also report results from initial mode conversion current drive experiments where the modification of the sawtooth period was clearly observed and was shown to depend on antenna phasing suggesting the presence of a localized driven current.