Carbon Ion Flow Measurements in the DIII-D Divertor and Scrape Off Layer with Comparisons to UEDGE Modeling withFull Drifts

Coherence Imaging Spectroscopy has been used on DIII-D to measure He 1+ and C2+ ion flows; one system views the divertor and a second has a wide angle view of the whole Scrape Off Layer. A tuneable laser provides an unshifted zero velocity reference image which is recorded after each plasma shot. Fourier analysis of the interferogram, followed by tomographic reconstruction, results in images of ion emissivity and flow velocity. Data has been obtained over a wide range of conditions, including divertor detachment. A general feature of the data is that the C2+ flow velocity in the divertor is toward the divertor plate with a velocity in the range of 20-30 km/s, and the sense of the flow flips with the toroidal field, in agreement with UEDGE modelling. Tomographic reconstructions of measured 2D C2+ flow patterns generally show a broader spatial distribution than in the UEDGE modelling with full drifts.