Assessment of Inner-Wall Recycling in DIII-D Using Tangentially Viewing CID Cameras
Abstract
Using tangentially viewing CID cameras, main-chamber recycling in DIII-D has been experimentally assessed in low-density (n/n_GW ∼ 0.2) L-mode, and low and medium density (n/n_GW ∼ 0.4 vs. n/n_GW ∼ 0.6 ELMy H-mode plasmas. This analysis includes numerical and experimental techniques to estimate the contribution of reflected light from the outer wall region of DIII-D. Poloidally asymmetric Balmer-a emission observed in the diverted configurations was found to be maximum at the region closest to divertor X-points. This result, coupled with UEDGE modeling, implies that the dominant source for core plasma fueling occurs via the divertor region. Measurement of the CII (515 nm) and CIII (465 nm) emission profiles also showed poloidal asymmetry peaking closest to the divertor region. A purely diffusive radial transport model in UEDGE shows that carbon chemically sputtered from the divertor walls is transported into the SOL of the high field side, and subsequently into the core, due to the dominant ion temperature gradient force in the region above the magnetic X-point. Comparisons between UEDGE modeling and experimental trends will be presented.
- Publication:
-
APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- October 2003
- Bibcode:
- 2003APS..DPPGO1013G