DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 338: Carbon migration in the divertor using the C13 method | ||
| Name: | Mathias Groth ( |
Affiliation: | Lawrence Livermore National Laboratory |
| Research Area: | Hydrogenic Retention | Presentation time: | Not requested | Co-Author(s): | S.L. Allens and the Hydrogen Retention, Integrated Modeling, and Boundary Physics groups |
| Description: | Simulate carbon erosion at outer plate as the dominant carbon source and its migration using trace carbon-13; this experiment may be combined with oxygen bake | ||
| Experimental Approach/Plan: | Establish quiescent L-mode plasma, low density as in 2003 with outer strike inboard of the pumping plenum; inject methane C12H4 (or C12D4) at trace level from lower outer plenum into outer divertor common SOL -> establish lowest acceptable injection amount; characterize divertor conditions; repeat methane injection on the following day, but use C13H4; 10+ discharges to inject sufficient amount of C13; remove tiles during vent; this experiment requires to be run on the last day of the campaign!
Alternatively, this experiment could also be exectuted in low-density H-mode, however, ELMs will make interpretation of experimental results more complicated. Also, there will be no direct comparison to 2005 detached H-mode. | ||
| Background: | The 2003 and 2005 C13 experiments were performed in a lower single null configuration with C13H4 injection from the upper outer plenum to simulate carbon erosion being dominant from the main chamber above the midplane. The injected C13 is entrained in the SOL flow toward the inner plate, and deposited at the inner plate (2003 attached L-mode), and the inner plate and private flux region (2005 detached H-mode). The proposed experiment intends to contrast the 2003 results by injecting C13H4 into the outer divertor SOL (common flux region) and measuring the C13 deposition post-mortem. The following questions will be answered: will a dominant outer plate source lead to a similar deposition at the inner plate as seen in the 2003 experiment? What is the dominant mechanism of carbon transport between the outer and inner divertor: the 'long way' via the main SOL versus the 'short way' across the private flux region? | ||
| Resource Requirements: | 2 days of DIII-D operations at the end of the experimental campaign; C13H4 injection from the lower outer plenum; little requirement on heating power if executed in L-mode | ||
| Diagnostic Requirements: | All available SOL diagnostics, including MDS, tangential cameras, RCPs, DTS, fixed Langmuir probes; also CER | ||
| Analysis Requirements: | Analysis of SOL flows from tangential MDS and RCPs (midplane and lower divertor), UEDGE and OEDGE modeling of C13H4 injection and carbon transport | ||
| Other Requirements: | Experiment can be combined with oxygen bake | ||
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