DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 448: Sensitivity of ELMs and Particle Control to Triangularity | ||
| Name: | C. Craig Petty ( |
Affiliation: | General Atomics |
| Research Area: | ITER Demonstration Discharges | Presentation time: | Not requested | Co-Author(s): | -- |
| Description: | Determine how close the designed ITER triangularity is to the ELM-free "cliff" for the baseline "Scenario 2" at beta_N=1.8. Will the ELM frequency be increased, and the divertor cryopumping improved, by small changes away from the standard ITER plasma shape? In the future, this could be expanded to the effect of plasma shape on RMP ELM-suppression. | ||
| Experimental Approach/Plan: | (1) Faithfully reproduce the ITER plasma shape and establish the baseline "Scenario 2" at beta_N=1.8 and q95~3. (2) With the lower divertor cryopump cold, scan the lower triangularity up and down either vary slowly or shot-to-shot. (3) Repeat triangularity scan, but this time use the density control from the I-coil (n=3 RMP) to maintain a constant, low density during the scan. (4) Repeat the triangularity scan, but this time warm up the lower divertor cryopump and do not use I-coil density control. | ||
| Background: | For the ITER "Scenario 2" baseline case with beta_N=1.8, the ELM frequency is very sensitive to the plasma triangularity. As the traingularity is increased, the plasma tends to become ELM-free and particle control via divertor cryopumping is lost. This is not an issue for high beta_N plasmas, which ELM vigorously for all traingularities. | ||
| Resource Requirements: | NBI: 4 sources required. | ||
| Diagnostic Requirements: | -- | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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