DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
Login | Review | Submit | Logout | Help
Questions about this website? Contact Andrew LeBlanc Questions about ROF? Contact Chuck Greenfield
| Title | 279: Extrapolation of H-modes and Hybrids to ITER | ||
| Name: | C. Craig Petty ( |
Affiliation: | General Atomics |
| Research Area: | ITER Demonstration Discharges | Presentation time: | Not requested | Co-Author(s): | -- |
| Description: | Create discharges on DIII-D with exactly the ITER shape and dimensionless parameters identical to ITER except for rho*. Perform a rho* scan to access the extrapolation to ITER. This should be done for a hybrid plasma with beta_N>2.5, and for a "Scenario 2" plasma with beta_N=1.8.
The ITER plasma shape is not a cyropumping shape for DIII-D. In this experiment, we will use RMP from the I-coil to control the H-mode density. The I-coil has been shown to very effectively reduce the H-mode density pedestal on DIII-D. Balanced NBI should be used to give a low Mach number. | ||
| Experimental Approach/Plan: | Study small rho* plasmas first. (1) Reproduce exactly the ITER plasma shape, close to 125068 at 3700 ms but with lower triangularity. (2) For beta_N=1.8, q95=3 "ITER Scenario 2" case, need Ip=1.6 MA and Bt=1.9 T. Adjust gas puffing to obtain same collisionality as ITER. If ELM frequency is too low for effective density control, use the I-coil to reduce the density pedestal (alternatively lower the triangularity some more). (3) For large rho* comparison shot, decrease Ip to 0.8 MA and Bt to 0.95 T. Still have beta_N=1.8. Use PCS control of I-coil current to reduce density by factor-of-2.5 from the small rho* plasma. (4) Repeat rho* scan for hybrid plasma with beta_N>2.5. Same toroidal field, but plasma current is reduced to Ip=1.2-->0.6 MA to obtain q95=4. | ||
| Background: | A previous attempt at a beta_N=1.8 rho* scan in an ITER-like shape on DIII-D utilized a higher-than-ITER triangularity to optimize the divertor cyropumping. For this low beta_N value, the high triangularity resulted in a very low ELM frequency and very poor density control. This experiment will use the actual (lower) ITER value of triangularity, which will result in a higher ELM frequency, and obtain density control by means of RMP from the I-coil. | ||
| Resource Requirements: | NBI: All 7 sources required. | ||
| Diagnostic Requirements: | -- | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
Print this page