DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 142: High Beta, Reactor Relevant Hybrid | ||
| Name: | C. Craig Petty ( |
Affiliation: | General Atomics |
| Research Area: | Core Integration (Advanced Inductive) | Presentation time: | Not requested | Co-Author(s): | -- |
| Description: | This experiment will integrate a high beta hybrid plasma (similar to shot 129323) with the reactor relevance of Te~Ti and low rotation. Up to 3MW of ECH and 1 MW of fast wave direct electron heating can be used to raise Te. The counter beams will be used to reduce the toroidal rotation rate. | ||
| Experimental Approach/Plan: | (1) Repeat shot 129323 but with better feedback control of beta_N. Desire beta_N~3.5. (2) Add core electron heating with EC (3 MW) and FW (1 MW) to bring Te and Ti together. (3) Inject counter NBI to lower the toroidal rotation rate. Can use PCS feedback control of rotation rate. (4) If 2/1 mode becomes a problem, then redirect some gyrotrons to deposit ECCD at q=2 surface. | ||
| Background: | Shot 129323 achieved beta_N>3.5 with q95~5. This beta_N is above the ideal no-wall limit, so wall stabilization is probably playing a role. However, RWM experiments showed that only a very modest amount of rotation is needed for stabilization, so there may be room to lower the rotation rate while maintain the high beta_N value. If the 2/1 NTM becomes a problem at this high beta, then some ECCD at the q=2 surface should be able to suppress this mode. The rest of the RF power (EC and FW) should be deposited close to the magnetic axis to raise Te close to Ti. The NBI heating target shot had Ti(0)=7.1 keV and Te(0)=4.8 keV, with the temperatures nearly equated for rho>0.5. Therefore, a few MW of central electron heating should be able to bring Te and Ti together. | ||
| Resource Requirements: | NBI: All 7 sources required.
EC: Minimum of 5 gyrotrons. FW: Desire >1 MW coupled to H-mode plasma. | ||
| Diagnostic Requirements: | -- | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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