DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 247: BetaN=5 for 2 seconds | ||
| Name: | Andrea M. Garofalo ( |
Affiliation: | Columbia University |
| Research Area: | Core Integration (Steady-State Scenario) | Presentation time: | Not requested | Co-Author(s): | C. Holcomb, E. Doyle |
| Description: | Demonstrate sustained betaN~5 for at least ~2 seconds. Use Ip and Bt ramps if necessary to maintain NTM stability by driving current at large minor radius, as in discharge 122004. Use counter-current drive to compensate bootstrap current overdrive as betaN is pushed above 4. | ||
| Experimental Approach/Plan: | A key requirement to sustain betan >4 is the sustainment of qmin>2. - This requires counter-current drive just inside the radius of qmin, possibly combined with co-current drive outside the radius of qmin.
For efficient ECCD current drive, we will need to develop better density control than in discharge 122004. This will require tweaking the plasma shape to take advantage of the lower divertor high-triangularity pump, not available at the time of shot 122004. With the energy confinement of shot 122004, 5 NBI co-Ip sources should allow reaching betan=4.5. We propose to investigate reducing the Ip ramp rate to both help reducing the density rise, and make available more NBI power to push betan toward 5. Lowering the toroidal field may also be a viable way to make more co-Ip NBI power available. | ||
| Background: | The target for the DIII-D 5 year plan is to achieve betaN~5 in steady state. An intermediate step would be the long pulse demonstration of betan=5, i.e. sustained but not necessarily steady-state. Experiments in 2005 have demonstrated betan~4 for 2 seconds, and have shown the possibility for stable betaN=5, if qmin is above 2. | ||
| Resource Requirements: | All 5 co-Ip NBI sources. 4 or more gyrotrons for ECCD. | ||
| Diagnostic Requirements: | -- | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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