DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 65: Simulation of Alpha Channeling Current Drive | ||
| Name: | C. Craig Petty ( |
Affiliation: | General Atomics |
| Research Area: | Heating & Current Drive | Presentation time: | Not requested | Co-Author(s): | K. L. Wong, W. W. Heidbrink |
| Description: | Demonstrate the practicality of using TAE's to selectively sweep co-moving energetic particles to larger radius, resulting in localized current drive to reduce or reverse the central magnetic shear even if the initial fast particle population is isotropic. Use the fast D-alpha diagnostic to verify the redistribution of energetic ions. | ||
| Experimental Approach/Plan: | (1) Inject balanced beams into low current L-mode plasma. Optimize the beam sources for the collection of MSE data. (2) Decrease the plasma density until the TAE's become unstable. Document the change in the current profile. (3) Compare with different NBI power levels and different mix of left and right sources. (4) Compare with co-only NBI and counter-only NBI. | ||
| Background: | Previous experiments on DIII-D with co-NBI showed that TAE modes can displace the energetic particles to larger radius, broadening the noninductuve current drive profile. This can be thought of as a simulation of the alpha channeling effect in a burning plasma. Since only co-moving fast ions can resonate with the TAE's and get ejected from the core towards the edge, this process allows local noninductive current drive to be obtained from an initially isotropic alpha particle distribution. To better simulate this alpha channeling effect on DIII-D, we will inject balanced beams and then use the TAE's to spatially separate the co-moving and counter-moving fast ions. While this may not result in much net current drive, it should dramatically change the magnetic shear profile. The spatial redistribution of the energetic ions can also be verified by the total pressure profile determined by the MSE diagnostic, and the fast D-alpha diagnostic. | ||
| Resource Requirements: | NBI: Co and counter MSE beamlines (4 sources total). | ||
| Diagnostic Requirements: | MSE is critical. | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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