DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 307: ELM suppression by multi-harmonic RMPs | ||
| Name: | Michael J. Schaffer ( |
Affiliation: | General Atomics |
| Research Area: | ELM Control & Pedestal Physics | Presentation time: | Not requested | Co-Author(s): | Evans, Fenstermacher, Moyer, Joseph expected |
| Description: | Using special I-coil patch panel connection, apply approximately equal magnitudes of n=3 and n=2 pitch resonant magnetic perturbation fields simultaneously. Computation shows that such multi- harmonic fields can fill in some island gaps, and they also create richer stochasticity. Furthermore, depending on how the n=2 current component is distributed in the I-coil, the magnitude of side band n=4 harmonics can be varied, thus enabling a limited test of a three-harmonic RMP. Look for experimental similarities and differences with respect to conventional, pure n=3, RMP ELM suppression. | ||
| Experimental Approach/Plan: | -- | ||
| Background: | Computations of the helical Fourier spectra of magnetic fields produced by many coil concepts proposed for ITER revealed some spectral fill-in advantage to the combined use of two or more toroidal harmonics. DIII-D experiments have shown that this concept works, by adding extra n=1 from the C-coil. However, n=1 is prone to unstable mode locking. Pitch resonant n=2 can be made by the I-coil, and it is expected to induce less mode locking than n=1. | ||
| Resource Requirements: | Special I-coil patch panel connections. | ||
| Diagnostic Requirements: | -- | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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