Investigation of Multi-Mode MHD Behavior in Shaped HBT-EP Discharges
Abstract
We report on investigations into the effect on multimode MHD of a newly installed poloidal field (PF) coil. The coil will allow the circular, limited HBT-EP to follow the main thrust of research towards a fusion reactor, which has been directed toward plasmas that are shaped and diverted. The coil shapes the high field side of the plasma up to and including imposing a PF null, while retaining compatibility with existing diagnostics and control systems. Multimode dynamics have been detected in naturally-rotating kink modes and during the response to 3D resonant magnetic perturbations. Shaping changes both the resonant helical characteristics of MHD instabilities and the plasma response to external excitation and active control. Calculations using the TokaMac and DCON codes have predicted that the coupling between the two least stable MHD kink modes would be reduced when edge q* is near resonance. The RMP response, mode structure, and multi-mode content of diverted plasmas are compared to limited ones. Preliminary results show shaping changes the relative strengths of the n = 1 and n = 2 modes.
Supported by DOE Grant DE-FG02-86ER532220- Publication:
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APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- October 2014
- Bibcode:
- 2014APS..DPPNP8048B