The excitation mechanism for low-n edge harmonic oscillations in quiescent H-mode regimes is identified analytically. We show that the combined effect of diamagnetic and poloidal magnetohydrodynamic flows, with the constraint of a Doppler-like effect of the ion flow, leads to the stabilization of short wavelength modes, allowing low-n perturbation to grow. The analysis, performed in tokamak toroidal geometry, includes the effects of large edge pressure gradients, associated with the local flattening of the safety factor and diamagnetic flows, sheared parallel and E x B rotation, and a vacuum region between plasma and the ideal metallic wall. The separatrix also is modeled analytically.
Excitation Mechanism of Low-n Edge Harmonic Oscillations in Edge Localized Mode-Free, High Performance, Tokamak Plasmas
Brunetti, D.; Graves, J. P.; Lazzaro, E.; Mariani, A.; Nowak, S.; Cooper, W. A.; Wahlberg, C.
ID | 402898 |
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DOI | 10.1103/PhysRevLett.122.155003 |
PRODUCT TYPE | Journal Article |
LAST UPDATE | 2022-06-19T07:27:58Z |
EU PROJECT | EUROfusion |
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TITLE | Implementation of activities described in the Roadmap to Fusion during Horizon 2020 through a Joint programme of the members of the EUROfusion consortium |
FOUNDING PROGRAM | H2020 |