Phys. Rev. Lett. 103, 025003 (2009) [4 pages]Energetic-Electron-Driven Instability in the Helically Symmetric ExperimentReceived 18 February 2009; published 10 July 2009 Energetic electrons generated by electron cyclotron resonance heating are observed to drive instabilities in the quasihelically symmetric stellarator device. The coherent, global fluctuations peak in the plasma core and are measured in the frequency range of 20–120 kHz. Mode propagation is in the diamagnetic drift direction of the driving species. When quasihelical symmetry is broken, the mode is no longer observed. Experimental observations indicate that the unstable mode is acoustic rather than Alfvénic. © 2009 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevLett.103.025003
DOI:
10.1103/PhysRevLett.103.025003
PACS:
52.55.Hc, 52.25.Fi, 52.35.Bj
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