Observation of MHD Instabilities Driven by Energetic Electrons in the Large Helical Device

Mitsutaka ISOBE; Kunihiro OGAWA; Akihiro SHIMIZU; Masaki OSAKABE; Shin KUBO; K. TOI; the LHD Experiment Group

doi:10.1088/1009-0630/17/4/03

Plasma Science and Technology > 2015 > 17(4): 276-279. > DOI: 10.1088/1009-0630/17/4/03

Mitsutaka ISOBE, Kunihiro OGAWA, Akihiro SHIMIZU, Masaki OSAKABE, Shin KUBO, K. TOI, the LHD Experiment Group. Observation of MHD Instabilities Driven by Energetic Electrons in the Large Helical Device[J]. Plasma Science and Technology, 2015, 17(4): 276-279. DOI: 10.1088/1009-0630/17/4/03

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Observation of MHD Instabilities Driven by Energetic Electrons in the Large Helical Device

1 National Institute for Fusion Science, Toki 509-5292, Japan 2 Department of Fusion Science, The Graduate University for Advanced Studies (SOKENDAI), Toki 509-5292, Japan 3 Department of Energy Engineering and Science, Nagoya University, Nagoya 464-8463, Japan

Funds: supported by the Grant-in-Aid for Encouragement of Scientists from the Japan Society for the Promotion of Science (No. 20656150). This work was also partly supported by the JSPS-NRF-NSFC A3 Foresight Program in the field of Plasma Physics (NSFC: No. 11261140328 and NRF: No. 2012K2A2A6000443)

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Received Date: August 01, 2014

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Abstract

Abstract

Coherent magnetic fluctuations in an acoustic range of frequency have been regu- larly observed in low-density (n e < 0.2×10 ¹⁹ m ⁻³ ) plasmas with strong second harmonic electron cyclotron resonance heating (ECRH) on the Large Helical Device. Hard X-ray measurements indi- cated that energetic electrons are generated in these ECRH discharges. The magnetic fluctuations are suppressed in higher density discharges where energetic electrons are not present. The ECRH power modulation experiment indicated that the observed magnetohydrodynamic (MHD) mode has an acoustic nature rather than an Alfv´ enic nature.
- LHD,
- ECRH,
- energetic electron,
- MHD instability

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