Observation of energetic-ion losses induced by various mhd instabilities in the Large Helical Device (LHD)

K. Ogawa; M. Isobe; K. Toi; F. Watanabe; D. A. Spong; A. Shimizu; M. Osakabe; S. Ohdachi; S. Sakakibara

doi:10.1088/0029-5515/50/8/084005

Observation of energetic-ion losses induced by various mhd instabilities in the Large Helical Device (LHD)

K. Ogawa, M. Isobe, K. Toi, F. Watanabe, D. A. Spong, A. Shimizu, M. Osakabe, S. Ohdachi, S. Sakakibara

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Abstract

Energetic-ion losses induced by toroidicity-induced Alfvén eigenmodes (TAEs) and resistive interchange modes (RICs) were observed in neutral-beam heated plasmas of the Large Helical Device (LHD) at a relatively low toroidal magnetic field level (≤0.75 T). The energy and pitch angle of the lost ions are detected using a scintillator-based lostfast ion probe. Each instability increases the lost ions having a certain energy/pitch angle. TAE bursts preferentially induce energetic beam ions in co-passing orbits having energy from the injection energy E = 190keV down to 130 keV, while RICs expel energetic ions of E = 190 keV down to ∼130 keV in passing-toroidally trapped boundary orbits. Loss fluxes induced by these instabilities increase with different dependences on the magnetic fluctuation amplitude: nonlinear and linear dependences for TAEs and RICs, respectively.

Original language	English
Article number	084005
Journal	Nuclear Fusion
Volume	50
Issue number	8
DOIs	https://doi.org/10.1088/0029-5515/50/8/084005
State	Published - Aug 2010

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title = "Observation of energetic-ion losses induced by various mhd instabilities in the Large Helical Device (LHD)",

abstract = "Energetic-ion losses induced by toroidicity-induced Alfv{\'e}n eigenmodes (TAEs) and resistive interchange modes (RICs) were observed in neutral-beam heated plasmas of the Large Helical Device (LHD) at a relatively low toroidal magnetic field level (≤0.75 T). The energy and pitch angle of the lost ions are detected using a scintillator-based lostfast ion probe. Each instability increases the lost ions having a certain energy/pitch angle. TAE bursts preferentially induce energetic beam ions in co-passing orbits having energy from the injection energy E = 190keV down to 130 keV, while RICs expel energetic ions of E = 190 keV down to ∼130 keV in passing-toroidally trapped boundary orbits. Loss fluxes induced by these instabilities increase with different dependences on the magnetic fluctuation amplitude: nonlinear and linear dependences for TAEs and RICs, respectively.",

author = "K. Ogawa and M. Isobe and K. Toi and F. Watanabe and Spong, {D. A.} and A. Shimizu and M. Osakabe and S. Ohdachi and S. Sakakibara",

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T1 - Observation of energetic-ion losses induced by various mhd instabilities in the Large Helical Device (LHD)

AU - Ogawa, K.

AU - Isobe, M.

AU - Toi, K.

AU - Watanabe, F.

AU - Spong, D. A.

AU - Shimizu, A.

AU - Osakabe, M.

AU - Ohdachi, S.

AU - Sakakibara, S.

PY - 2010/8

Y1 - 2010/8

N2 - Energetic-ion losses induced by toroidicity-induced Alfvén eigenmodes (TAEs) and resistive interchange modes (RICs) were observed in neutral-beam heated plasmas of the Large Helical Device (LHD) at a relatively low toroidal magnetic field level (≤0.75 T). The energy and pitch angle of the lost ions are detected using a scintillator-based lostfast ion probe. Each instability increases the lost ions having a certain energy/pitch angle. TAE bursts preferentially induce energetic beam ions in co-passing orbits having energy from the injection energy E = 190keV down to 130 keV, while RICs expel energetic ions of E = 190 keV down to ∼130 keV in passing-toroidally trapped boundary orbits. Loss fluxes induced by these instabilities increase with different dependences on the magnetic fluctuation amplitude: nonlinear and linear dependences for TAEs and RICs, respectively.

AB - Energetic-ion losses induced by toroidicity-induced Alfvén eigenmodes (TAEs) and resistive interchange modes (RICs) were observed in neutral-beam heated plasmas of the Large Helical Device (LHD) at a relatively low toroidal magnetic field level (≤0.75 T). The energy and pitch angle of the lost ions are detected using a scintillator-based lostfast ion probe. Each instability increases the lost ions having a certain energy/pitch angle. TAE bursts preferentially induce energetic beam ions in co-passing orbits having energy from the injection energy E = 190keV down to 130 keV, while RICs expel energetic ions of E = 190 keV down to ∼130 keV in passing-toroidally trapped boundary orbits. Loss fluxes induced by these instabilities increase with different dependences on the magnetic fluctuation amplitude: nonlinear and linear dependences for TAEs and RICs, respectively.

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DO - 10.1088/0029-5515/50/8/084005

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VL - 50

JO - Nuclear Fusion

JF - Nuclear Fusion

IS - 8

M1 - 084005

ER -

Observation of energetic-ion losses induced by various mhd instabilities in the Large Helical Device (LHD)

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