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

Research output: Contribution to journal › Article › peer-review

59 Scopus citations

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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doi = "10.1088/0029-5515/50/8/084005",

language = "English",

volume = "50",

journal = "Nuclear Fusion",

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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.

UR - https://www.scopus.com/pages/publications/78149291485

U2 - 10.1088/0029-5515/50/8/084005

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

M3 - Article

AN - SCOPUS:78149291485

SN - 0029-5515

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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