TY - JOUR
T1 - Magnetic configuration effects on fast ion losses induced by fast ion driven toroidal Alfvén eigenmodes in the large helical device
AU - Ogawa, K.
AU - Isobe, M.
AU - Toi, K.
AU - Watanabe, F.
AU - Spong, D. A.
AU - Shimizu, A.
AU - Osakabe, M.
AU - Darrow, D. S.
AU - Ohdachi, S.
AU - Sakakibara, S.
PY - 2012/4
Y1 - 2012/4
N2 - Beam-ion losses induced by fast-ion-driven toroidal Alfvén eigenmodes (TAE) were measured with a scintillator-based lost fast-ion probe (SLIP) in the large helical device (LHD). The SLIP gave simultaneously the energy E and the pitch angle χ = arccos(υ ///υ) distribution of the lost fast ions. The loss fluxes were investigated for three typical magnetic configurations of R ax-vac = 3.60 m, 3.75 m, and 3.90 m, where R ax-vac is the magnetic axis position of the vacuum field. Dominant losses induced by TAEs in these three configurations were observed in the E/χ regions of 50∼190 keV/40°, 40∼170 keV/25°, and 30∼190 keV/30°, respectively. Lost-ion fluxes induced by TAEs depend clearly on the amplitude of TAE magnetic fluctuations, R ax-vac and the toroidal field strength B t. The increment of the loss fluxes has the dependence of (b TAE/B t) s. The power s increases from s = 1 to 3 with the increase of the magnetic axis position in finite beta plasmas.
AB - Beam-ion losses induced by fast-ion-driven toroidal Alfvén eigenmodes (TAE) were measured with a scintillator-based lost fast-ion probe (SLIP) in the large helical device (LHD). The SLIP gave simultaneously the energy E and the pitch angle χ = arccos(υ ///υ) distribution of the lost fast ions. The loss fluxes were investigated for three typical magnetic configurations of R ax-vac = 3.60 m, 3.75 m, and 3.90 m, where R ax-vac is the magnetic axis position of the vacuum field. Dominant losses induced by TAEs in these three configurations were observed in the E/χ regions of 50∼190 keV/40°, 40∼170 keV/25°, and 30∼190 keV/30°, respectively. Lost-ion fluxes induced by TAEs depend clearly on the amplitude of TAE magnetic fluctuations, R ax-vac and the toroidal field strength B t. The increment of the loss fluxes has the dependence of (b TAE/B t) s. The power s increases from s = 1 to 3 with the increase of the magnetic axis position in finite beta plasmas.
KW - fast ion loss
KW - the large helical device
KW - toroidal Alfvén eigenmode
UR - http://www.scopus.com/inward/record.url?scp=84860304705&partnerID=8YFLogxK
U2 - 10.1088/1009-0630/14/4/01
DO - 10.1088/1009-0630/14/4/01
M3 - Article
AN - SCOPUS:84860304705
SN - 1009-0630
VL - 14
SP - 269
EP - 272
JO - Plasma Science and Technology
JF - Plasma Science and Technology
IS - 4
ER -