TY - JOUR
T1 - HFS injection of X-mode for EBW conversion in QUEST
AU - Elserafy, Hatem
AU - Hanada, Kazuaki
AU - Kuroda, Kengoh
AU - Idei, Hiroshi
AU - Yoneda, Ryota
AU - Huang, Canbin
AU - Kojima, Shinichiro
AU - Hasegawa, Makoto
AU - Nagashima, Yoshihiko
AU - Onchi, Takumi
AU - Ikezoe, Ryuya
AU - Higashijima, Aki
AU - Nagata, Takahiro
AU - Kawasaki, Shoji
AU - Shimabukuro, Shun
AU - Bertelli, Nicola
AU - Ono, Masayuki
N1 - Funding Information:
This work was supported by a Grant-in-Aid for JSPS Fellows (KAKENHI Grant Number 16H02441, 24656559) and the NIFS Collaboration Research Program (NIFS05KUTRO14, NIFS13KUTR093, NIFS13KUTR085, and NIFS14KUTR103). This work was also supported in part by the Collaborative Research Program of the Research Institute for Applied Mechanics, Kyushu University.
Publisher Copyright:
© 2019 The Japan Society of Plasma Science and Nuclear Fusion Research.
PY - 2019
Y1 - 2019
N2 - High field side (HFS) injection of eXtra-ordinary X-mode for electron Bernstein wave (EBW) conversion was conducted in the QUEST tokamak. Radio frequency (RF; 8.2 GHz) power was delivered from the low field side (LFS) to the high field side HFS through waveguides, and from the HFS placed 20 cm above the midplane of the vacuum vessel. The aim was to compare the RF launches from the LFS and HFS. The plasma brightness, measured by a fast camera, as well as the H α signal captured along the mid-plane, was noticeably higher in the HFS launch than in the LFS launch. The HFS injection achieved a plasma current of approximately 130 A, versus 35A in the LFS injection. The electron density n e predicted from the position of the upper hybrid resonance agreed with the line-averaged n e measured by an interferometer, confirming the effective conversion and subsequent damping of the EBW mode. The RF leakage of the HFS injection was less than one-sixth that of the LFS injection. These results indicate that HFS delivers better RF coupling and conversion efficiency to EBW than LFS injection. Such efficient plasma heating via EBW will significantly enhance the plasma production.
AB - High field side (HFS) injection of eXtra-ordinary X-mode for electron Bernstein wave (EBW) conversion was conducted in the QUEST tokamak. Radio frequency (RF; 8.2 GHz) power was delivered from the low field side (LFS) to the high field side HFS through waveguides, and from the HFS placed 20 cm above the midplane of the vacuum vessel. The aim was to compare the RF launches from the LFS and HFS. The plasma brightness, measured by a fast camera, as well as the H α signal captured along the mid-plane, was noticeably higher in the HFS launch than in the LFS launch. The HFS injection achieved a plasma current of approximately 130 A, versus 35A in the LFS injection. The electron density n e predicted from the position of the upper hybrid resonance agreed with the line-averaged n e measured by an interferometer, confirming the effective conversion and subsequent damping of the EBW mode. The RF leakage of the HFS injection was less than one-sixth that of the LFS injection. These results indicate that HFS delivers better RF coupling and conversion efficiency to EBW than LFS injection. Such efficient plasma heating via EBW will significantly enhance the plasma production.
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U2 - 10.1585/pfr.14.1205038
DO - 10.1585/pfr.14.1205038
M3 - Article
AN - SCOPUS:85063647037
VL - 14
JO - Plasma and Fusion Research
JF - Plasma and Fusion Research
SN - 1880-6821
IS - 1
M1 - 1205038
ER -