TY - JOUR
T1 - Parametric Decay Wave Observation in HFS X-Mode Injection in QUEST*)
AU - Kojima, Shinichiro
AU - Elserafy, Hatem
AU - Hanada, Kazuaki
AU - Idei, Hiroshi
AU - Ikezoe, Ryuya
AU - Nagashima, Yoshihiko
AU - Hasegawa, Makoto
AU - Onchi, Takumi
AU - Kuroda, Kengoh
AU - Nakamura, Kazuo
AU - Murakami, Takahiro
AU - Fukuyama, Masaharu
AU - Kato, Ryoya
AU - Yoneda, Ryota
AU - Ono, Masayuki
AU - Ejiri, Akira
AU - Takase, Yuichi
AU - Murakami, Sadayoshi
N1 - Funding Information:
The authors are grateful to the technical staff of the QUEST group for their helpful support. This work was supported by a Grant-in-Aid for JSPS Fellows (KAKENHI grant numbers 16H02441, 24656559 and 19J12290) and the NIFS Collaboration Research Program (NIFS05KUTRO14, NIFS13KUTR093, NIFS13KUTR085 and NIFS19KUTR136).
Publisher Copyright:
© 2020 The Japan Society of Plasma Science and Nuclear Fusion Research
PY - 2020
Y1 - 2020
N2 - The parametric decay wave (PDW) caused by three-wave parametric decay process was measured in a plasma-injecting X-mode electron cyclotron wave (ECW) from the high field side (HFS) of the Q-shu University Experimental Steady-State Spherical Tokamak (QUEST). The intensity of the low-frequency PDW on the HFS X-mode injection was significantly enhanced over the O-mode ECW injection from the low field side (LFS), where the mode conversion to electron Bernstein wave (EBW) was not expected. As the comparison was executed using plasmas with the same magnetic field and injection power, the wave injection method was considered as the primary cause of the difference in the PDWexcitation. The frequency range of the low-frequency PDWwas consistent with that of the lower hybrid wave (LHW) range, which was expected to be excited during the mode conversion to EBW. The low-frequency PDWintensity evolved in response to the plasma density, plasma current and injection power. This observation suggests that the low-frequency PDW intensity is a reliable indicator for the efficient mode conversion to EBW.
AB - The parametric decay wave (PDW) caused by three-wave parametric decay process was measured in a plasma-injecting X-mode electron cyclotron wave (ECW) from the high field side (HFS) of the Q-shu University Experimental Steady-State Spherical Tokamak (QUEST). The intensity of the low-frequency PDW on the HFS X-mode injection was significantly enhanced over the O-mode ECW injection from the low field side (LFS), where the mode conversion to electron Bernstein wave (EBW) was not expected. As the comparison was executed using plasmas with the same magnetic field and injection power, the wave injection method was considered as the primary cause of the difference in the PDWexcitation. The frequency range of the low-frequency PDWwas consistent with that of the lower hybrid wave (LHW) range, which was expected to be excited during the mode conversion to EBW. The low-frequency PDWintensity evolved in response to the plasma density, plasma current and injection power. This observation suggests that the low-frequency PDW intensity is a reliable indicator for the efficient mode conversion to EBW.
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U2 - 10.1585/pfr.15.2402063
DO - 10.1585/pfr.15.2402063
M3 - Article
AN - SCOPUS:85104227505
SN - 1880-6821
VL - 15
SP - 2402063-1-2402063-6
JO - Plasma and Fusion Research
JF - Plasma and Fusion Research
ER -