Observation of direct electron heating by the fast waves in the lower-hybrid range of frequencies in the JFT-2M tokamak

Yamamoto, T.; Uesugi, Yoshihiko; Kawashima, H.; Hoshino, K.; Aikawa, Hiroshi; Kasai, S.; Kawakami, T.; Kondoh, T.; Maeda, Hideaki; Matsuda, T.; Matsumoto, Haruhisa; Miura, Y.; Mori, Masahiro; Odajima, K.; Ogawa, Hideyuki; Ogawa, T.; Ohasa, K.; Ohtsuka, H.; Sengoku, S.; Shoji, T.; Suzuki, Norio; Tamai, Hiroshi; Yamauchi, Toshihiko; Nakazawa, I.

doi:10.1103/physrevlett.63.1148

Cited by 24 publications

(5 citation statements)

References 10 publications

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“…The plasma current was driven at a density 50 times higher than the LH density where co = w LH . Recently, an attempt was made to demonstrate fast wave current drive in a more standard tokamak plasma on JFT-2M [12]. Electron heating was observed, but there was no evidence of fast wave current drive.…”

Section: Introductionmentioning

confidence: 99%

Perpendicular Ferromagnetic-Resonance Equations Derived by Effective Demagnetizing Factors

Kohmoto¹

2003

Jpn. J. Appl. Phys.

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Fast wave absorption and heating at a relatively high ion cyclotron harmonic (u> = 6ft D ) were studied on JIPP T-IIU. In spite of the low absorption efficiency predicted by a simple theory for present experimental parameters, appreciable electron and ion heating was observed. Heating is most effective at relatively low densities (n e = 1 x 10 19 m" 3 ). An ion tail on the majority deuterium energy spectrum was observed, but not an ion tail on the minority hydrogen spectrum, which suggests the possibility of direct absorption of mode converted ion Bernstein wave power by deuterium ions. * Permanent address:

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Section: Introductionmentioning

confidence: 99%

Perpendicular Ferromagnetic-Resonance Equations Derived by Effective Demagnetizing Factors

Kohmoto¹

2003

Jpn. J. Appl. Phys.

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“…and L x /) e < 1, one obtains the following equation for the lower hybrid wave: (10) where the dielectric function e_ f w_, k-J of the lower hybrid wave is given by: (11) ktm e and the term ^-IJ>EQ X is given by: t -ex r' -ey + ,. I o 4?ren (12) where F_j( =l , e ) x , F-j y , and F_j z are x, y, and z components, respectively, of Fj( =i^ (see (9)) at…”

Section: A High-frequency Wave Dynamicsmentioning

confidence: 99%

“…Current drive by a fast wave has been performed in several toroidal devices [6], [7] and tokamaks [8]- [10]. The experiments on the tokamaks [8], however, have not conclusively shown that fast wave current drive can be achieved by means of electron Landau damping of the fast waves launched directly, possibly due to conversion of the fast waves to slow waves.…”

Section: Introductionmentioning

confidence: 99%

Parametric decay instabilities of the fast wave in the lower hybrid frequency regime

Kumar

Sharma

Tripathi

et al. 1991

IEEE Trans. Plasma Sci.

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This paper presents three possible decay instabilities of the fast wave in the lower hybrid frequency regime. It has been considered that a fast wave may decay into a highfrequency, lower hybrid wave and a low-frequency wave, either the ion-Bernstein wave, ion-acoustic wave, or kinetic Alfven wave. Explicit expressions for growth rates, homogeneous thresholds, and convective thresholds have been given. Applications have been pointed out in tokamak plasmas during current drive experiments and magnetospheric plasmas. For example, for PLT tokamak parameters, the convective threshold for the decay instability of the fast wave into lower hybrid and ion acoustic waves comes out to be ~18O W/cm 2 .

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“…In addition, it was considered to be more viable from an engineering perspective, being implemented with a high-power RF source and launcher. However, in several experiments, a density limit similar to LHCD was observed, or the current drive efficiency was too low to confirm the effect clearly [17][18][19]. The cause was speculated to be due to parasitic coupling to slow waves at the edge region or the parametric decay of the slow wave mode-converted from the launched fast wave [20,21].…”

Section: Introductionmentioning

confidence: 99%

Current drive by using lower hybrid fast wave in VEST

Kim,

Jo,

Wang

et al. 2024

Nucl. Fusion

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An efficient central or off-axis current drive is necessary for the steady-state operation of tokamak fusion reactors. The fast wave branch in the frequency range above two times the lower hybrid resonance frequency at high density, the so-called LHFW, could be such an efficient current drive scheme in high density and high temperature of reactor-grade tokamak plasmas. This is because it has a higher parallel wave electric field for efficient Landau damping, compared to the fast wave branches in other frequency ranges, and it can more deeply penetrate high density plasmas than the slow wave in the same frequency range. An experimental study has been carried out to confirm the feasibility, in collaboration with KAERI, SNU, KWU, and KAPRA, in VEST. The results show that plasma current can be driven by the fast electrons generated by the LHFW. The details are reported including the theoretical background and RF system as well as the experiment results.

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Observation of direct electron heating by the fast waves in the lower-hybrid range of frequencies in the JFT-2M tokamak

Cited by 24 publications

References 10 publications

Perpendicular Ferromagnetic-Resonance Equations Derived by Effective Demagnetizing Factors

Perpendicular Ferromagnetic-Resonance Equations Derived by Effective Demagnetizing Factors

Parametric decay instabilities of the fast wave in the lower hybrid frequency regime

Current drive by using lower hybrid fast wave in VEST

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