Selective Electron-Cyclotron Heating at Down-Shifted Frequency in the Lower-Hybrid-Current-Driven Plasma on the JFT-2M Tokamak

Yamamoto, T.; Hoshino, K.; Kawashima, H.; Uesugi, Yoshihiko; Mori, Masahiro; Suzuki, Norio; Ohta, Kazuya; Matoba, T.; Kasai, S.; Kawakami, T.; Maeno, Masaki; Matsuda, T.; Matsumoto, Hiroshi; Miura, Y.; Ochiai, Isao; Odajima, K.; Ogawa, T.; Ogawa, Hideyuki; Ohtsuka, H.; Sengoku, S.; Shoji, T.; Tamai, Hiroshi; Tanaka, Yuki; Yamamoto, Satoru; Yamauchi, Toshihiko; Yanagisawa, Isao

doi:10.1103/physrevlett.58.2220

Cited by 30 publications

(10 citation statements)

References 17 publications

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“…The signal of 70 GHz during the ECH pulse at B t0 = 1.40 T is restricted by the capacity of the receiver. With an ECH power of less than 120 kW under the same conditions, however, no rapid change and no fluctuations of the ECE were observed [18]. Therefore, we believe that non-linear effects related with the radiation of the electromagnetic waves occur.…”

Section: Time Evolution Of Typical Dischargesmentioning

confidence: 76%

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Second harmonic electron cyclotron heating of lower hybrid current driven plasma in JFT-2M

Kawashima¹,

Yamamoto²,

Hoshino³

et al. 1991

Nucl. Fusion

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Second harmonic electron cyclotron heating for the extraordinary mode in lower hybrid current driven plasma has been investigated experimentally in the JFT-2M tokamak. Effective electron heating is observed at largely downshifted cyclotron frequencies as well as at the usual cyclotron resonance frequency. An absorption efficiency of 15% at f0/2fc0 = 0.76 is estimated from measurements of the Shafranov parameter and the diamagnetic flux (f0 is the frequency of the RF wave and fc0 is the cyclotron frequency at the plasma centre). From a measurement of the transmission of radiated microwaves the absorption efficiency is deduced. The dependences of the absorption efficiency on the toroidal magnetic field obtained from the two measurements are consistent with each other within experimental error. From measurements of the soft X-rays and the electron cyclotron emission it is deduced that there is selective perpendicular heating of the fast electrons which satisfies the relativistic cyclotron resonance condition. The absorption efficiency obtained is in reasonable agreement with a theoretical prediction taking mildly relativistic electrons into account. Selective cyclotron heating of 70 kW produces a 65 kA/s ramp-up of the lower hybrid driven plasma current; a resulting ramp-up efficiency of 30% is deduced.

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Section: Time Evolution Of Typical Dischargesmentioning

confidence: 76%

“…In this paper, we present experimental results for ECH of LHCD plasma in JFT-2M. Preliminary results have been reported in Refs [17,18]…”

Section: Introductionmentioning

confidence: 87%

Second harmonic electron cyclotron heating of lower hybrid current driven plasma in JFT-2M

Kawashima¹,

Yamamoto²,

Hoshino³

et al. 1991

Nucl. Fusion

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“…[17,18] The basic property of the synergy current driven by combined LHW and ECW is that the total current (𝐼 LH+EC ) driven by the two waves simultaneously is larger than the sum (𝐼 LH + 𝐼 EC ) of the currents driven by the two waves separately. The experiments on WT-2, [8,9] JFT-2M [10,11] and WT3 [12,13] showed that the currents ramped up during LHCD and ECCD, but it could not be concluded that 𝐼 LH+EC >𝐼 LH +𝐼 EC . Qualitative demonstration of the synergy effect was conducted on FTU [14] under a steady-state condition.…”

mentioning

confidence: 94%

Synergy Current Driven by Combined Lower Hybrid Wave and Different Polarized Electron Cyclotron Wave in Tokamak Plasma

Chen

Tang

Zhang

2013

Chinese Phys. Lett.

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The synergy current driven by combined lower hybrid wave (LHW) and electron cyclotron wave (ECW) in two different polarizations is studied. It is shown that improvement of the current drive efficiency can be obtained during the synergy current drive, using either the fundamental ordinary mode (1O-mode) or the second harmonic extraordinary mode (2X-mode) ECW. Detailed comparison of using the two modes reveals that the 1O-mode is more effective than the 2X-mode. It is also found that the synergy current driven by LHW and 2X-mode ECW is more likely to become negative when the power of ECW is higher than that of LHW.

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“…Fidone first proposed in the 1980's [1] that the I EC+LH , which is defined as the total current driven by the ECW and LHW simultaneously, is larger than the sum (I EC + I LH ) of the currents driven by the ECW and LHW separately, i.e., I EC+LH > I EC + I LH . Since then, theoretical and experimental studies of the synergy have been carried out in many devices, such as WT-2, [2] JFT-2M, [3] WT-3, [4] Versator II, [5] etc. In addition, several Fokker-Planck codes [6][7][8] have numerically demonstrated this phenomenon.…”

Section: Introductionmentioning

confidence: 99%

Optimized calculation of the synergy conditions between electron cyclotron current drive and lower hybrid current drive on EAST

et al. 2016

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The optimized synergy conditions between electron cyclotron current drive (ECCD) and lower hybrid current drive (LHCD) with normal parameters of the EAST tokamak are studied by using the C3PO/LUKE code based on the understanding of the synergy mechanisms so as to obtain a higher synergistic current and provide theoretical reference for the synergistic effect in the EAST experiment. The dependences of the synergistic effect on the parameters of two waves (lower hybrid wave (LHW) and electron cyclotron wave (ECW)), including the radial position of the power deposition, the power value of the LH and EC waves, and the parallel refractive indices of the LHW (N ) are presented and discussed.

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Selective Electron-Cyclotron Heating at Down-Shifted Frequency in the Lower-Hybrid-Current-Driven Plasma on the JFT-2M Tokamak

Cited by 30 publications

References 17 publications

Second harmonic electron cyclotron heating of lower hybrid current driven plasma in JFT-2M

Second harmonic electron cyclotron heating of lower hybrid current driven plasma in JFT-2M

Synergy Current Driven by Combined Lower Hybrid Wave and Different Polarized Electron Cyclotron Wave in Tokamak Plasma

Optimized calculation of the synergy conditions between electron cyclotron current drive and lower hybrid current drive on EAST

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