Dependence of synergy current driven by lower hybrid wave and electron cyclotron wave on the frequency and parallel refractive index of electron cyclotron wave for Tokamaks

Huang, Jie; Chen, S. Y.; Tang, C. J.

doi:10.1063/1.4861891

Cited by 3 publications

(2 citation statements)

References 19 publications

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“…This synergy effect was found in the inner half region of the Tore Supra (nor malized small radius ρ ⩽ 0.4). Negative synergy [16] was also found by simulation, the effect is dependent on the frequency and parallel refractive index of EC waves [17]. In recent experiments on the Experimental Advanced Superconducting Synergy effect of the Ohkawa current drive of electron cyclotron waves and the lower hybrid current drive: a new mechanism Tokamak (EAST), one EC and two LH waves with different frequencies are applied simultaneously [18], and a strong synergy effect among the three waves might exist [19].…”

Section: Introductionmentioning

confidence: 67%

Synergy effect of the Ohkawa current drive of electron cyclotron waves and the lower hybrid current drive: a new mechanism

et al. 2019

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A new synergy mechanism between Ohkawa current drive (OKCD) of electron cyclotron (EC) waves and lower hybrid current drive (LHCD) is discovered and discussed. And the methodology to achieve this synergy effect is also introduced. Improvement of OKCD efficiency can be achieved up to a factor of ~ 2.5 in far off-axis radial region ( > 0.6) of tokamak plasmas. Making EC wave heating the electrons of co-Ip direction and LH wave heating the electrons of counter-Ip direction, the mechanism of this new synergy effect comes from the results of electron trapping and detrapping processes. The OKCD makes the low speed barely passing electrons to be trapped (trapping process), the LHCD pulls some of the high speed barely trapped electrons out of the trapped region in velocity space (detrapping process) and accelerates the detrapped electrons to a higher speed.

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Section: Introductionmentioning

confidence: 67%

Synergy effect of the Ohkawa current drive of electron cyclotron waves and the lower hybrid current drive: a new mechanism

et al. 2019

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“…26 . Note that the use here of a second wave is essentially different from other uses of a second wave to optimize the current drive efficiency, [27][28][29][30][31][32][33][34][35] since, rather than promoting absorption by higher velocity electrons, the second wave facilitates the absorption of energy to the LH wave from the α particles. Both methods should lead to an effective increase in the efficiency.…”

Section: Summary and Discussionmentioning

confidence: 99%

Alpha channeling with high-field launch of lower hybrid waves

2015

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Although lower hybrid waves are effective at driving currents in present-day tokamaks, they are expected to interact strongly with high-energy particles in extrapolating to reactors. In the presence of a radial alpha particle birth gradient, this interaction can take the form of wave amplification rather than damping. While it is known that this amplification more easily occurs when launching from the tokamak high-field side, the extent of this amplification has not been made quantitative. Here, by tracing rays launched from the highfield-side of a tokamak, the required radial gradients to achieve amplification are calculated for a temperature and density regime consistent with a hot-ion-mode fusion reactor. These simulations, while valid only in the linear regime of wave amplification, nonetheless illustrate the possibilities for wave amplification using high-field launch of the lower hybrid wave.

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Current drive with combined electron cyclotron wave and high harmonic fast wave in tokamak plasmas

Gong

Dong

et al. 2016

Physics of Plasmas

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The current driven by combined electron cyclotron wave (ECW) and high harmonic fast wave is investigated using the GENRAY/CQL3D package. It is shown that no significant synergetic current is found in a range of cases with a combined ECW and fast wave (FW). This result is consistent with a previous study [Harvey et al., in Proceedings of IAEA TCM on Fast Wave Current Drive in Reactor Scale Tokamaks (Synergy and Complimentarily with LHCD and ECRH), Arles, France, IAEA, Vienna, 1991]. However, a positive synergy effect does appear with the FW in the lower hybrid range of frequencies. This positive synergy effect can be explained using a picture of the electron distribution function induced by the ECW and a very high harmonic fast wave (helicon). The dependence of the synergy effect on the radial position of the power deposition, the wave power, the wave frequency, and the parallel refractive index is also analyzed, both numerically and physically.

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Dependence of synergy current driven by lower hybrid wave and electron cyclotron wave on the frequency and parallel refractive index of electron cyclotron wave for Tokamaks

Cited by 3 publications

References 19 publications

Synergy effect of the Ohkawa current drive of electron cyclotron waves and the lower hybrid current drive: a new mechanism

Synergy effect of the Ohkawa current drive of electron cyclotron waves and the lower hybrid current drive: a new mechanism

Alpha channeling with high-field launch of lower hybrid waves

Current drive with combined electron cyclotron wave and high harmonic fast wave in tokamak plasmas

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