Full wave effects on the lower hybrid wave spectrum and driven current profile in tokamak plasmas

Shiraiwa, S.; Ko, Jinseok; Meneghini, O.; Parker, R.; Schmidt, Andréa; Scott, Steve; Greenwald, M.; Hubbard, A.; Hughes, J. W.; Ma, Y.; Podpaly, Y.; Rice, J.E.; Wallace, G.; Wilson, J. R.; Wolfe, S.; Group, Alcator

doi:10.1063/1.3609835

Cited by 40 publications

(47 citation statements)

References 29 publications

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“…The development of full-wave electromagnetic field solvers in the LHRF regime has helped to resolve some of the uncertainties related to proper treatment of weak absorption regimes, since reflection of the wave from caustic surfaces in the core and cut-offs in the edge plasma are now treated properly within the full-wave framework. Results from full-wave field simulations reported by Wright and Shiraiwa [Wright, 2009] [Shiraiwa, 2011] showed that power absorption profiles from ray tracing and full-wave calculations were qualitatively similar, despite breakdown of the geometrical optics approximation at cut-offs and caustic surfaces. Simulations performed by Shiraiwa and Meneghini did find broader absorption profiles caused by large variations in the parallel wave number near the plasma edge, just inside the closed flux surface [Shiraiwa, 2011] [Meneghini, 2012].…”

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confidence: 99%

Modelling of the EAST lower-hybrid current drive experiment using GENRAY/CQL3D and TORLH/CQL3D

Yang

Bonoli

Wright

et al. 2014

Plasma Phys. Control. Fusion

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Abstract:The coupled GENRAY-CQL3D code has been used to do systematic ray-tracing and Fokker-Planck analysis for EAST Lower Hybrid wave Current Drive (LHCD) experiments. Despite being in the weak absorption regime, the experimental level of LH current drive is successfully simulated, by taking into account the variations in the parallel wavenumber due to the toroidal effect. The effect of radial transport of the fast LH electrons in EAST has also been studied, which shows that a modest amount of radial transport diffusion can redistribute the fast LH current significantly. Taking advantage of the new capability in GENRAY, the actual Scrape Off Layer (SOL) model with magnetic field, density, temperature, and geometry is included in the simulation for both the lower and the higher density cases, so that the collisional losses of Lower Hybrid Wave (LHW) power in the SOL has been accounted for, which together with fast electron losses can reproduce the LHCD experimental observations in different discharges of EAST. We have also analyzed EAST discharges where there is a significant ohmic contribution to the total current, and good agreement with experiment in terms of total current has been obtained. Also, the full-wave code TORLH has been used for the simulation of the LH physics in the EAST, including full-wave effects such as diffraction and focusing which may also play an important role in bridging the spectral gap. The comparisons between the GENRAY and the TORLH codes are done for both the Maxwellian and the quasi-linear electron Landau damping cases. These simulations represent an important addition

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confidence: 99%

Modelling of the EAST lower-hybrid current drive experiment using GENRAY/CQL3D and TORLH/CQL3D

Yang

Bonoli

Wright

et al. 2014

Plasma Phys. Control. Fusion

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“…Later we used the LHEAF full wave code [6]. The full wave code can predict wave number spectrum spreading in plasma more accurately, which tends to be broader than what is predicted with WKB approximation [7]. This may increase the power absorbed in colder region, and thereby reduces the overall current drive efficiency.…”

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confidence: 99%

Impact of SOL plasma profiles on lower hybrid current drive: Experimental evidence, mitigation and modeling approaches

Shiraiwa

Baek

Faust

et al. 2015

AIP Conference Proceedings

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“…347,351 • Developed the first full-wave LH codes, using these to explain the decrease in current drive efficiency at high densities. 304,358,361,366,399 • Showed the importance of spatial asymmetries and fast dynamics for disruption halo currents and disruption mitigation radiation.…”

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20 years of research on the Alcator C-Mod tokamak

et al. 2014

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The object of this review is to summarize the achievements of research on the Alcator C-Mod tokamak [Hutchinson et al., Phys. Plasmas 1, 1511 and Marmar, Fusion Sci. Technol. 51, 261 (2007)] and to place that research in the context of the quest for practical fusion energy. C-Mod is a compact, high-field tokamak, whose unique design and operating parameters have produced a wealth of new and important results since it began operation in 1993, contributing data that extends tests of critical physical models into new parameter ranges and into new regimes. Using only highpower radio frequency (RF) waves for heating and current drive with innovative launching structures, C-Mod operates routinely at reactor level power densities and achieves plasma pressures higher than any other toroidal confinement device. C-Mod spearheaded the development of the vertical-target divertor and has always operated with high-Z metal plasma facing componentsapproaches subsequently adopted for ITER. C-Mod has made ground-breaking discoveries in divertor physics and plasma-material interactions at reactor-like power and particle fluxes and elucidated a) Paper AR1 1, Bull. Am. Phys. Soc. 58, 21 (2013). b) Invited speaker.

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Full wave effects on the lower hybrid wave spectrum and driven current profile in tokamak plasmas

Cited by 40 publications

References 29 publications

Modelling of the EAST lower-hybrid current drive experiment using GENRAY/CQL3D and TORLH/CQL3D

Modelling of the EAST lower-hybrid current drive experiment using GENRAY/CQL3D and TORLH/CQL3D

Impact of SOL plasma profiles on lower hybrid current drive: Experimental evidence, mitigation and modeling approaches

20 years of research on the Alcator C-Mod tokamak

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