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

Yang, Cheng; Bonoli, P. T.; Wright, J. C.; Ding, Bojiang; Parker, R.; Shiraiwa, S.; Li, M H

doi:10.1088/0741-3335/56/12/125003

Cited by 23 publications

(23 citation statements)

References 49 publications

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“…2014; Yang et al. 2014). However, after the rewrite of the formulation performed in this work, the velocity-space convergence requirements of the were reanalysed.…”

Section: The Non-maxwellian Torlh/cql3d Modelmentioning

confidence: 99%

Verifying raytracing/Fokker–Planck lower-hybrid current drive predictions with self-consistent full-wave/Fokker–Planck simulations

et al. 2022

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Raytracing/Fokker–Planck (FP) simulations used to model lower-hybrid current drive (LHCD) often fail to reproduce experimental results, particularly when LHCD is weakly damped. A proposed reason for this discrepancy is the lack of ‘full-wave’ effects, such as diffraction and interference, in raytracing simulations and the breakdown of the raytracing approximation. Previous studies of LHCD using non-Maxwellian full-wave/FP simulations have been performed, but these simulations were not self-consistent and enforced power conservation between the FP and full-wave code using a numerical rescaling factor. Here, we have created a fully self-consistent full-wave/FP model for LHCD that is automatically power conserving. This was accomplished by coupling an overhauled version of the non-Maxwellian TORLH full-wave solver and the CQL3D FP code using the Integrated Plasma Simulator. We performed converged full-wave/FP simulations of Alcator C-Mod discharges and compared them with raytracing. We found that excellent agreement in the power deposition profiles from raytracing and TORLH could be obtained, however, TORLH had somewhat lower current drive efficiency and broader power deposition profiles in some cases. This discrepancy appears to be a result of numerical limitations present in the TORLH model and a small amount of diffractional broadening of the TORLH wave spectrum. Our results suggest full-wave simulation of LHCD is likely not necessary as diffraction and interference represented only a small correction that could not account for the differences between simulations and experiment.

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“…2014; Yang et al. 2014). However, after the rewrite of the formulation performed in this work, the velocity-space convergence requirements of the were reanalysed.…”

Section: The Non-maxwellian Torlh/cql3d Modelmentioning

confidence: 99%

Verifying raytracing/Fokker–Planck lower-hybrid current drive predictions with self-consistent full-wave/Fokker–Planck simulations

et al. 2022

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“…2. This is a much greater value of N ψ than that used in prior studies [30,28,27,19,47], and as FE convergence can have a non-negligible effect on power deposition, using sufficient N ψ is important to effectively compare full-wave simulations versus raytracing. In cases where plasmas are strongly shaped or there is a large pedestal, such as the DIII-D simulations performed in Sec.…”

Section: 12mentioning

confidence: 99%

An Assessment Of Full Wave Effects On Maxwellian Lower Hybrid Wave Damping

Frank¹,

Wright²,

Hutchinson³

et al. 2022

Preprint

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Lower-hybrid current drive (LHCD) actuators are important components of modern day fusion experiments as well as proposed fusion reactors. However, simulations of LHCD often differ substantially from experimental results, and from each other, especially in the inferred power deposition profile shape. Here we investigate some possible causes of this discrepancy; "full-wave" effects such as interference and diffraction, which are omitted from standard raytracing simulations and the breakdown of the raytracing near reflections and caustics. We compare raytracing simulations to state-of-the-art full-wave simulations using matched hot-plasma dielectric tensors in realistic tokamak scenarios for the first time. We show that differences between fullwave simulations and raytracing in previous work were primarily due to numerical and physical inconsistencies in the simulations, and we demonstrate that good agreement between raytracing and full-wave simulations can be obtained in reactor relevantscenarios with large ray caustics and in situations with weak damping.

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“…The time scale for momentum transport is close to the confinement time scale of particle and/or energy. For simplicity we could assume that all of these forces act on the bulk ions, since the fast-electron-ion collision time (< 1 ms) is much less than the fast-electron confinement time (∼100 ms [30] ) in the following LHCD case and the ion-ion collision time (< 1 ms) is much less than the energy confinement time (∼150 ms [31] ) in the following MC ICRH case.…”

Section: Effective Local Rf Forces In a Steady Statementioning

confidence: 99%

“…1 in Ref. [30]) are considered. The raytracing code GENRAY [33] is used to generate the power and wave-number variations along the trace for every ray.…”

Section: Lhcd On East Plasmamentioning

confidence: 99%

Tokamak Plasma Flows Induced by Local RF Forces

Chen

Gao

2015

Plasma Sci. Technol.

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The tokamak plasma flows induced by the local radio frequency (RF) forces in the core region are analyzed. The effective components of local RF forces are composed of the momentum absorption term and the resonant parallel momentum transport term (i.e. the parallel component of the resonant ponderomotive forces). Different momentum balance relations are employed to calculate the plasma flows depending on different assumptions of momentum transport. With the RF fields solved from RF simulation codes, the toroidal and poloidal flows by these forces under the lower hybrid current drive and the mode conversion ion cyclotron resonance heating on EAST-like plasmas are evaluated.

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

Cited by 23 publications

References 49 publications

Verifying raytracing/Fokker–Planck lower-hybrid current drive predictions with self-consistent full-wave/Fokker–Planck simulations

Verifying raytracing/Fokker–Planck lower-hybrid current drive predictions with self-consistent full-wave/Fokker–Planck simulations

An Assessment Of Full Wave Effects On Maxwellian Lower Hybrid Wave Damping

Tokamak Plasma Flows Induced by Local RF Forces

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