Review of recent experimental and modeling advances in the understanding of lower hybrid current drive in ITER-relevant regimes

Ding, Bojiang; Bonoli, P. T.; Tuccillo, A. A.; Goniche, M.; Kirov, K.; Li, M.; Li, Yunguo; Cesario, R.; Peysson, Y.; Amicucci, L.; Baek, S. G.; Faust, I.; Parker, R.; Shiraiwa, S.; Wallace, G.; Cardinali, A.; Castaldo, C.; Ceccuzzi, S.; Mailloux, J.; Napoli, F.; Liu, F.; Wan, Baonian; Contributors, Jet

doi:10.1088/1741-4326/aad0aa

Cited by 27 publications

(24 citation statements)

References 49 publications

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“…The effect of LH frequency (2.45 GHz and 4.60 GHz) on PI has been analysed by LHPI [12] and MIT code [13] in Ref. [14], both showing that PI is stronger with 2.45GHz wave. Based on the PI modelling, the LH star suite of numerical codes [14,15] has been further utilised for calculating the driven current profile [14].…”

Section: Scenario Development With Sole Rf Heatingmentioning

confidence: 99%

Overview of EAST experiments on the development of high-performance steady-state scenario

et al. 2017

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The EAST research program aims to demonstrate steady-state long-pulse advanced high-performance H-mode operations with ITER-like poloidal configuration and RF-dominated heating schemes. Since last IAEA FEC, EAST has been upgraded with all ITER-relevant auxiliary heating and current drive systems, enabling the investigation of plasma profile control by coupling/integration of various combinations. By means of the 4.6 GHz and 2.45 GHz LHCD systems, H-mode can be obtained and maintained at relatively high density, even up to n e ~ 4.5 × 10 19 m-3 , where a current drive effect is still observed. Significant progress has been achieved on EAST, including: i). Demonstration of a steady-state scenario (fully non-inductive with V loop ~ 0.0V at high β P ~ 1.8 and high performance (H 98,y2 > 1.0) in upper single-null (ε ~ 1.6) configuration with the tungsten divertor; ii) Discovery of a stationary ELM-stable H-mode regime with 4.6 GHz LHCD; iii) achievement of ELM suppression in slowly-rotating H-mode plasma with the application of n = 1 and 2 RMPs.

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Section: Scenario Development With Sole Rf Heatingmentioning

confidence: 99%

Overview of EAST experiments on the development of high-performance steady-state scenario

et al. 2017

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“…Cases (1-4) and (8)(9)(10)(11) reveal that F ref increases with f p . Cases (3,5,6,8) reveal that F ref increases with n b /n 0 and decreases with a b . This is consistent with previous scattering theories [19,40].…”

Section: Reflection Coefficient For Turbulent Slabmentioning

confidence: 94%

“…Measurements on Alcator C-Mod [5], EAST [6], and Tore Supra [7] indicate self-similar, on-axis peaked LH current profiles. Ray-tracing/Fokker-Planck simulations predict off-axis peaks [5], which are inconsistent with these measurements.…”

Section: Introductionmentioning

confidence: 99%

A hybrid full-wave Markov chain approach to calculating radio-frequency wave scattering from Scrape-off Layer filaments

Biswas,

Shiraiwa,

Baek

et al. 2021

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The interaction of radio-frequency (RF) waves with edge turbulence modifies the incident wave-spectrum, and can significantly affect RF heating and current drive in tokamaks. Previous LH scattering models have either used the weak-turbulence approximation, or treated more realistic, filamentary turbulence in the ray-tracing limit. In this work, a new model is introduced which retains full-wave effects of RF scattering in filamentary turbulence. First, a Mie-scattering technique models the interaction of an incident wave with a single Gaussian filament. Next, an effective differential scattering-width is derived for a statistical ensemble of filaments. Lastly, a Markov chain solves for the transmitted wave-spectrum in slab geometry. This model is applied to LH launch for current drive. The resulting wave-spectrum is asymmetrically broadened in wave-number angle-space. This asymmetry is not accounted for in previous LH scattering models. The modified wave-spectrum is coupled to a ray-tracing/Fokker-Planck solver (GENRAY/CQL3D) to study its impact on current drive. The resulting current profile is greatly altered, and there is significant increase in on-axis current and decrease in off-axis peaks. This is attributed to a portion of the modified wave-spectrum that strongly damps on-axis during first-pass.

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“…As indicated by the parametric instability (PI) measurement by a radio frequency (RF) loop antenna (Fig. 4), it is speculated to [11] has been further utilised for calculating the driven current profile [6]. Due to the PI effect, the power deposited in the edge region, which cannot contribute to useful LHCD mechanism, is different, leading to a different LH current profile.…”

Section: Fig 2 Demonstration Of Lh Spectrum On Controlling Current mentioning

confidence: 99%

Recent progress of RF-dominated experiments on EAST

et al. 2017

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Abstract. The research of EAST program is mostly focused on the development of high performance steady state scenario with ITER-like poloidal configuration and RF-dominated heating schemes. With the enhanced ITER-relevant auxiliary heating and current drive systems, the plasma profile control by coupling/integration of various combinations has been investigated, including lower hybrid current drive (LHCD), electron cyclotron resonance heating (ECRH) and ion cyclotron resonance heating (ICRH). The 12 MW ICRH system has been installed on EAST. Heating and confinement studies using the Hydrogen Minority Heating scheme have been investigated. One of the importance challenges for EAST is coupling higher power into the core plasma, experiments including changing plasma position, electron density, local gas puffing and antenna phasing scanning were performed to improve ICRF coupling efficiency on EAST. Results show that local gas injection and reducing the k|| can improve the coupling efficiency directly. By means of the 4.6 GHz and 2.45 GHz LHCD systems, H-mode can be obtained and sustained at relatively high density, even up to ne ~ 4.5 × 10 19 m -3, where a current drive effect is still observed. Meanwhile, effect of source frequency (2.45GHz and 4.6GHz) on LHCD characteristic has been studied on EAST, showing that higher frequency improves penetration of the coupled LH (lower hybrid) power into the plasma core and leads to a better effect on plasma characteristics. Studies demonstrate the role of parasitic effects of edge plasma in LHCD and the mitigation by increasing source frequency. Experiments of effect of LH spectrum and plasma density on plasma characteristics are performed, suggesting the possibility of plasma control for high performance. The development of a 4MW ECRH system is in progress for the purpose of plasma heating and MHD control. The built ECRH system with 1MW source power has been successfully put into use on EAST in 2015. H-mode discharges with L-H transition triggered by ECRH injection were obtained and its effects on the electron temperature, particle confinement and the core MHD stabilities were observed. By further exploring and optimizing the RF combination for the sole RF heating and current drive regime, fully non-inductive H-mode discharges with V loop~0 V has progressed steadily in the 2016 campaign. The overview of the significant progress of RF dominated experiments is presented in this paper.

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Review of recent experimental and modeling advances in the understanding of lower hybrid current drive in ITER-relevant regimes

Cited by 27 publications

References 49 publications

Overview of EAST experiments on the development of high-performance steady-state scenario

Overview of EAST experiments on the development of high-performance steady-state scenario

A hybrid full-wave Markov chain approach to calculating radio-frequency wave scattering from Scrape-off Layer filaments

Recent progress of RF-dominated experiments on EAST

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