New Edge Coherent Mode Providing Continuous Transport in Long-Pulse H-mode Plasmas

Wang, H.Q.; Xu, G. S.; Wan, Baonian; Ding, Siye; Guo, H.Y.; Shao, L. M.; Liu, S.C.; Xu, X. Q.; Wang, E.; Niu, Y.; Naulin, V.; Nielsen, A. H.; Rasmussen, Jens Juul; Candy, J.; Bravenec, R. V.; Sun, Yuan; Shi, Tonghui; Liang, Y.; Chen, R.; Zhang, W.; Wang, Li; Chen, L.; Zhao, Nan; Li, Y.L.; Liu, Y.L.; Hu, G.H.; Gong, X.Z.

doi:10.1103/physrevlett.112.185004

Cited by 111 publications

(160 citation statements)

References 22 publications

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“…GPI has also been used to measure the quasicoherent edge oscillations [50][51][52] and edge localized modes (ELMs). 53,54 The GPI light signal will respond to any density/temperature perturbations associated with edge instabilities and also indirectly to any radial movement of edge magnetic flux surfaces which causes local density/temperature perturbations.…”

Section: What Does Gpi Measure?mentioning

confidence: 99%

“…86 The Experimental Advanced Superconducting Tokamak (EAST) in China has installed a dual GPI system with two views located ±50 • poloidally with respect to the outer midplane, in order to evaluate the up/down symmetry of the turbulence. 51,[87][88][89] The glass fiber bundles are shielded by molybdenum tubes of 10 mm thickness to prevent darkening due to the large hard x-ray flux during lower hybrid current drive (LHCD).…”

Section: E Special Features Of Various Gpi Systemsmentioning

confidence: 99%

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Invited Review Article: Gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion devices

Zweben

Terry

Stotler

et al. 2017

Review of Scientific Instruments

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Gas puff imaging (GPI) is a diagnostic of plasma turbulence which uses a puff of neutral gas at the plasma edge to increase the local visible light emission for improved space-time resolution of plasma fluctuations. This paper reviews gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion research, with a focus on the instrumentation, diagnostic cross-checks, and interpretation issues. The gas puff imaging hardware, optics, and detectors are described for about 10 GPI systems implemented over the past ∼15 years. Comparison of GPI results with other edge turbulence diagnostic results is described, and many common features are observed. Several issues in the interpretation of GPI measurements are discussed, and potential improvements in hardware and modeling are suggested.

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Section: What Does Gpi Measure?mentioning

confidence: 99%

Section: E Special Features Of Various Gpi Systemsmentioning

confidence: 99%

Invited Review Article: Gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion devices

Zweben

Terry

Stotler

et al. 2017

Review of Scientific Instruments

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show abstract

“…Turbulence structures in ELM-free H-mode have been observed in magnetic and density fluctuations in other devices. [10][11][12][13][14][15][16][17][18][19][20][21] Low frequency outer mode (OM) at the top of the pedestal in JET indicates a mechanism to delay the appearance of the first ELM. 10 Quasi-coherent (QC) oscillation in Alcator C-Mod is interpreted as a possible mechanism to provide radial transport through the pedestal region in enhanced D a (EDA) Hmode.…”

mentioning

confidence: 99%

Observation of pedestal turbulence in edge localized mode-free H-mode on experimental advanced superconducting tokamak

Han

Zhang

et al. 2014

Physics of Plasmas

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Two different pedestal turbulence structures have been observed in edge localized mode-free phase of H-mode heated by lower hybrid wave and RF wave in ion cyclotron range of frequencies (ICRF) on experimental advanced superconducting tokamak. When the fraction of ICRF power PICRF/Ptotal exceeds 0.7, coherent mode is observed. The mode is identified as an electromagnetic mode, rotating in electron diamagnetic direction with a frequency around 50 kHz and toroidal mode number n = −3. Whereas when PICRF/Ptotal is less than 0.7, harmonic mode with frequency f = 40–300 kHz appears instead. The characteristics of these two modes are demonstrated preliminarily. The threshold value of heating power and also the plasma parameters are distinct.

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“…Fluctuation spectra showing features similar to QC modes are also observed at the very edge of the plasma in several advanced regimes (H-modes [19][20][21][22], Enhanced α D H-modes [23][24][25][26][27], I-mode [28][29][30]). There is no unified explanation for these modes which present similar QC spectral signature.…”

Section: Introductionmentioning

confidence: 99%

Discriminating the trapped electron modes contribution in density fluctuation spectra

et al. 2015

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Quasi-coherent (QC) modes have been reported for more than 10 years in reflectometry fluctuations spectra in the core region of fusion plasmas. They have characteristics in-between coherent and broadband fluctuations as they oscillate at a marked frequency but have a wide spectrum. This work presents further evidences of the link recently established between QC modes and the trapped electron modes (TEM) instabilities (Arnichand et al 2014 Nucl. Fusion 54 123017). In electron cyclotron resonance heated discharges of Tore Supra, an enhancement of QC modes amplitude is observed in a region where TEM cause impurity transport and turbulence. In JET Ohmic plasmas, QC modes disappear during density ramp-up and current ramp-down. This is reminiscent of Tore Supra and TEXTOR observations during transitions from the linear Ohmic confinement (LOC) to the saturated Ohmic confinement (SOC) regimes. Evidencing TEM activity then becomes experimentally possible via analysis of fluctuation spectra.

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New Edge Coherent Mode Providing Continuous Transport in Long-Pulse H-mode Plasmas

Cited by 111 publications

References 22 publications

Invited Review Article: Gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion devices

Invited Review Article: Gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion devices

Observation of pedestal turbulence in edge localized mode-free H-mode on experimental advanced superconducting tokamak

Discriminating the trapped electron modes contribution in density fluctuation spectra

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