Electron heat transport in shaped TCV L-mode plasmas

Camenen, Y.; Pochelon, A.; Bottino, A.; Coda, S.; Ryter, F.; Sauter, O.; Behn, R.; Goodman, T. P.; Henderson, M.; Karpushov, A.; Porte, L.; Zhuang, G.

doi:10.1088/0741-3335/47/11/007

Cited by 34 publications

(39 citation statements)

References 37 publications

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“…Gyro-kinetic stability analysis indicated that the TEM are the dominant modes [21]. Similar experiments repeated in DIII-D [33] and TCV [34] yielded comparable results.…”

Section: Perturbative Heat Transport Results In L-and H-mode Plasmas supporting

confidence: 52%

Perturbative studies of turbulent transport in fusion plasmas

Mantica¹,

Ryter

2006

Comptes Rendus. Physique

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One powerful way to investigate transport is to study the dynamic plasma response to externally applied small perturbations. This paper describes the experimental techniques and basic theory underlying the perturbative approach. It then reviews the most recent results on electron heat transport and discusses their interpretation based on key concepts from electrostatic turbulence theory. Finally it presents some hints for future extensions of the work. RésuméUne puissante méthode d'investigation du transport dans les plasmas consiste à étudier sa réponse dynamique à une excitation extérieure. Ce papier décrit les techniques expérimentales et la théorie de base de l'approche dynamique. Ensuite, les résultats essentiels obtenus sur le transport électronique de la chaleur sont décrits et leur interprétation est discutée sur la base des concepts déduits de la théorie du transport électrostatique turbulent. Finalement, de possibles futures extensions de cette méthode sont suggérées.

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“…Gyro-kinetic stability analysis indicated that the TEM are the dominant modes [21]. Similar experiments repeated in DIII-D [33] and TCV [34] yielded comparable results.…”

Section: Perturbative Heat Transport Results In L-and H-mode Plasmas supporting

confidence: 52%

Perturbative studies of turbulent transport in fusion plasmas

Mantica¹,

Ryter

2006

Comptes Rendus. Physique

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“…16 Experimental evidence for profile stiffness and critical gradients is also found in several tokamaks. [17][18][19][20][21][22][23] As a consequence of stiff transport in the plasma core, the edge temperature provides the key boundary condition dictating overall plasma performance. 10,14,24 This means that in very stiff core plasmas, like many H-modes, small decreases/increases in local temperature gradients can lead to large decreases/increases in local diffusivity.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear gyrokinetic simulations of the I-mode high confinement regime and comparisons with experimenta)

et al. 2015

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For the first time, nonlinear gyrokinetic simulations of I-mode plasmas are performed and compared with experiment. I-mode is a high confinement regime, featuring energy confinement similar to H-mode, but without enhanced particle and impurity particle confinement [D. G. Whyte et al., Nucl. Fusion 50, 105005 (2010)]. As a consequence of the separation between heat and particle transport, I-mode exhibits several favorable characteristics compared to H-mode. The nonlinear gyrokinetic code GYRO [J. Candy and R. E. Waltz, J Comput. Phys. 186, 545 (2003)] is used to explore the effects of E Â B shear and profile stiffness in I-mode and compare with L-mode. The nonlinear GYRO simulations show that I-mode core ion temperature and electron temperature profiles are more stiff than L-mode core plasmas. Scans of the input E Â B shear in GYRO simulations show that E Â B shearing of turbulence is a stronger effect in the core of I-mode than L-mode. The nonlinear simulations match the observed reductions in long wavelength density fluctuation levels across the L-I transition but underestimate the reduction of long wavelength electron temperature fluctuation levels. The comparisons between experiment and gyrokinetic simulations for I-mode suggest that increased E Â B shearing of turbulence combined with increased profile stiffness are responsible for the reductions in core turbulence observed in the experiment, and that I-mode resembles H-mode plasmas more than L-mode plasmas with regards to marginal stability and temperature profile stiffness. V C 2015 AIP Publishing LLC.

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“…Indirect evidence supporting the existence of critical gradients has been reported in tokamaks for both electron and ion thermal transport. [2][3][4][5][6] Validation for the existence of critical gradients in fusion experiments requires direct, local measurements of the fluctuations that are driving the transport. Direct, systematic observation of instability has been related to critical gradient criteria in linear experiments; 7-9 however, no previous work exists in the core of a confined high-temperature plasma.…”

Section: Introductionmentioning

confidence: 99%

Experimental characterization of multiscale and multifield turbulence as a critical gradient threshold is surpassed in the DIII-D tokamak

et al. 2013

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A critical gradient for long wavelength (kθρs≲0.4) electron temperature fluctuations has been observed in an experiment in the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)], where below a threshold value of LTe−1=|∇Te|/Te electron temperature fluctuations are constant and above they steadily increase. Above the critical gradient, the electron heat flux inferred by power balance also increases rapidly. Critical gradients are a predicted attribute of turbulence arising from linear instabilities and are thought to be related to transport stiffness. The presented results are the first direct, systematic demonstration of critical gradient behavior in turbulence measurements in a tokamak. The experiment was performed by changing the deposition location of electron cyclotron heating shot-to-shot to locally scan LTe−1 at r/a = 0.6 in L-mode plasmas; rotation was also varied by changing the momentum input from neutral beam injection. Temperature fluctuations were measured with a correlation electron cyclotron emission (CECE) radiometry system. In addition to the CECE measurements, an array of turbulence measurements were acquired to characterize fluctuations in multiple fields and at multiple scales as LTe−1 and rotation were modified: long wavelength (kθρs≲0.5) density fluctuations were acquired with beam emission spectroscopy, the phase angle between electron temperature and density fluctuations was measured by coupling the CECE system and a reflectometer, intermediate scale (kθρs∼0.8) density fluctuations were measured with a Doppler backscattering (DBS) system, and low frequency flows were also measured with DBS. The accumulated measurements and trends constrain identification of the instability responsible for the observed critical gradient to the ∇Te-driven trapped electron mode.

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Electron heat transport in shaped TCV L-mode plasmas

Cited by 34 publications

References 37 publications

Perturbative studies of turbulent transport in fusion plasmas

Perturbative studies of turbulent transport in fusion plasmas

Nonlinear gyrokinetic simulations of the I-mode high confinement regime and comparisons with experimenta)

Experimental characterization of multiscale and multifield turbulence as a critical gradient threshold is surpassed in the DIII-D tokamak

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