Evolution of ETG mode scale turbulence and anomalous electron transport in dynamic tokamak experiments

Gurchenko, A. D.; Gusakov, E. Z.

doi:10.1088/0741-3335/52/12/124035

Cited by 21 publications

(28 citation statements)

References 28 publications

(75 reference statements)

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“…22, was used for the ETG mode studies using the enhanced scattering in the upper hybrid resonance. 23,24 In the present experiment, it was used in standard DR measurements utilizing the quadrature detection scheme. The DR spectrum was obtained via averaging over 155 random DR power spectra obtained by using Fourier transform of successive 12.8 ls samples of the DR signal.…”

Section: The Experimental Approachmentioning

confidence: 99%

Fast synthetic X-mode Doppler reflectometry diagnostics for the full-f global gyrokinetic modeling of the FT-2 tokamak

et al. 2018

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Section: The Experimental Approachmentioning

confidence: 99%

Fast synthetic X-mode Doppler reflectometry diagnostics for the full-f global gyrokinetic modeling of the FT-2 tokamak

et al. 2018

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“…Recent direct measurements using the Doppler back-scattering system installed on MAST [36] are consistent with small-scale turbulence due to ETG. Gurchenko and Gusakov [37] established an experimental correlation in several devices between electron-scale turbulence and anomalous electron transport, but not a causation pathway directly attributing the transport to ETG. The transport scaling that we obtain here derives from, and may, therefore, be an experimental signature for, not only the presence of electron-scale turbulence but also the saturation mechanism involving a dominant interaction with weakly damped zonal modes.…”

Section: Previous Work On Etg and The Collisionality Scalingmentioning

confidence: 99%

Collisionality scaling of the electron heat flux in ETG turbulence

Colyer¹,

Schekochihin²,

Parra³

et al. 2017

Plasma Phys. Control. Fusion

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In electrostatic simulations of MAST plasma at electron-gyroradius scales, using the local flux-tube gyrokinetic code GS2 with adiabatic ions, we find that the longtime saturated electron heat flux (the level most relevant to energy transport) decreases as the electron collisionality decreases. At early simulation times, the heat flux "quasisaturates" without any strong dependence on collisionality, and with the turbulence dominated by streamer-like radially elongated structures. However, the zonal fluctuation component continues to grow slowly until much later times, eventually leading to a new saturated state dominated by zonal modes and with the heat flux proportional to the collision rate, in approximate agreement with the experimentally observed collisionality scaling of the energy confinement in MAST. We outline an explanation of this effect based on a model of ETG turbulence dominated by zonal-nonzonal interactions and on an analytically derived scaling of the zonal-mode damping rate with the electron-ion collisionality. Improved energy confinement with decreasing collisionality is favourable towards the performance of future, hotter devices.

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“…While electron-scale isotropic eddies would imply negligible transport, numerical simulations of ETGs show radially elongated structures, known as ETG streamers [2], which by increasing the radial size of the turbulence could allow significant electron heat transport [3]. Indeed, from the experimental side, a correlation between the increase of the electron heat flux q e and the increase of high-k density fluctuations has been reported in [4][5][6][7][8]. Modelling plasmas featuring ETGs by means of Gyrokinetic (GK) [9] codes can give an insight on the impact that they have on the turbulent transport.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the role of electron temperature gradient modes in electron heat transport in TCV plasmas

et al. 2019

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Electron-scale micro-turbulence driven by the electron temperature gradient (ETG) instability have recently been shown to impact the electron heat transport in tokamaks. Given the relevance of these mechanisms for ITER scenarios, a new study has been carried out on the TCV tokamak at the Swiss Plasma Center, which is equipped with both ECH and NBI heating, allowing to investigate the relevance of ETG transport. Dedicated L-mode TCV discharges have been performed and the experimental measurements have been compared with gyrokinetic simulations. The results indicate that ETGs should contribute to electron heat transport from midradius to the edge when NBI and ECH are simultaneously applied, while the cases with pure ECH are dominated by ion-scale turbulence at mid-radius and show signs of possible ETG contribution only at outer radii.

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Evolution of ETG mode scale turbulence and anomalous electron transport in dynamic tokamak experiments

Cited by 21 publications

References 28 publications

Fast synthetic X-mode Doppler reflectometry diagnostics for the full-f global gyrokinetic modeling of the FT-2 tokamak

Fast synthetic X-mode Doppler reflectometry diagnostics for the full-f global gyrokinetic modeling of the FT-2 tokamak

Collisionality scaling of the electron heat flux in ETG turbulence

Investigation of the role of electron temperature gradient modes in electron heat transport in TCV plasmas

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