Non-local component of electron heat transport in TFTR

Kissick, M; Callen, J. D.; Fredrickson, E. D.; Janos, A.; Taylor, G.

doi:10.1088/0029-5515/36/12/i09

Cited by 55 publications

(111 citation statements)

References 21 publications

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“…Following the edge cooling, there was a rapid increase of the core electron temperature, on a time scale (∼5 ms) faster than the diffusive time. This effect is suggestive of a short-lived internal transport barrier (ITB), triggered by the sudden increase of the edge temperature gradient, which can be modeled with an abrupt drop in the core electron thermal conductivity [19,20,21,23,24,25,27], and which persists for the duration of the edge cooling (∼30 ms). A model for this transient increase in electron heat transport (a drop in thermal conductivity) is shown in Fig.3, with a 25% drop in χ e near r/a = 0.3 (solid to dash-dot lines).…”

Section: Methodsmentioning

confidence: 99%

Non-local heat transport, rotation reversals and up/down impurity density asymmetries in Alcator C-Mod ohmic L-mode plasmas

Rice¹,

Gao²,

Reinke³

et al. 2013

Nucl. Fusion

155

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Several seemingly unrelated effects in Alcator C-Mod Ohmic L-mode plasmas are shown to be closely connected: non-local heat transport, core toroidal rotation reversals, energy confinement saturation and up/down impurity density asymmetries. These phenomena all abruptly transform at a critical value of the collisionality. At low densities in the linear Ohmic confinement regime, with collisionality ν * ≤ 0.35 (evaluated inside of the q=3/2 surface), heat transport exhibits non-local behavior, core toroidal rotation is directed co-current, edge impurity density profiles are up/down symmetric and a turbulent feature in core density fluctuations with k θ up to 15 cm −1 (k θ ρ s ∼ 1) is present. At high density/collisionality with saturated Ohmic confinement, electron thermal transport is diffusive, core rotation is in the counter-current direction, edge impurity density profiles are up/down asymmetric and the high k θ turbulent feature is absent. The rotation reversal stagnation point (just inside of the q=3/2 surface) coincides with the non-local electron temperature profile inversion radius. All of these observations can be unified in a model with trapped electron mode prevalence at low collisionality and ion temperature gradient mode domination at high collisionality.

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Section: Methodsmentioning

confidence: 99%

Non-local heat transport, rotation reversals and up/down impurity density asymmetries in Alcator C-Mod ohmic L-mode plasmas

Rice¹,

Gao²,

Reinke³

et al. 2013

Nucl. Fusion

155

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“…(II) The sign of the perturbation reverses, i.e., a cooling at the edge results in heating of the core, and vice versa. Such evidence has accumulated through dedicated experiments, including edge cooling by laser blowoff (LBO) of impurities, pellets, radio frequency (RF) heating, and plasma current ramping, performed in several devices, including tokamaks and stellarators [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. The ubiquity of these phenomena calls naturally for some common fundamental physics basis.…”

mentioning

confidence: 99%

“…All the parameters (A, r S , w S , τ, χ n , χ p ) not a priori known are varied until a good match between the numerical T and experimental traces is obtained. We carried out this exercise for data from the experiments TEXT [3], TFTR [6], RTP [7], ASDEX-Upgrade [8], Tore Supra [9], LHD [14], and JET [17]. Extensive results are given in the Supplemental Material [23], while we provide details here for a few.…”

mentioning

confidence: 99%

Alfvénic Propagation: A Key to Nonlocal Effects in Magnetized Plasmas

Sattin¹,

Escande

2014

Phys. Rev. Lett.

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A long-standing puzzle in fusion research comes from experiments where a sudden peripheral electron temperature perturbation is accompanied by an almost simultaneous opposite change in central temperature, in a way incompatible with local transport models. This Letter shows that these experiments and similar ones are fairly well quantitatively reproduced, when induction effects are incorporated in the total plasma response, alongside standard local diffusive transport, as suggested in earlier work [Plasma Phys. Controlled Fusion 54, 124036 (2012).

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“…Many kinds of peculiar non-local transport phenomena have been reported by both tokamak and helical experiments [1][2][3][4][5][6]. For example, an edge cooling perturbation can cause the core electron temperature to start increasing under certain conditions.…”

Section: Introductionmentioning

confidence: 99%

Observation of Electron-Temperature Fluctuations Triggered by Supersonic Gas Puffing in the LHD

Murakami

Miyazawa

Yasui

et al. 2011

Plasma and Fusion Research

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Non-local transport and electron temperature fluctuations triggered by supersonic gas puffing (SSGP) in high-temperature helical plasmas in the Large Helical Device (LHD) are reported. After a short-pulse SSGP, the core electron temperature increased while the edge electron temperature decreased. SSGP triggered a longer core temperature increase than that triggered by a small impurity pellet injection. The temperature profile, which was relatively flat inside the half minor radius before SSGP, became parabolic after non-local transport was triggered. Fluctuations were excited in the electron temperature signals around the half minor radius. The frequency of these fluctuations increased from ∼ 400 Hz to ∼ 1 kHz within ∼ 0.1 s and the amplitude decreased correspondingly. The temperature fluctuations inside and outside of the half minor radius had opposite phases. Magnetic fluctuations resonating near the half minor radius were observed simultaneously with the electron temperature fluctuations.

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Non-local component of electron heat transport in TFTR

Cited by 55 publications

References 21 publications

Non-local heat transport, rotation reversals and up/down impurity density asymmetries in Alcator C-Mod ohmic L-mode plasmas

Non-local heat transport, rotation reversals and up/down impurity density asymmetries in Alcator C-Mod ohmic L-mode plasmas

Alfvénic Propagation: A Key to Nonlocal Effects in Magnetized Plasmas

Observation of Electron-Temperature Fluctuations Triggered by Supersonic Gas Puffing in the LHD

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