Long-distance correlations in TCABR biasing experiments

Kuznetsov, Yu.K.; Nascimento, I. C.; Silva, Carlos; Figueiredo, H.; Guimarães-Filho, Z. O.; Caldas, Iberê L.; Galvão, R. M. O.; Severo, J. H. F.; Toufen, D. L.; Ruchko, L.; Elfimov, A. G.; Elizondo, Juan Iraburu; Sá, W.P. de; Usuriaga, O. C.; Sanada, Edson Kenzo; Melnikov, A. V.; Gryaznevich, M.; Alonso, M. P.; Reis, A. Pires dos; Machida, Munemasa; Trembach, D.; Germano, Társis M; Narayanan, R.; Ghoranneviss, M.; Arvin, R.; Mohammadi, S.; Tekieh, S.R.S.; Borges, Felipe Azevedo; Bellintani, V.; Canal, G. P.; Duarte, P.; Castro, R M; Vorobyov, G. M.; Mizintseva, Maria A.; Moiseenko, V. E.; Nascimento, Fellype do; Ronchi, G.; Schmutzler, L. M. F.

doi:10.1088/0029-5515/52/6/063004

Cited by 14 publications

(9 citation statements)

References 20 publications

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“…This, in turn, drives poloidal rotation and so generates a sheared radial electric field, which then regulates edge turbulence and transport [17]. Suppression of edge turbulence and transport by biased electrode-driven shear flow has been observed previously on J-TEXT and other devices [32][33][34][35]. This improved confinement regime is sometimes referred to as the 'biased H-mode' state.…”

Section: Introductionmentioning

confidence: 84%

Electrode biasing maintains the edge shear layer at high density in the J-TEXT tokamak

Diamond

Long

et al. 2022

Nucl. Fusion

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Collapse of the edge flow shear as the line-averaged density approaches the Greenwald density limit has been observed as a precursor to the enhanced edge particle flux characteristic of proximity to the density limit regime. Here, we report the use of a biased electrode to sustain the edge shear layer in high density discharges, in which the shear layer would otherwise collapse. A stable increase in line-averaged density is observed along with a strong increase in edge density. These experiments were carried out on the J-TEXT tokamak. The Reynolds stress at the edge is enhanced, and the zonal flow sustained, while density perturbation levels, the flux of turbulence internal energy (i.e., turbulence spreading), and particle and heat flux all decrease significantly. Electron adiabaticity increases, and bias voltage modulation experiments show that an increase in the edge shear leads the increase in adiabaticity. These results suggest that external edge E×B flow shear drive may be of interest for sustaining edge plasma states at high density, and support the hypothesis that collapse of the edge shear layer triggers the onset of the strong transport and turbulence characteristic of the density limit regime.

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Section: Introductionmentioning

confidence: 84%

Electrode biasing maintains the edge shear layer at high density in the J-TEXT tokamak

Diamond

Long

et al. 2022

Nucl. Fusion

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“…Several authors have studied the effect of biasing in the edge or SOL region. The biasing in these regions can be done in several ways e.g., divertor biasing [8][9][10][11][12], limiter biasing [13][14][15][16], emissive probe biasing [17,18], and electrode biasing [19][20][21][22][23][24][25][26][27][28]. An experiment carried out on the ISTTOK tokamak has shown [29] that electrode biasing in the edge region is more effective in comparison to limiter biasing.…”

Section: Introductionmentioning

confidence: 99%

Edge biasing and its impact on the edge and SOL turbulence

Shankar¹,

Bisai²,

Raj³

et al. 2022

Nucl. Fusion

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A theoretical study is made of the effect of edge biasing on the dynamics of the interchange turbulence in the edge and scrape-off layer (SOL) regions. A linear analysis of a set of model fluid equations shows that biasing stabilizes the small ky modes. The model equations are next solved numerically, using the BOUT++ framework, to explore the nonlinear dynamics in the presence of positive or negative bias and compared to results in the absence of bias. Positive biasing is found to lead to a larger increment in plasma density and temperature as compared to negative biasing. It is further observed that cross-correlation between density and poloidal electric field at different radial positions decreases for positive biasing and in the case of negative biasing it is almost similar to that of no biasing. Plasma density and poloidal electric field fluctuations have been investigated which show that the density fluctuations increase (decrease) for positive (negative) biasing but the radially outward flux for these biasing cases always decreases mainly due to the decrease of cross-correlation between density and poloidal electric field fluctuations.

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“…as sondas são separadas na direção toroidal, mas mantidas na mesma posição radial, e a correlação entre os sinais calculada como na Ref. [53]. Isso signica que não só verica-se a presença de elétrons supratérmicos, mas que as correlações de longo alcance são subjacentes ao modo H. Na Fig.…”

Section: Distribuições Não-maxwellianas E Estatística Não-extensivaunclassified

Teoria cinética não extensiva e transporte colisional em plasmas magnetizados

Oliveira¹

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Long-distance correlations in TCABR biasing experiments

Cited by 14 publications

References 20 publications

Electrode biasing maintains the edge shear layer at high density in the J-TEXT tokamak

Electrode biasing maintains the edge shear layer at high density in the J-TEXT tokamak

Edge biasing and its impact on the edge and SOL turbulence

Teoria cinética não extensiva e transporte colisional em plasmas magnetizados

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