Radial profile of plasma potential with various biased electrode ring configurations in a toroidal plasma

Chaube, Nilima Rani; Jain, K. K.

doi:10.1063/1.871976

Cited by 5 publications

(4 citation statements)

References 15 publications

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“…Using these facts, a radial width of electrode about 5.12 mm (about 13.8ρ s ) has been taken for our 2D simulation. It is to be noted that the full poloidal extent of the probe has been taken into account as the nested poloidal magnetic flux surfaces charge each magnetic field line by the same potential in all poloidal locations [49]. We have also carried out the effect of the electrode biasing position in the radial direction in the edge region.…”

Section: Simulation Resultsmentioning

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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Section: Simulation Resultsmentioning

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 quasi-steady toroidal magnetic field of up to 0.1 T is produced for 1.2 s duration. The error vertical magnetic field estimated in our experimental set-up is around 3 × 10 −4 T at a toroidal magnetic field of 0.024 T, when no vertical magnetic field is applied [10]. The hot cathode discharge method is used to produce the plasma in the BETA machine.…”

Section: Experimental Set-up and Methodsmentioning

confidence: 99%

“…Several such devices exist across the globe and have provided immense wealth of interesting experimental findings. A series of experiments [5][6][7][8][9][10] on the study of low-frequency (LF) instabilities have been conducted in the toroidal device, BETA (basic experiment in toroidal assembly) [4]. During these experiments, it has been shown that magnetized low-β plasma embedded in a pure toroidal magnetic field is subjected to different classes of instabilities, depending on the plasma parameters.…”

Section: Introductionmentioning

confidence: 98%

Low-frequency fluctuations in a pure toroidal magnetized plasma

2009

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A magnetized, low-β plasma in pure toroidal configuration is formed and extensively studied with ion mass as control parameter. Xenon, krypton and argon plasmas are formed at a fixed toroidal magnetic field of 0.024 T, with a peak density of ∼10 11 cm −3 , ∼4 × 10 10 cm −3 and ∼2 × 10 10 cm −3 respectively. The experimental investigation of time-averaged plasma parameter reveals that their profiles remain insensitive to ion mass and suggests that saturated slab equilibrium is obtained. Low-frequency (LF) coherent fluctuations (ω < ω ci) are observed and identified as flute modes. Here ωci represents ion cyclotron frequency. Our results indicate that these modes get reduced with ion mass. The frequency of the fluctuating mode decreases with increase in the ion mass. Further, an attempt has been made to discuss the theory of flute modes to understand the relevance of some of our experimental observations.

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“…Moreover, some preliminary experiments performed in large and small devices Chiueh et al (1986) and Groebner et al (1990), and particularly those conducted in the toroidal device BETA by Chaube and Jain (1996) and Jain (1996), have shown that the application of radial electric fields can lead to a decrease in turbulence and an improvement in plasma confinement.…”

Section: Introductionmentioning

confidence: 99%