Ultra lowq a discharge experiments in the SINP tokamak

Iyengar, A. N. Sekar; Majumdar, S. K.; Basu, J. K.; Paul, R. K.; Pal, Rabindranath; Chowdhury, Satyajit

doi:10.1007/bf02857507

Cited by 8 publications

(6 citation statements)

References 18 publications

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“…Using this and from the definition of q a (q a 2πa 2 p B t µ 0 RI p ) (I p Í p T q a µ T q a İ p T q a ), we have obtained a general relation for T q a (the time to cross the rational q a values) [3] T q a B t a 2 p 2π µ 0 Rq aİ p 1 (2) where B t is the toroidal field, a and R are the minor and major radii respectively. Now, for q a 2 one can get the relation between T 2 B t andİ 1 p as given in [13].…”

Section: Experiments and Results Related To The Accessibility Of The mentioning

confidence: 95%

“…Factors such as the low toroidal field and high gas filling pressure also have important contributions. Some other factors like presence of the conducting shell [2,3], surrounding the vacuum vessel, may also have some contribution in the setting up process. Loop voltage, plasma current (I p ) and the edge safety factor q a for a typical ULQ discharge are shown in figures 1a, 1b and 1c respectively.…”

Section: Experiments and Results Related To The Accessibility Of The mentioning

confidence: 98%

“…Details of this tokamak and the experiments have already been published in various works [1][2][3][4]12]. The low q a discharges have been obtained in a specific parameter space as follows: limiter radius (a l ) from 0.065 m to 0.045 m, B t from 0.44 T to 0.33 T, secondary voltage from 60 V to 90 V and gas filling pressure (P fill ) 3 0 ¢ 10 4 torr.…”

Section: Experiments and Results Related To The Accessibility Of The mentioning

confidence: 99%

“…Discharges with a wide range of edge safety factors (0 q a 5 0) [1][2][3][4] have been obtained in the SINP tokamak. This range includes the normal q a (NQ), very low q a (VLQ) and ultra low q a (ULQ) discharges.…”

Section: Introductionmentioning

confidence: 99%

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Investigations of low q a discharges in the SINP tokamak

et al. 2002

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Low edge safety factor discharges including very low q a (1 q a 2) and ultra low q a (0 q a 1) have been obtained in the SINP tokamak. It has been observed that accessibility of these discharges depends crucially on the fast rate of plasma current rise. Several interesting results in terms of different time scales like T q a , τ R etc have been obtained using a set of softwares developed at SINP. From fluctuation analysis of the external magnetic probe data it has been found that MHD instabilities m 1, n 1 and m 2, n 1 etc. play major role in the evolution of these discharges. To investigate the internal details of these discharges, an internal magnetic probe system has been developed using which current density j φ and other related parameters have been estimated. By carrying out a resistive stability analysis, evidence of the above-mentioned MHD instabilities have again been found. The physical processes lying behind the accessibility and evolution of the low q a discharges have been thoroughly investigated.

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Section: Experiments and Results Related To The Accessibility Of The mentioning

confidence: 95%

Section: Experiments and Results Related To The Accessibility Of The mentioning

confidence: 98%

Section: Experiments and Results Related To The Accessibility Of The mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Investigations of low q a discharges in the SINP tokamak

et al. 2002

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“…< 2 and q+,. < 1) have been setup in the SINP tokamak [4,5], and it is seen that the current rise phase plays at~ important role in tile accessibility and evolution of these discharges [5][6][7]. In this paper, the principal airn of study was to simulate the current density prol{le evolution in the rising phase of tile low % discharges obtained experimeataUy in the SINP tokamak.…”

Section: Introductionmentioning

confidence: 99%

Stability-transport modeling of the SINP tokamak discharges

et al. 2001

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A one-dimensional stability transport code has been developed to simulate the evolution of tokamak plasma discharges. Explick finite-difference methods have been used to follow the temporal evolution of' dre electron temperature equation. The poloidal field diffusion equation has been solved at every time step. The effects of MHD instabilities have been incorporated by soh'ing equations for MHD mixing and tearing modes as and when required. The code has been applied to follow the evolution of tokamak plasma discharges obtained in the Saha institute of Nuclear Physics (SINP) tokamak, From these simulations, we have been able to identify the possible models of thermal conductivity, diffusion and impurity contents in these discharges. Effects of different MHD modes have been estimated. It has been found that in low q~ discharge 't~'~ --t, ~l = 1 and m = 2, ~ = 1 modes play n-tajor role in discharge evo[u6on. These modes are found to result in the positive jump in tSe loop voltage whicla w;ts also observed in the experiments, Hollow current density profile j,~ and negative shear ill the q profile have also been found in the rising phase of a discharge.

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Setup for potential bias experiments on the Saha Institute of Nuclear Physics tokamak

Ghosh

Pal

Chattopadhyay

1999

Review of Scientific Instruments

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An experimental setup for studying the influence of the radial electric field on very low qa plasma on the Saha Institute of Nuclear Physics tokamak is presented. A high current, high voltage pulsed power supply, using a semiconductor controlled rectifier (SCR) as a dc switch is developed and used to bias a tungsten electrode inserted inside the plasma. The electrode’s exposed length and its position inside the plasma are controlled by a double bellows assembly to optimize the electrode-exposed length. We show that using the force commutation method to turn the SCR off to get the power pulse desired has good potential for carrying out similar kinds of studies, especially in a low budget small tokamak.

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Ultra lowq a discharge experiments in the SINP tokamak

Cited by 8 publications

References 18 publications

Investigations of low q a discharges in the SINP tokamak

Investigations of low q a discharges in the SINP tokamak

Stability-transport modeling of the SINP tokamak discharges

Setup for potential bias experiments on the Saha Institute of Nuclear Physics tokamak

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