Diamagnetic flux measurement in Aditya tokamak

Kumar, Sameer; Jha, Ratneshwar; Lal, Praveen; Hansaliya, Chandresh; Gopalkrishna, M. V.; Kulkarni, Sanjay; Mishra, K.

doi:10.1063/1.3514092

Cited by 13 publications

(15 citation statements)

References 16 publications

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“…This is derived by substitution of ( 44) and ( 45) into definition (10). Since the expansion in d with 2 |d| << 1 has been used on the way to (51), the difference between α m and α L cannot be large in our model. Nevertheless, the formula is consistent with the discovery in computations in [4] that α m ̸ = α L for the plasma with a rapid variation of ellipticity near the boundary.…”

Section: Discussion Of Analytical Resultsmentioning

confidence: 99%

Theoretically assisted and empirical scalings in the problem of determination of internal inductance in tokamaks

Pustovitov

2023

Plasma Phys. Control. Fusion

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The problem of inferring the internal inductance Li from external magnetic measurements in tokamaks is considered. It was practically resolved in JET (Barana O et al 2002 Plasma Phys. Control. Fusion 44 2271), but several questions remain to be addressed before extrapolation of that method on other tokamaks. These naturally arise because of the integral nature of Li determined by unknown distribution of the magnetic field inside the plasma. Without universal solutions, the quality of approximations should be examined along with potential experimental enforcements of the existing procedures. This is the main goal of the study that is fully analytical. Several relevant quantities are calculated for the large-aspect-ratio plasma with elliptical shifted magnetic surfaces. Usually the plasma elongation K is mentioned as a key factor in the task. Here it is explicitly shown that not only K , but its radial derivative too plays a role. The latter parameter did not appear in the JET scaling and in the accompanying discussions. It is also shown that the K-dependent term representing there the first iteration actually brings a systematic error. Therefore, several improvements to that scaling can be proposed. The study is based on the use of virial relations for the toroidal axisymmetric configurations.

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Section: Discussion Of Analytical Resultsmentioning

confidence: 99%

Theoretically assisted and empirical scalings in the problem of determination of internal inductance in tokamaks

Pustovitov

2023

Plasma Phys. Control. Fusion

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“…Similary, the loop voltage is measured using four flux loops, each containing a single-turn copper wire, placed at four different locations on the vacuum vessel. The plasma stored energy is measured using compensated diamagnetic loops 42 . The edge-plasma diagnostics consist of sets of Langmuir probes placed along the poloidal periphery at different toroidal locations.…”

Section: Methodsmentioning

confidence: 99%

Role of pinch in Argon impurity transport in Ohmic discharges of Aditya-U Tokamak

Shah,

Ghosh,

Patel

et al. 2023

Preprint

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We present experimental results of the trace argon impurity puffing in the Ohmic plasmas of Aditya-U tokamak performed to study the argon transport behaviour. Argon line emissions in visible and Vacuum Ultra Violet (VUV) spectral ranges arising from the plasma edge and core respectively are measured simultaneously. During the experiments, space resolved brightness profile of Ar1+ line emissions at 472.68 nm (3p44s 2P1.5 - 3p44p 2D1.5), 473.59 nm (3p44s 4P2.5 - 3p44p 4P1.5), 476.48 nm (3p44s 2P0.5 - 3p44p 2P1.5), 480.60 nm (3p44s 4P2.5 - 3p44p 4P2.5) are recorded using a high resolution visible spectrometer. Also, a VUV spectrometer has been used to simultaneously observe Ar13+ line emission at 18.79 nm (2s22p 2P1.5 - 2s2p2 2P1.5) and Ar14+ line emission at 22.11 nm (2s2 1S0 - 2s2p 1P1). The diffusivity and convective velocity of Ar are obtained by comparing the measured radial emissivity profile of Ar1+ emission and the line intensity ratio of Ar13+ and Ar14+ ions, with those simulated using the impurity transport code, STRAHL. Argon diffusivities ~ 12 m2/s and ~ 0.3 m2/s have been observed in the edge (ρ > 0.85) and core region of the Aditya-U, respectively. The diffusivity values both in the edge and core region are found to be higher than the neo-classical values suggesting that the argon impurity transport is mainly anomalous in the Aditya-U tokamak. Also, an inward pinch of ~ 10 m/s mainly driven by Ware pinch is required to match the measured and simulated data. The measured peaked profile of Ar density suggests impurity accumulation in these discharges.

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“…The total radiated power is measured using the AXUV bolometer [22] and plasma stored energy is measured using a diamagnetic loop [23]. The MHD oscillations are measured by a garland of 16 Mirnov coils distributed at equal angular separations in the poloidal direction at a single toroidal location [24].…”

Section: Methodsmentioning

confidence: 99%

Overview of recent experimental results from the Aditya tokamak

Tanna¹,

Ghosh²,

Chattopadhyay³

et al. 2017

Nucl. Fusion

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Several experiments, related to controlled thermonuclear fusion research and highly relevant for large size tokamaks, including ITER, have been carried out in ADITYA, an ohmically heated circular limiter tokamak. Repeatable plasma discharges of a maximum plasma current of ~160 kA and discharge duration beyond ~250 ms with a plasma current flattop duration of ~140 ms have been obtained for the first time in ADITYA. The reproducibility of the discharge reproducibility has been improved considerably with lithium wall conditioning, and improved plasma discharges are obtained by precisely controlling the position of the plasma. In these discharges, chord-averaged electron density ~3.0–4.0 × 1019 m−3 using multiple hydrogen gas puffs, with a temperature of the order of ~500–700 eV, have been achieved. Novel experiments related to disruption control are carried out and disruptions, induced by hydrogen gas puffing, are successfully mitigated using the biased electrode and ion cyclotron resonance pulse techniques. Runaway electrons are successfully mitigated by applying a short local vertical field (LVF) pulse. A thorough disruption database has been generated by identifying the different categories of disruption. Detailed analysis of several hundred disrupted discharges showed that the current quench time is inversely proportional to the q edge. Apart from this, for volt–sec recovery during the plasma formation phase, low loop voltage start-up and current ramp-up experiments have been carried out using electron cyclotron resonance heating (ECRH). Successful recovery of volt–sec leads to the achievement of longer plasma discharge durations. In addition, the neon gas puff assisted radiative improved confinement mode has also been achieved in ADITYA. All of the above mentioned experiments will be discussed in this paper.

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Diamagnetic flux measurement in Aditya tokamak

Cited by 13 publications

References 16 publications

Theoretically assisted and empirical scalings in the problem of determination of internal inductance in tokamaks

Theoretically assisted and empirical scalings in the problem of determination of internal inductance in tokamaks

Role of pinch in Argon impurity transport in Ohmic discharges of Aditya-U Tokamak

Overview of recent experimental results from the Aditya tokamak

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