Runaway-loss induced negative and positive loop voltage spikes in the Aditya Tokamak

Paradkar, Bhooshan S.; Ghosh, Joydeep; Chattopadhyay, P. K.; Tanna, R.L.; Raju, D.; Bhatt, S. B.; Rao, C. V. S.; Joisa, Sankar; Banerjee, Santanu; Manchanda, R.; Gupta, C.N.; Saxena, Y. C.; Team, Aditya

doi:10.1063/1.3474949

Cited by 17 publications

(19 citation statements)

References 15 publications

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“…First, radial density profiles of the ground state of each charge state of argon are obtained from the STRAHL code using the measured radial profiles of electron density and reconstructed radial profile of electron temperature based on the measured core and edge electron temperature 52 . The radial profiles of electron density and temperature used in the STRAHL code are shown in figure 8 as a function of normalized plasma minor radius ρ (= r / a, where 'a' is the limiter radius).…”

Section: Methods Of Argon Transport Analysismentioning

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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Section: Methods Of Argon Transport Analysismentioning

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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“…where S, α, and C are the reaction rate coefficients for ionization, recombination (radiative and di-electronic), and charge exchange, respectively. The required electron density profile is taken from the seven-channel microwave interferometer diagnostics and the radial profile was obtained from the chord integrated profile measurement using Abel inversion [21]. As the electron temperature is available only for the core and the edge regions of the plasma, its radial profile was generated using the following equation:…”

Section: Modeling Of the O 4+ Emissivity Profilementioning

confidence: 99%

Evaluation of an Oxygen Transport Coefficient in the Aditya Tokamak Using the Radial Profile of O4+ Emissivity and the Importance of Atomic Data Used Therein

Chowdhuri

Ghosh

Dey

et al. 2019

Atoms

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Oxygen impurity transport in the typical discharges of the Aditya tokamak was investigated using emissivity radial profile of emissivity of the spectral line (2p3p 3D3–2p3d 3F4) at 650.024 nm from the Be-like oxygen ion. This O4+ spectral line was recorded using a 1.0 m multi-track spectrometer capable of simultaneous measurements from eight lines of sight passing through the plasma. The oxygen transport coefficients were determined by reproducing the experimentally measured emissivity profiles of O4+, using a one-dimensional impurity transport code, STRAHL, and photon emissivity coefficient (PEC) belonging to that transition. The PEC values were obtained from both ADAS and NIFS atomic databases. Using both the databases, much higher values of diffusion coefficients compared to the neo-classical values were observed in both high and low magnetic field edge regions of typical Aditya tokamak Ohmic plasma. Although, almost similar profiles of diffusion coefficients were obtained using PEC values from both databases, the magnitude differs considerably. The maximum values of diffusion coefficients in the plasma edge at low field side of tokamak were ~45 and ~25 m2·s−1 when modeling was done using the ADAS and NIFS databases, respectively. Further analysis on the atomic data used in the calculation indicates that the difference in diffusion coefficients is mainly related to the variation in the values of atomic data of the two databases.

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“…It is noticed that the fitting error is less than 5%. Similarly, the radial profile of temperature is reconstructed after using Equation (3), where the measured values are used at the plasma center (T e,0 ) (from soft x-ray) and at the plasma edge (T e,a ) (from Langmuir probe and spectroscopy) [14,16,20]. The implementation of the DEGAS2 code and the details of the input parameters are described in [12,13], only a brief description is given here.…”

Section: Degas2 Code and Its Input Parametersmentioning

confidence: 99%

Modeling of the Hα Emission from ADITYA Tokamak Plasmas

Dey

Chowdhuri

Ghosh

et al. 2019

Atoms

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The spatial profile of Hα spectrum is regularly measured using a high-resolution multi-track spectrometer in ADITYA tokamak to study the neutral particle behavior. The Monte Carlo neutral particle transport code DEGAS2 is used to model the experimental Hα spectral emissions. Through the modeling of the spectral line profile of Hα, it is found that the neutral hydrogen, which is produced from molecular hydrogen and molecular hydrogen ion dissociation processes contributes 56% to the total Hα emission, and the atoms which are produced from charge-exchange process have 30% contribution. Furthermore, the experimentally measured spatial profile of chord integrated brightness was modeled for the two plasma discharges having relatively high and low density to understand the neutral particle penetration. The presence of neutrals inside the core region of the ADITYA tokamak is mainly due to the charge-exchange process. Furthermore, it is observed that neutral particle penetration is lower in higher density discharge.

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Runaway-loss induced negative and positive loop voltage spikes in the Aditya Tokamak

Cited by 17 publications

References 15 publications

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

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

Evaluation of an Oxygen Transport Coefficient in the Aditya Tokamak Using the Radial Profile of O4+ Emissivity and the Importance of Atomic Data Used Therein

Modeling of the Hα Emission from ADITYA Tokamak Plasmas

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