Gas-puff induced cold pulse propagation in ADITYA-U tokamak

Macwan, Tanmay; Raj, Harshita; Singh, Kaushlender; Dolui, Suman; Patel, Sharvil; Kumar, Ankit; Gautam, Pramila; Ghosh, Joydeep; Tanna, R.L.; Jadeja, K. A.; Patel, Kaushal; Kumar, Rohit; Aich, Suman; Panchal, V. K.; Nagora, Umesh; Chowdhuri, M. B.; Manchanda, R.; Yadava, Nandini; Dey, R.; Patel, Kiran; Raval, Jayesh; Pathak, S.K.; Gupta, Manoj Kumar; Tahiliani, Kumudni; Chattopadhyay, P. K.; Sen, Abhijit; Saxena, Y. C.; Pal, Rabindranath; Team, Aditya-U

doi:10.1088/1741-4326/ac189b

Cited by 10 publications

(20 citation statements)

References 48 publications

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“…It is quite well known that the decrease in positive radial electric field reduces the ion orbit loss. Also, as mentioned earlier, the loop voltage increases with the gas puff, which increases the Ware pinch [26]. Hence, the pinch is the most likely reason for the sharp density rise in our experiments.…”

Section: Gas-puff Induced Cold Pulse Propagationsupporting

confidence: 74%

“…Hard X-ray (HXR) emission are monitored using the NaI (Tl) scintillator detector and bolometer arrays are used for total radiated power measurements [25]. Langmuir probes are used for edge electron density, temperature, floating potential fluctuations measurements [26]. An infrared imaging camera is used for estimating the heat-load on the plasma peripherals and two fast visible imaging video cameras image the plasma column as described in [7].…”

Section: Aditya-u Operations and Experimental Progressmentioning

confidence: 99%

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Overview of recent experimental results from the ADITYA-U tokamak

Tanna¹,

Macwan²,

Ghosh³

et al. 2022

Nucl. Fusion

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Since the 2018 IAEA-FEC conference, in addition to expanding the parameter horizons of the ADITYA-U machine, emphasis has been given to dedicated experiments on inductively driven particle injection (IPI) for disruption studies, runaway electron (RE) dynamics and mitigation, plasma rotation reversal, radiative-improved modes using Ne and Ar injection, modulation of magneto–hydrodynamic modes, edge turbulence using periodic gas puffs and electrode biasing (E-B). Plasma parameters close to the design parameters of circular plasmas with H2 and D2 as fuel have been realized, and the shaped plasma operation has also been initiated. Consistent plasma discharges having I P ∼ 100–210 kA, t ∼ 300–400 ms, n e ∼ 3–6 × 1019 m−3, core T e ∼ 300–500 eV were achieved with a maximum B T of ∼1.5 T. The enhanced plasma parameters are the outcome of repeated cycles of baking (135 °C), followed by extensive wall conditioning, which includes pulsed glow discharge cleaning in H, He and Ar–H mixture, and lithiumization. A higher confinement time has been observed in D2 compared to H2 plasmas. Furthermore, shaped plasmas are attempted for the first time in ADITYA-U. A first of its kind inductively driven particle injection for disruption mitigation studies has been developed and operated. The injection of solid particles into the plasma core leads to a fast current quench. Two pulses of electron cyclotron resonance wave at 42 GHz are launched in a single discharge: one pulse is used for pre-ionization and the second for heating. In a novel approach, a positively biased electrode is used to confine REs after discharge termination. E-B is also used for controlling the rotation of drift-tearing modes by changing the plasma rotation. Cold pulse propagation and signatures of detachment are observed during the injection of short gas puffs. A correlation between the plasma toroidal rotation and the total radiated power has been observed with neon gas injection-induced improved confinement modes.

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Section: Gas-puff Induced Cold Pulse Propagationsupporting

confidence: 74%

Section: Aditya-u Operations and Experimental Progressmentioning

confidence: 99%

Overview of recent experimental results from the ADITYA-U tokamak

Tanna¹,

Macwan²,

Ghosh³

et al. 2022

Nucl. Fusion

Self Cite

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show abstract

“…The ADITYA-U tokamak [12,25,26] which has recently been upgraded to divertor configuration [26], is small in size and well suited for the investigation of micro-instabilities in the presence of density and temperature gradients. The gradient in the plasma profile can drive several temperature and density gradient instabilities, such as ITG [6,[27][28][29][30], trapped electron mode (TEM) [31,32], universal drift modes [33,34] etc which are electrostatic in nature.…”

Section: Linear Gyrokinetic Simulations With Orb5 and Glogystomentioning

confidence: 99%

“…Hence, in this work, we perform global linear and nonlinear electrostatic simulation studies of the conventional (ITGs) mode and SWITGs, which are both unstable, resulting in a multi-scale gyrokinetic transport, for profiles and parameters relevant to the ADITYA-U tokamak. Conventionally, in ADITYA-U discharges, it is observed that the electron temperature is almost three times greater than the ion temperature [25]. In the presence of external auxiliary heating mechanisms, it is expected that the ion temperature would become comparable to the electron temperature, i.e, T i = T e .…”

Section: Linear Gyrokinetic Simulations With Orb5 and Glogystomentioning

confidence: 99%

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Gyrokinetic simulation of short wavelength ion temperature gradient instabilities in the ADITYA-U tokamak

et al. 2023

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In this work, linear and nonlinear collisionless electrostatic simulation studies of the standard and short wavelength ion temperature gradient mode (SWITG) for experimental profiles and parameters of ADITYA-U tokamak are performed using the linear global eigenvalue gyrokinetic code GLOGYSTO and the nonlinear global gyrokinetic PIC code ORB5. All simulations are carried out with non-adiabatic ions and adiabatic electrons. The ADITYA-U tokamak which has recently been upgraded to divertor configuration, is small in size and well suited for investigation of micro-instabilities in the presence of density and temperature gradients. Due to steep density and temperature gradients, simulation shows that SWITG mode naturally exists along with the standard ITG mode in ADITYA-U. In this work, the experimental shot# 33536 of ADITYA-U tokamak is considered as a reference. Good agreement in growth rate and real frequency values between GLOGYSTO and ORB5 with variations of less than 25%. Two maxima of growth rate versus mode number are obtained, the first around kθ ρs ≃ 0.4 is the standard ITG, the second around kθ ρs ≃ 1.2 is the SWITG. Additionally, using linear stability analysis, it is observed that the SWITGs are suppressed for low values of R0 /LT i.e., only the standard ITG mode remains unstable. For the ADITYA-U tokamak, nonlinear global simulations with ORB5 are also carried out. Nonlinearly, SWITG dominating case results are compared with the conventional ITG case, where SWITG is relatively suppressed. The nonlinear contribution of the SWITG mode to the total thermal ion heat transport is found to be minimal due to an increased zonal flow shearing effect on the SWITG mode suppression, even though it may be linearly more unstable than the conventional long wavelength (kθ ρs < 1) ITG mode.

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Local transport dynamics of cold pulses in tokamak plasmas

Rodriguez-Fernandez

Angioni

White

2022

Rev. Mod. Plasma Phys.

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For over two decades, our fundamental understanding of energy transport dynamics in the core of tokamak plasmas had been challenged by the striking observation of temperature perturbation reversals following the injection of cold pulses at the plasma edge. These phenomena were first discovered by Gentle et al. (Phys. Rev. Lett. 74(18):3620–3623, 1995) in 1995 and had long been suggested to be evidence of nonlocal transport effects. In recent years, a new explanation to these phenomena has emerged, fully consistent with the theory of turbulent transport in magnetized plasmas and in remarkable agreement with experiment. This article reviews the experimental observation of temperature reversals in tokamak plasmas and presents the explanation based on local transport physics.

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Gas-puff induced cold pulse propagation in ADITYA-U tokamak

Cited by 10 publications

References 48 publications

Overview of recent experimental results from the ADITYA-U tokamak

Overview of recent experimental results from the ADITYA-U tokamak

Gyrokinetic simulation of short wavelength ion temperature gradient instabilities in the ADITYA-U tokamak

Local transport dynamics of cold pulses in tokamak plasmas

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