Tanmay Macwan
A5035004791- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Particle accelerators and beam dynamics
- Fusion materials and technologies
- Laser-Plasma Interactions and Diagnostics
- Nuclear reactor physics and engineering
- Plasma Diagnostics and Applications
- Atomic and Subatomic Physics Research
- Solar and Space Plasma Dynamics
- Nuclear Engineering Thermal-Hydraulics
- Power System Optimization and Stability
- High voltage insulation and dielectric phenomena
- Nuclear Materials and Properties
- Thermal Analysis in Power Transmission
- earthquake and tectonic studies
- Magnetic Field Sensors Techniques
- Radiation Detection and Scintillator Technologies
Institute for Plasma Research
2019-2024
University of California, Los Angeles
2022-2024
Homi Bhabha National Institute
2019-2024
UCLA Health
2024
Abstract The objectives of NSTX-U research are to reinforce the advantages STs while addressing challenges. To extend confinement physics low- A , high beta plasmas lower collisionality levels, understanding transport mechanisms that set performance and pedestal profiles is being advanced through gyrokinetic simulations, reduced model development, comparison NSTX experiment, as well improved simulation RF heating. develop stable non-inductive scenarios needed for steady-state operation,...
We use a new gyrokinetic threshold model to predict bifurcation in tokamak pedestal width-height scalings that depends strongly on plasma shaping and aspect-ratio. The arises from the first second stability properties of kinetic-ballooning-modes yields wide narrow branches, expanding space accessible widths heights. branch offers potential for edge-localized-mode-free pedestals with high core pressure. For negative triangularity, low-aspect-ratio configurations are predicted give steeper...
Abstract A gyrokinetic threshold model for pedestal width–height scaling prediction is applied to multiple devices. shaping and aspect ratio scan performed on National Spherical Torus Experiment (NSTX) equilibria, finding <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi mathvariant="normal">Δ</mml:mi> <mml:mi>ped</mml:mi> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>0.92</mml:mn> <mml:msup> <mml:mi>A</mml:mi>...
The first Indian tokamak, ADITYA, operated for over two decades with a circular poloidal limiter, has been upgraded to tokamak named ADITYA Upgrade (ADITYA-U) attain shaped-plasma operations an open divertor in single and double-null configurations. Experimental research using ADITYA-U made significant progress since the last FEC 2016. After installation of plasma facing component standard diagnostics ADITYA-U, Phase-I were initiated December 2016 graphite toroidal belt limiter. Ohmically...
Experiments on ADITYA-U tokamak show a marked enhancement in the sawtooth period by application of short gas puffs fuel that cause modification radial density profile. A consequent suppression trapped electron modes (TEMs) then leads to an increase core temperature. This slows down heat propagation following crash, causing delay achieving critical temperature gradient inside q = 1 surface required for next crash happen. The overall scenario has strong similarities with behavior under...
This article reports the development of a versatile high-speed reciprocating drive system (HRDS) with interchangeable probe heads to characterize edge plasma region ADITYA-U tokamak. consisting Langmuir and magnetic heads, is designed, fabricated, installed, operated for studying extent fuel/impurity gas propagation its influence on dynamics in far-edge inside last closed flux surface (LCFS). The HRDS driven by highly accurate, easy-to-control, dynamic, brushless, permanently excited...
The 2-D edge plasma fluid transport code, UEDGE has been used to simulate the region of circular limiter plasmas ADITYA-U for modelling measured electron density profile. geometry introduced in which is primarily developed and divertor configuration. computational mesh defining generated by a routine in-house, successfully integrated with code parameters ADITYA-U. radial profiles scrape-off layer (SOL) density, ne temperature are obtained from simulations model profile using Langmuir probe...
Abstract Since the 2018 IAEA-FEC conference, in addition to expanding parameter horizons of ADITYA-U machine, emphasis has been given 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 Ar injection, modulation magneto–hydrodynamic modes, edge turbulence periodic gas puffs electrode biasing (E-B). Plasma parameters close design circular plasmas...
Abstract A first-of-its-kind, inductively driven micro-particle (Pellet) accelerator and injector have been developed operated successfully in ADITYA-U circular plasma operations, which may ably address the critical need for a suitable disruption control mechanism ITER future tokamak. The device combines principles of electromagnetic induction, pulse power technology, impact, fracture dynamics. It is designed to operate variety environments, including atmospheric pressure ultra-high vacuum....
An impurity ion toroidal rotation profile has been observed in the ohmic discharges of Aditya-U tokamak from Doppler-shifted passive charge exchange line emission C5+ at 529 nm. The monitored using a space-resolved visible spectroscopy diagnostic consisting 1 m multi-track spectrometer coupled with device (CCD) detector. In typical central chord-averaged electron density ≲2.5 × 1019 m−3, maximum velocity plasma core is found to be −20 km s−1 counter-current direction. Reversal for high ~5...
Abstract Global gyrokinetic simulations of the electrostatic microturbulence driven by pressure gradients thermal ions and electrons are carried out for ADITYA-U tokamak geometry using its experimental plasma profiles with collisional effects. The dominant instability is trapped electron mode (TEM) based on linear eigenmode structure propagation in diamagnetic direction. Collisional effects suppress turbulence transport to a certain extent. Zonal flow not playing critical role TEM...
Enhanced Dα H-mode (EDA H-mode), an ELM-free regime, and the concomitant quasi-coherent mode (QCM) are explored in neutral beam heated, lower single null plasmas with near zero external torque injection. This regime exhibits good energy confinement (H98y2 ∼ 1) βN 2, high density, access at low input power, no ELMs. New time–resolved measurements of electron ion temperature, plasma rotation, radial electric field as well turbulence, flows, thermal particle transport, linear instability...
Short bursts (1 -2 ms) of gas, injecting ~ 10 17 -10 18 molecules hydrogen as well deuterium, lead to observations phenomena cold pulse propagation in plasmas the ADITYA-U tokamak.After every injection gas-pulse, a sharp increase chord-averaged density followed by an core temperature has been observed.Simultaneously edge and decreases, suggesting due gas-pulse application.It observed that subsequent depend on both value plasma at instant gasinjection amount gas injected up threshold...
Abstract In fusion devices, various techniques are employed for coating the plasma facing components (PFCs) including vessel wall with low-Z material like lithium, boron, and silicon in order to enhance parameters control. ADITYA-Upgrade tokamak, different of lithium conditioning developed implemented obtain uniform sustainable Li on PFCs wall. this paper, two used generate from source reported. one technique, a heated (fixed temperature ∼120 °C) Li-rod is placed inside hydrogen glow...
In the ADITYA Upgrade tokamak, glow discharge wall conditioning (GDC) is performed regularly during high-temperature plasma operation cycle using hydrogen (H) and helium (He) gases. H GDC carried out after long durations (few hours) of operations on every day in automatic mode to control oxygen (O) carbon (C) containing impurities. This leads high retention gas graphite limiter plates stainless steel (SS) vessel walls. Subsequently, outgassing requires a prolonged pumping time recycling...
We present experimental results of the trace argon impurity puffing in ohmic plasmas Aditya-U tokamak performed to study transport behaviour. Argon line emissions visible and Vacuum Ultra Violet (VUV) spectral ranges arising from plasma edge core respectively are measured simultaneously. During experiments, space resolved brightness profile Ar1+ at 472.69 nm (3p44s 2P3/2-3p44p 2D3/2), 473.59 4P5/2-3p44p 4P3/2), 476.49 2P1/2-3p44p 2P3/2), 480.60 4P5/2) recorded using a high resolution...
The effect of a periodic train short gas-puff pulses on the rotation frequency and amplitude drift-tearing modes has been studied in ADITYA/ADITYA-U tokamak.The gas puffs, injecting approximately ~10 17 -10 18 molecules fuel (hydrogen) at one toroidal location, are found to concomitantly decrease mode during period injection then recover back its initial values when pulse is over.This leads modulation that correlated with periodicity injection.The underlying mechanism for this change...
Runaway Electrons (REs) generated during plasma disruptions in fusion grade tokamaks have the potential to severely damage plasma-facing components. Designing optimal discharge scenarios for RE suppression future experiments requires interpretative modeling of current experiments. Multiple been carried out on ADITYA-U tokamak design avoidance and suppression. In this article, we numerically studied two representative pairs discharges. first pair discharges, density was increased by gas puffs...
Abstract We present numerical simulation studies on impurity seeding using nitrogen, neon, and argon gases. These gases are ionized by the electron impact ionization. ions can be at multiply states, recombine again with plasma electrons, radiate energy. The radiation losses estimated a non-coronal equilibrium model. A set of 2D model equations to describe their self-consistent evolution derived interchange turbulence in edge SOL regions solved BOUT++. It is found that (with single or...