A5042735454- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Particle accelerators and beam dynamics
- Fusion materials and technologies
- Superconducting Materials and Applications
- Plasma Diagnostics and Applications
- Solar and Space Plasma Dynamics
- Dust and Plasma Wave Phenomena
- Laser-Plasma Interactions and Diagnostics
- Physics of Superconductivity and Magnetism
- Particle Accelerators and Free-Electron Lasers
- Nuclear reactor physics and engineering
- Cold Atom Physics and Bose-Einstein Condensates
- Pulsed Power Technology Applications
- Nuclear Physics and Applications
- Nuclear Engineering Thermal-Hydraulics
- Atomic and Subatomic Physics Research
- Aerosol Filtration and Electrostatic Precipitation
- Advanced Data Storage Technologies
Institute for Plasma Research
2016-2025
Homi Bhabha National Institute
2019-2025
Extreme Light Infrastructure - Nuclear Physics
2018
Horia Hulubei National Institute for R and D in Physics and Nuclear Engineering
2018
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,...
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...
Formation of a density blob and its motion in the edge scrape-off layer (SOL) tokamak plasma have been simulated using two-dimensional, two-field, fluid model equations. The simulation results show that blobs form or edge-to-SOL transition region where poloidal velocity shear is maximum. From numerical data, condition for formation has obtained. Dynamics detached SOL regions studied. It observed not all are capable ejection deep into SOL. A their also discussed. Radial particle transport...
We report on a model study of the merging two electromagnetically interacting blobs, which have unidirectional currents and are located in tokamak edge region high beta plasma. Unlike conventional plasma blobs with dipolar that originate from resistive drift/interchange turbulence, these filamentary arise edge-localized mode ejection events. Two such can interact strongly to merge each other poloidal direction. Our detailed simulations reveal rotate about during process occurs rate...
A novel two-dimensional (2D) fluid model is proposed for investigating flux-driven plasma turbulence in the tokamak edge and scrape-off layer (SOL). Unlike most previous simulations of this region, 2D treats two regions a consolidated manner with smooth transition region between. The unified simpler less computer intensive than 3D models, but captures features SOL turbulence. It also illustrates influence on transport, something not captured by earlier simulations. Existence an equilibrium...
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...
The formation of a density blob in the boundary region tokamak plasma is widely believed to be due presence poloidal velocity shear that differentially breaks off radially elongated streamer structure. However, blobs have also been experimentally detected absence shear. We ascribe such differential stretching arising from radial and thereby present unified picture breaking mechanism takes into account both processes synergistic manner. Our universal condition for validated detailed numerical...
Abstract Anomalous plasma transport in the boundary region of a tokamak is commonly associated with formation and evolution coherent density structures known as blobs. Recently, theory for universal mechanism blob has been put forward. It based on breaking process radially elongated streamer due to poloidal radial velocity shears. The well supported by two-dimensional three-dimensional numerical simulation results but lacks experimental validation. In this work, we report first ever...
This paper presents a simple analysis of the fraction blobs observed in scrape-off layer NSTX and calculates correlation between this blob various plasma parameters. The measurements were made using gas puff imaging (GPI) diagnostic on database 103 shots from 2010 with neutral beam power PNBI = 0–6 MW. ranged fb 0.1% to 4.8%, where is defined as time GPI signal was larger than three times its average value within 0–7.5 cm outside separatrix. generally decreased increasing injection lower...
Abstract In the presence of magnetic curvature and density/pressure inhomogeneity, edge scrape-off layer (SOL) regions a tokamak plasma are highly turbulent mainly because drift/interchange instability mechanisms. The divergence ion polarization drift contains diamagnetic <?CDATA $\vec{E}\times \vec{B}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mrow> <mml:mi>E</mml:mi> </mml:mrow> <mml:mo>⃗</mml:mo> </mml:mover>...
Two-dimensional (2D) interchange turbulence in the scrape-off layer of tokamak plasmas and their subsequent contribution to anomalous plasma transport has been studied recent years using electron continuity, current balance, energy equations. In this paper, numerically it is demonstrated that inclusion ion equation simulation changes nature turbulence. Finite temperature reduces floating potential by about 15% compared with cold approximation also radial electric field. Rotation blobs at an...
An experiment aimed at investigating the cause of fluctuation suppression by gas puffing in edge and scrape-off layer plasma ADITYA tokamak is reported. The accompanied a flattening radial profiles floating potential, density electrostatic Reynolds stress. Both simultaneous reduction particle flux occur throughout observed region edge. bolometer data also show an increase radiation from 20% to 40% input power during puff. These results indicate significant role cooling mechanism are shown be...
Numerical simulations of the interchange plasma turbulence in presence medium-Z impurities (N2, Ne, and Ar) seeding have been performed using BOUT++. These simulation results are used to study impurity transport mechanism edge scrape-off layer (SOL) regions. An analytical relation for ion density with vorticity, sources sinks, mass charge ratio has also derived. Simulation shows that Ar+ moves more strongly inward compared N+ Ne+ verified from relation. The most abundant species move both...
Turbulence in Scrape-off layer (SOL) of tokamak plasma has been studied numerically using interchange modes with the help electron continuity, quasineutrality, and ion energy equations. Electron temperature is assumed uniform. We have dynamics seeded blob turbulence to identify role its gradient. The elongates poloidally reduces radial velocity. Initial dipole nature potential breaks generates few more dipoles during propagation SOL. Plasma simulation shows elongated density structures that...
The role of neutral gas molecules in the Scrape-off Layer (SOL) region tokamak plasma is important as it expected to modify turbulence. Two-dimensional model has been used that consists electron continuity, molecular ion quasi-neutrality, energy, and continuity equations presence impact ionizations other non-ionizing collisions. growth rate obtained from these presented using linear theory. It observed increases with ionization coefficients. nonlinear are solved numerically absence...
The modification of interchange plasma turbulence in the scrape-off layer (SOL) region by presence hot and cold neutral gas molecules has been studied. nonlinear equations have solved numerically using two different simulations (“uniform-Te” “varying-Te”), results obtained from both models compared. neutrals, responsible for increase electron density SOL, also account more ionization molecules. effect neutrals on is almost similar “uniform-Te” model, but “varying-Te” influence very small,...
The effects of nitrogen gas seeding in the edge and scrape-off layer (SOL) regions a tokamak plasma are studied through 2D fluid simulations using BOUT++ code. Proper account is taken presence multiple charged states ions due to ionization, recombination, dissociation processes, self-consistent study interaction these with turbulent SOL carried out. model includes polarization drifts main impurity for determining vorticity. Nitrogen found modify turbulence as well influence profiles...
Two dimensional interchange turbulence has been used to describe neon gas interaction with tokamak plasma, and is able include anomalous transport effects self-consistently in the edge scrape-off layer (SOL) regions. Model equations related plasma coupled have solved numerically using BOUT++ framework code. different fluid models of investigated, this context a few results Aditya are presented. Numerical indicate that ionization radiative cooling processes modify turbulence. The existence...
Abstract Nonlinear coherent dense plasma structures—‘blobs’—that form in the turbulent edge of a tokamak play an important role anomalous nature transport that region. A blob is normally formed when another kind structure—a radially elongated streamer structure—breaks due to differential stretching radial and poloidal directions. We investigate such formation scrape-off layer region by taking into account electron temperature effects. It found shear related gradient electric field plays...
Abstract The ADITYA upgrade (ADITYA-U), a medium-sized <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo>(</mml:mo> <mml:msub> <mml:mi>R</mml:mi> <mml:mn>0</mml:mn> </mml:msub> </mml:mrow> <mml:mo>=</mml:mo> <mml:mn>75</mml:mn> <mml:mtext> cm</mml:mtext> <mml:mo>,</mml:mo> <mml:mstyle scriptlevel="0"/> <mml:mi>a</mml:mi> <mml:mn>25</mml:mn> <mml:mo>)</mml:mo> </mml:math> conventional tokamak facility in India, has been consistently producing...
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...
Conceptual design of a fully solid state power supply system for 1000s ON/ 5000s OFF long pulse operation neutral beam injector is presented. A switched with crowbar used regulated HV power. 400 Hz, 24 phase filament in an integrated closed loop control the buck type arc supplies. Temperature each controllable independent other. An air core transformer secondary RC load passive snubber grid circuit. supervises interlock, protection and safety system.
Major disruptions in Aditya tokamak are initiated by the growth and subsequent locking of m/n = 2/1 3/1 tearing modes, which leads to thermal quench plasma. Thick filaments seen evolve at low field side (LFS) plasma column following quench, during current quench. The number inter filament spacing observed be related with stored energy just prior disruption. Rapid enhancement outward particle flux is phase conductivity reduces considerably. Interchange poloidal wavenumber, inferred grow due...
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...