A5071569240- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Fusion materials and technologies
- Plasma Diagnostics and Applications
- Laser-Plasma Interactions and Diagnostics
- Particle accelerators and beam dynamics
- Laser-induced spectroscopy and plasma
- Superconducting Materials and Applications
- Atomic and Molecular Physics
- Atomic and Subatomic Physics Research
- Nuclear reactor physics and engineering
- Solar and Space Plasma Dynamics
- Nuclear Physics and Applications
- Photocathodes and Microchannel Plates
- High-pressure geophysics and materials
- Plasma Applications and Diagnostics
- Electrohydrodynamics and Fluid Dynamics
- Laser Design and Applications
- Vacuum and Plasma Arcs
- Microfluidic and Capillary Electrophoresis Applications
- Advanced Sensor and Energy Harvesting Materials
- GNSS positioning and interference
- Power System Optimization and Stability
- Photonic and Optical Devices
- Microfluidic and Bio-sensing Technologies
Institute for Plasma Research
2015-2024
Homi Bhabha National Institute
2024
Pandit Deendayal Petroleum University
2021
BioHybrid Solutions (United States)
2013
National Institute for Fusion Science
2009-2010
National Institute of Technology, Nagano College
2010
The Graduate University for Advanced Studies, SOKENDAI
2007-2009
A flat-field extreme ultraviolet (EUV) spectrometer with a varied line spacing groove grating (1200grooves∕mm at center) has been developed to study the emission spectra from highly ionized medium Z impurities in large helical device (LHD). It covers wavelength range of 50–500Å using mechanically ruled grating, which was later replaced by newly laminar-type holographic for comparative studies. Differences spectral resolution, intensities higher order spectra, and sensitivities were studied...
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...
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...
A flat-field extreme ultraviolet (EUV) spectrometer with a nominal 2400 grooves/mm aberration-corrected ruled grating has been developed to analyze the emission spectrum in wavelength range of 10 130 from large helical device (LHD) plasmas. Spectral properties such as resolution, sensitivity, contribution higher-order light, and background stray light have studied using spectra mainly intrinsic impurities, e.g., C Fe. It is found that well resolves closely existing spectral lines highly...
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 current ~160 kA discharge duration beyond ~250 ms with flattop ~140 obtained the first time ADITYA. The reproducibility has improved considerably lithium wall conditioning, are by precisely controlling position plasma. In these discharges,...
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...
Remarkable progress in the physical parameters of net-current free plasmas has been made Large Helical Device (LHD) since last Fusion Energy Conference Chengdu, 2006 (Motojima et al 2007 Nucl. 47 S668 ). The beta value reached 5% and a high-beta state beyond 4.5% from diamagnetic measurement maintained for longer than 100 times energy confinement time. density temperature regimes have also extended. central exceeded 1 × 10 21 m −3 due to formation an internal diffusion barrier . ion 5.2 keV...
Transport characteristics of the stochastic magnetic boundary Large Helical Device (LHD) are investigated, based on three-dimensional Monte-Carlo Braginskii-type fluid model code, EMC3, coupled with kinetic neutral transport code EIRENE, in direct comparison experimental observations for aspects relation between topology and resulting terms counter acting flux tube flows impurity screening/transport. Divertor probe measurements show a rather weak divertor parameter dependence upstream...
Four resonance transitions of CIII (977.03 Å:2s2 S10-2s2p P11), CIV (1550 Å:2s S2-2p P2), CV (40.27 Å:1s2 S10-1s2p and CVI (33.73 Å:1s P2) have been observed in vacuum ultraviolet extreme regions to study the edge carbon impurity transport Large Helical Device ergodic layer. Here, indicate influx at outside boundary layer ions higher ionization stages, which already experienced The intensity ratio CV+CVI CIII+CIV, therefore, represents degree screening, has analyzed with different plasma...
Spectroscopic data on high-Z materials for impurity diagnostics are important due to its possible use as a plasma facing component in the next generation fusion device. For this purpose molybdenum and tungsten injected by an pellet injector into large helical device (LHD) plasmas. Emissions from such highly ionized elements mostly fall extreme ultraviolet (EUV) soft X-ray ranges. The EUV spectra range of 20-500 Å recorded using flat-field spectrometer. observed emissions identified with help...
In the present work, polyester film and fabric were exposed to dielectric barrier discharge in air at atmospheric pressure increase wettability dye uptake properties. The surface of treated samples was analyzed using contact angle goniometer, scanning electron microscope, Fourier transform infrared spectrometer. plasma characterized electrically optically understand chemistry. Significant improvement substrate substantial decrease water after treatment attributed formation polar functional...
A steady state superconducting tokamak (SST-1) has been commissioned after the successful experimental and engineering validations of its critical sub-systems. During 'engineering validation phase' SST-1; cryostat was demonstrated to be leak-tight in all operational scenarios, 80 K thermal shields were uniformly cooled without regions 'thermal runaway hot spots', toroidal field magnets their nominal conditions charged up 1.5 T at major radius. The further assembled SST-1 machine shell a...
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....
The experimental work reported here is a validation of Langmuir probe measurements against emission spectroscopic and discharge resistivity atmospheric glow plasma parameters. density are close to that obtained by spectroscopy measurement. However, it found the electron temperature measurement higher than technique. Variation parameters with operating voltage frequency, which estimated three techniques, shows similar trend.
Intense visible lines from Be-like oxygen impurity are routinely observed in the Aditya tokamak. The spatial profile of brightness a spectral line (2p3p 3D3–2p3d 3F4) at 650.024 nm is used to investigate transport typical discharges A 1.0 m multi-track spectrometer (Czerny–Turner) capable simultaneous measurements eight sight obtain radial O4+ emission. emissivity emission obtained using an Abel-like matrix inversion. coefficients determined by reproducing experimentally measured profiles...
This paper summarizes the results of recent dedicated experiments on disruption control and runaway mitigation carried out in ADITYA, which are utmost importance for successful operation large size tokamaks, such as ITER. It is quite a well-known fact that disruptions tokamaks must be avoided. Disruptions, induced by hydrogen gas puffing, successfully avoided two innovative techniques ADITYA using bias electrode placed inside last closed flux surface applying an ion cyclotron resonance pulse...
A diagnostic system based on a multi-fiber input high resolution spectrograph has been set up the Aditya tokamak (Bhatt et al 1989 Ind. J. Pure Appl. Phys. 27 710) for utilizing passive light emission to measure different kinds of plasma flow and identify location emissions hydrogen impurities along with their temperatures. Eight simultaneous vertically collimated lines-of-sight from top port view poloidal cross-section plasma. This arrangement simplifies analysis spectra in terms making...
Z eff measurement system using a visible spectrometer has been newly designed and constructed instead of an old interference filter to eliminate line emissions from the signal measure Zeff value in low-density plasmas. The consists Czerny–Turner-type with charge-coupled device camera 44 optical fibers vertical array. is equipped additional toroidal mirror for further reduction astigmatism addition flat two spherical mirrors three gratings (110, 120, 1200grooves∕mm) 30cm focal length. images...
The feasibility of inferring the plasma parameters a Penning discharge in helium, from experimentally observed intensities number spectral lines visible wavelength region, is explored. collisional-radiative model ADAS (atomic data analysis structure) code and database has been used for this analysis. electron density, temperature, ground-state atom ion densities also 2 3S metastable state density are thus estimated. results encouraging. derived then to obtain few vacuum ultraviolet (VUV)...
Lithiumization of the vacuum vessel wall Aditya tokamak using a lithium rod exposed to glow discharge cleaning plasma has been done understand its effect on performance. After Li-coating, an increment ∼100 eV in electron temperature observed most discharges compared without Li coating, and shot reproducibility is considerably improved. Detailed studies impurity behaviour hydrogen recycling are made coated by observing spectral lines hydrogen, carbon, oxygen visible region optical fiber,...
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...
In H 2 discharges of large helical device (LHD), H-mode-like transition has been obtained with edge localized mode (ELM)-like bursts in an outwardly shifted configuration R ax = 4.00 m extremely thick ergodic layer, where the ι/2π 1 position is located middle layer. This can be triggered by changing P NBI (<12 MW) from 3 beams to a density range (4–8) × 10 13 cm −3 . The spontaneous also observed during stable discharge constant heating power and density, steep pressure gradient formed at...