A5018849285- Magnetic confinement fusion research
- Fusion materials and technologies
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Nuclear reactor physics and engineering
- Laser-induced spectroscopy and plasma
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Photocathodes and Microchannel Plates
- Nuclear Physics and Applications
- Calibration and Measurement Techniques
- Radiation Detection and Scintillator Technologies
- Atomic and Subatomic Physics Research
- Digital Holography and Microscopy
- Solar and Space Plasma Dynamics
- Atomic and Molecular Physics
- Spectroscopy and Laser Applications
- Advanced Optical Sensing Technologies
- Solid State Laser Technologies
- Model Reduction and Neural Networks
- Aerodynamics and Acoustics in Jet Flows
- Fluid Dynamics and Turbulent Flows
- Laser Material Processing Techniques
- Atmospheric Ozone and Climate
ITER
2018-2024
Ioffe Institute
2022
Culham Centre for Fusion Energy
2009-2020
Culham Science Centre
2009-2020
Royal Military Academy
2020
University of York
2013
École Polytechnique Fédérale de Lausanne
2005-2012
Queen's University Belfast
2009
United Kingdom Atomic Energy Authority
2008-2009
Imperial College London
2009
This paper reports the impact on confinement and power load of high-shape 2.5 MA ELMy H-mode scenario at JET a change from all carbon plasma-facing components to an metal wall. In preparation this change, systematic studies reduction as result fuelling in combination with nitrogen seeding were carried out JET-C are compared their counterpart metallic An unexpected significant is reported decrease pedestal but partially recovered injection nitrogen.
A Thomson scattering system is being developed for Joint European Torus with 15 mm spatial resolution and a foreseen accuracy temperature better than 15% at density of 1019 m−3. This required the internal transport barrier edge pedestal it can not be fully achieved present light detection ranging systems. The laser this Nd:YAG, 5 Joule, 20 Hz. Scattering volumes from R=2.9 m to R=3.9 are imaged onto 1 diameter fibers, F/25 collection aperture. Two fibers used per volume. Using optical delay...
The instrument function of the high resolution Thomson scattering (HRTS) diagnostic in Joint European Torus (JET) has been calculated for use improved pedestal profile analysis. full width at half maximum (FWHM) spatial response is (22 ± 1) mm original HRTS system configuration and depends on particular magnetic topology JET plasmas. An improvement to optical design laser input presented. smearing across flux surfaces reduced this design. new implemented (from JPN 78742, July 2009)...
In both JET and ASDEX Upgrade (AUG) the plasma energy confinement has been affected by presence of a metal wall requirement increased gas-fuelling to avoid tungsten pollution plasma.In with beryllium/tungsten high triangularity baseline H-mode scenario (i.e.similar ITER reference scenario) strongest benefit shaping give good normalised H 98 ~1 at Greenwald density fraction f GW ~0.8 disappeared.In AUG full could be achieved in plasmas, albeit elevated pressure β N >2.The lost respect carbon...
Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation M. N. A. Beurskens, T. H. Osborne, P. Schneider, E. Wolfrum, L. Frassinetti, R. Groebner, Lomas, I. Nunes, S. Saarelma, Scannell, B. Snyder, D. Zarzoso, Balboa, Bray, Brix, J. Flanagan, C. Giroud, Giovannozzi, Kempenaars, Loarte, de la Luna, G. Maddison, F. Maggi, McDonald, Pasqualotto, Saibene, Sartori, Emilia...
A new technique has been developed to produce plasmas with improved confinement relative the H98,y2 scaling law (ITER Physics Expert Groups on Confinement and Transport Modelling Database ITER Basics Editors EDA 1999 Nucl. Fusion 39 2175) JET tokamak. In mid-size tokamaks ASDEX upgrade DIII-D heating during current formation is used a flat q-profile minimum close 1. On this leads q-profiles similar q but opposite other not an state. By changing method utilizing faster ramp temporary higher...
Type I ELMy H-mode operation in JET with the ITER-like Be/W wall (JET-ILW) generally occurs at lower pedestal pressures compared to those full carbon (JET-C). The density is similar but temperature where type ELMs occur reduced and below so-called critical I–type III transition reported JET-C experiments. Furthermore, confinement factor H98(y,2) baseline plasmas JET-ILW low power fractions Ploss/Pthr,08 < 2 (where Ploss (Pin − dW/dt), Pthr,08 L–H threshold from Martin et al 2008 (J. Phys....
This paper presents the experimental characterization of pedestal parameters, edge localized mode (ELM) energy, and particle losses from main plasma corresponding ELM energy fluxes on facing components for a series dedicated experiments in Joint European Torus (JET). From these experiments, it is demonstrated that simple hypothesis relating peeling-ballooning linear instability to not valid. Contrary previous observations at lower triangularities, small low collisionality have been obtained...
The stationary edge localized mode (ELM)-free 'Quiescent H-mode' (QH-mode) regime, obtained with counter neutral beam injection, is studied in ASDEX Upgrade and Joint European Torus. QH-mode plasmas have high pedestal core ion temperatures together good High-confinement (H-mode). ELMs are replaced by continuous MHD oscillations, the 'edge harmonic oscillation' (EHO) 'high frequency oscillation'. Stationarity of particle impurity densities linked to occurrence these modes. EHO location...
Experiments on JET with a carbon-fibre composite wall have explored the reduction of steady-state power load in an ELMy H-mode scenario at high Greenwald fraction ∼0.8, constant and close to L H transition. This paper reports systematic study due effect fuelling combination seeding over wide range pedestal density ((4–8) × 1019 m−3) detailed documentation divertor, main plasma conditions, as well comparative two extrinsic impurity nitrogen neon. It also impact overall behaviour, possible...
This paper describes experiments with highly shaped JET H-mode plasmas, which were directed to developing regimes where Type I ELMs are replaced by other edge relaxations, while maintaining the pedestal pressure of ELMy H-modes. It was found that II coexisted I, up densities order Greenwald limit, III appear, and good confinement lost. Only at highest collisionality it observed completely replace I. At high βp q95, 'grassy' completely. The MHD spectra characteristics for grassy significantly...
Externally launched lower hybrid (LH) waves do not propagate into the plasma core during operations of JET with radial profiles relatively high density even at periphery, approaching condition necessary for ITER. Modelling results indicate that this problem would be caused by parametric instability (PI)-induced LH spectral broadening, which is expected to occur in edge and prevents coupled power penetrating core. However, operation electron temperature diminish PI effect extend current drive...
We present the pedestal structure, as determined from high-resolution Thomson scattering measurements, for a database of low and high triangularity (δ ≈ 0.22–0.39) 2.5 MA, type I ELMy H-mode JET plasmas after installation new ITER-like wall (JET-ILW). The explores effect increasing deuterium fuelling nitrogen seeding with view to explain observed changes in performance (edge global). JET-ILW show no significant change structure gas dosing. These results are good agreement EPED1 predictions....
Nine type-I ELMy H-mode discharges in diagnostic optimized configuration JET are analysed with the EDGE2D/NIMBUS package. EDGE2D solves fluid equations for conservation of particles, momentum and energy hydrogenic impurity ions, while neutrals followed two-dimensional Monte Carlo module NIMBUS. Using external boundary conditions from experiment, perpendicular heat conductivities χi,e particle transport coefficients D, v varied until good agreement between code result measured data is...
The dependence of the H-mode edge transport barrier width on normalized ion gyroradius (ρ * = ρ/a) in discharges with type I ELMs was examined experiments combining data for JET and DIII-D tokamaks.The plasma configuration as well local pressure (β), collisionality (ν ), Mach number ratio electron temperature at pedestal top were kept constant, while ρ varied by a factor four.The steep gradient region (T e ) density (n pedestals
In the International Thermonuclear Experimental Reactor under construction in southern France, there will be a need for continuous measuring of erosion at wall, after reactor starts operating. A two-wavelength interferometric technique based on digital holography is proposed measurement. This has ability to tackle challenging environmental conditions within by long-distance measurement, where relay optic used imaging investigated surface detector. We show that shape measurements objects...
Abstract A dimensionless collisionality scan in low-triangularity plasmas the Joint European Torus with ITER-like wall (JET-ILW) has been performed. The increase of normalized energy confinement (defined as ratio between thermal and Bohm time) decreasing is observed. Moreover, at low collisionality, a factor H 98 , comparable to JET-C, achieved. At high related degraded pedestal stability reduction density-profile peaking. due both an core regions. improvement stability. driven by (i)...
Advanced scenario plasmas must often be run at low densities and high power, leading to hot edge temperatures consequent power handling issues plasma - surface interaction zones. Experiments ...
The former all-carbon wall on JET has been replaced with beryllium in the main torus and tungsten divertor to mimic surface materials envisaged for ITER. Comparisons are presented between type I H-mode characteristics each design by examining respective scans over deuterium fuelling impurity seeding, required ameliorate exhaust loads both at full capability Attention is focused upon a common high-triangularity, single-null configuration 2.5 MA, q95 ≈ 3.5 yielding most robust all-C...
Three dimensionless scans in the normalized Larmor radius ρ*, collisionality ν* and plasma pressure β have been performed JET with ITER-like wall (JET-ILW).
Experiments are described that have increased our understanding of the transport and stability physics set H-mode edge pedestal width height, determine onset Type-I localized modes (ELMs) produce nonlinear dynamics ELM perturbation in scrape-off layer (SOL). Models now exist for ne profile pe height at ELMs, progress has been made towards models Te evolution. Similarity experiments between DIII-D JET suggested neutral penetration plays an important role relationship pedestal. Plasma appears...
Since it is uncertain if ITER operation compatible with type-I edge localized modes (ELMs), the study of alternative ELM regimes an urgent issue.This paper reports on experiments JET aiming to find scenarios small ELMs and good confinement, such as type-II in ASDEX Upgrade, enhanced D-alpha H-mode Alcator C-mod or grassy JT-60U.The includes shape variations, especially closeness a double-null configuration, variations q 95 , density beta poloidal.H-mode pedestals without have been observed...
This paper summarizes results of dimensionless identity experiments in JT-60U and JET, aimed at the comparison H-mode pedestal ELM behaviour two devices. Given their similar size, matched plasmas are also dimensional parameters (in particular, plasma minor radius a is same JET JT-60U). Power density scans were carried out values Ip, providing q scan (q95 = 3.1 5.1) with fixed (and matched) toroidal field. Contrary to initial expectations, match between devices was quite difficult achieve. In...
Pedestal and scrape-off layer (SOL) dynamics due to edge localized modes (ELMs) have been studied on JET with improved diagnostic capability. The new high resolution Thomson scattering system enables detailed measurement of the space time evolution T e n pedestal profiles. SOL for type I ELMy H-mode plasmas a wide range plasma conditions. During short period <200 µs after ELM event radial profiles filaments in electron density temperature observed. After that is increased remains several...