A5028711446- Magnetic confinement fusion research
- Fusion materials and technologies
- Superconducting Materials and Applications
- Plasma Diagnostics and Applications
- Particle accelerators and beam dynamics
- Laser-Plasma Interactions and Diagnostics
- Nuclear Physics and Applications
- Ionosphere and magnetosphere dynamics
- Nuclear reactor physics and engineering
- Atomic and Molecular Physics
- Laser-induced spectroscopy and plasma
- Metal and Thin Film Mechanics
- Atomic and Subatomic Physics Research
- Diamond and Carbon-based Materials Research
- Vacuum and Plasma Arcs
- Ion-surface interactions and analysis
- Electromagnetic Compatibility and Measurements
- Nuclear Materials and Properties
- Quantum, superfluid, helium dynamics
- Scientific Measurement and Uncertainty Evaluation
- Semiconductor materials and devices
- Laser Design and Applications
- Mass Spectrometry Techniques and Applications
- High-Energy Particle Collisions Research
- Particle Accelerators and Free-Electron Lasers
Oak Ridge National Laboratory
2015-2024
Culham Science Centre
2021-2024
Culham Centre for Fusion Energy
2024
Max Planck Institute for Plasma Physics
2021
Royal Military Academy
2020
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
1995-2015
CEA Cadarache
2013-2015
Oak Ridge Associated Universities
1996-2012
Oak Ridge Institute for Science and Education
2012
École nationale des ponts et chaussées
2012
Particle transport in an ohmically heated tokamak plasma was investigated the Texas Experimental Tokamak (TEXT). Spectroscopic measurements of electron source were used with density to derive particle confinement times from continuity equation. Scalings developed for time density, current, toroidal field, and positioning. Simultaneous measurement electrostatic fluctuations Langmuir probes may suggest a correlation between edge TEXT turbulence. In addition, two major features isolated. First,...
Abstract Using a recently installed impurity powder dropper (IPD), boron (<150 μ m) was injected into lower single null (LSN) L-mode discharges in WEST. IPDs possibly enable real-time wall conditioning of the plasma-facing components and may help to facilitate H-mode access full-tungsten environment The this experiment featured I p = 0.5 MA, B T 3.7 T, q 95 4.3, t pulse 12–30 s, n e,0 ∼ 4 × 10 19 m −2 , P LHCD 4.5 MW. Estimates deuterium particle fluxes, derived from combination visible...
The filterscope is a diagnostic for monitoring visible light emission from plasmas. Light plasma conducted to the via optical fibers. This split into multiple paths, and bandpass filters in each path pass wavelengths, including Dα, Dβ various impurities. filtered then detected by compact photomultipliers resulting data digitized stored. Because of large number channels employed, electronics are designed be compact. Measured intensities absolutely calibrated. Filterscopes presently employed...
The first encouraging experiments demonstrating direct, explicit control of the ${\mathrm{He}}^{2+}$ density in a tokamak plasma have been performed TEXTOR with Advanced Limiter Test-II pump limiter. Helium is injected short gas puff from outside plasma, observed to reach core, and then readily removed plasma. An exhaust efficiency \ensuremath{\sim}8% obtained. Active charge-exchange spectroscopy used study transport within evolution modeled diffusive-convective code.
Recent achievements in studies of the effects ICRF (Ion Cyclotron Range Frequencies) power on SOL (Scrape-Off Layer) and PWI (Plasma Wall Interactions) ASDEX Upgrade (AUG), Alcator C-Mod, JET-ILW are reviewed. Capabilities to diagnose model effect DC biasing associated impurity production at active antennas magnetic field connections described. The experiments show that near-fields can lead not only E × B convection, but also modifications density, which for C-Mod limited a narrow region...
Abstract As part of ITPA-Integrated Operational Scenario activities, this contribution reviews recent experimental characterizations radio-frequency (RF)-induced scrape-off layer (SOL) modifications various tokamaks worldwide and the LArge Plasma Device at UCLA. The phenomenology, as observed using a large variety measurement techniques, is consistent with expectations from RF sheath rectification. Emphasis then put on complex three-dimensional (3D) spatial patterns RF–SOL interaction, in...
Radiative losses along a fixed view into the divertor chamber of DIII-D tokamak [Plasma Physics Controlled Nuclear Fusion Research 1986 (International Atomic Energy Agency, Vienna, 1987), Vol I, p. 159] have been characterized for attached and partially detached discharges by analyzing line-integrated vacuum ultraviolet (VUV) signals. Essentially all emission can be ascribed to carbon deuterium. Because majority most intense lines, which lie at wavelengths above 1100 Å, are not accessible...
Recent measurements of the two-dimensional (2-D) spatial profiles divertor plasma density, temperature, and emissivity in DIII-D tokamak [J. Luxon et al., Proceedings 11th International Conference on Plasma Physics Controlled Nuclear Fusion (International Atomic Energy Agency, Vienna, 1987), p. 159] under highly radiating conditions are presented. Data obtained using a Thomson scattering system other diagnostics optimized for measuring high electron densities low temperatures these detached...
Three identical new WEST Ion Cyclotron Resonance Heating (ICRH) antennas have been designed, assembled then commissioned on plasma from 2013 to 2019.The ICRH system is both load-resilient and compatible with long-pulse operations.The three successfully operated together in 2019 2020.The load resilience capability has demonstrated the antenna feedback controls for phase matching developed.The breakdown detection systems validated protected antennas.The use of combination Lower Hybrid...
In principle, boron (B) as a material has many excellent surface properties, including corrosion resistance, very high hardness, refractory and strong tendency to bond with most substrates. The potential technological benefits of the have not been realized, because it is difficult deposit coatings. B evaporate, does sputter well, cannot be thermally sprayed. this article, first successful deposition results from robust system, based on vacuum (cathodic) arc technology, are reported. Adherent...
Reduction of the net wall particle inventory has been achieved in DIII-D tokamak by use a divertor cryopump for exhaust. A sequence 12 discharges was conducted without helium glow discharge cleaning (HeGDC) and active exhaust, resulting loading 1250 torr.L (8.8*1022 atoms) end sequence. The activated subsequent set 10 discharges. At this discharges, reduced to its initial value or less, i.e. state reference with HeGDC. Plasma performance did not suffer HeGDC that stored energy during ELMy...
The present work concerns the measurements obtained with Tungsten (W) Environment in Steady-state Tokamak (WEST) visible spectroscopy system during first experimental campaign. This has been developed framework of WEST project that equipped existing Tore Supra device a tungsten divertor order to test actively cooled Plasma Facing Components (PFC) view preparing for ITER operation. goal this diagnostic is measure PFC sources and deuterium recycling spectral, spatial, temporal resolution...
Neutral gas analysis, the measurement and evaluation of total partial pressures, is a key technique to study impact neutral dynamics on retention, recycling release processes fuel or impurity species in fusion devices. At JET, experiment closest ITER terms operating parameters size, various detectors techniques for pressure measurements are deployed together characterise during after plasma operation toroidal poloidal locations. An extensive modification JET's sub-divertor diagnostic system...
Abstract Understanding impurity transport in tokamak plasmas is crucial to control radiative losses and material migration future magnetic fusion reactors. In this work we deploy the SolEdge2D-EIRENE code model boundary plasma a WEST discharge, satisfactorily reproducing measurements of both upstream divertor conditions. The spatial distribution oxygen, studied here as representative light impurity, compared vacuum ultraviolet spectroscopy acquired with an oscillating line sight. simulation...
DIII-D currently operates with a single- or double-null open divertor and graphite walls. Active particle control cryopump has demonstrated density control, efficient helium exhaust, reduction of the inventory particles in wall. Gas puffing D2 impurities peak heat flux by factors 3-5 radiation. A combination active cryopumping feedback-controlled gas produced similar control. Experiments neon have shown that radiation is equally-divided between localized zone near X-point mantle around...
The major aspects linked to the use of JET auxiliary heating systems: NBI, ICRF and LHCD, in new ITER-like wall (JET-ILW) are presented. We show that although there were issues related operation each system, efficient safe plasma was obtained with room for higher power. For NBI up 25.7MW safely injected; had be tackled mainly beam shine-through re-ionisation before its entrance into plasma. 5MW coupled L-mode 4MW H-mode; main areas concern RF-sheaths heat loads impurities production. LH, 2.5...
Radio-frequency (RF)-enhanced surface erosion of beryllium (Be) plasma-facing components is explored, for the first time, using ERO code. The code applied to measured, RF-enhanced edge Be line emission at JET outboard limiters, in presence high-power, ion cyclotron-resonance heating (ICRH) L-mode discharges. In this modelling study, RF sheath effect from an ICRH antenna on a magnetically connected, limiter region simulated by adding constant potential local sheath, attempt match measured...
Abstract Experimental data, together with interpretive modeling tools, are examined to study trends in the tungsten (W) source all-W environment of WEST tokamak, both from divertor and main chamber. In particular, a poloidal limiter protecting an ion cyclotron resonance heating (ICRH) antenna is used as proxy for chamber sourcing. The key carried out by stepping up lower hybrid current drive (LHCD) power, only auxiliary power source. Limiter W sources exhibit qualitatively similar...
Abstract High power experiments, up to 9.2 MW with LHCD and ICRH, have been carried out in the full tungsten tokamak WEST. Quasi non inductive discharges achieved allowing extend plasma duration 53 s stationary conditions particular respect contamination. Transitions H mode are observed, H-modes lasting 4 obtained. The increase stored energy is weak since crossing separatrix close L–H threshold. Hot L plasmas (central temperature exceeding 3 keV) a confinement time following ITER L96 scaling...
The first experiments demonstrating exhaust of thermal helium in a diverted, $H$-mode deuterium plasma have been performed on the DIII-D tokamak. helium, introduced via gas puffing, is observed to reach core, and then readily removed form with time constant $\ensuremath{\sim}$10--20 energy-confinzement times by an in-vessel cryopump conditioned argon frosting. Detailed analysis profile evolution suggests that rate limited efficiency pump ( $\ensuremath{\sim}$5%) not intrinsic...