A5056542572- Magnetic confinement fusion research
- Fusion materials and technologies
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Particle accelerators and beam dynamics
- Ionosphere and magnetosphere dynamics
- Nuclear reactor physics and engineering
- Atomic and Molecular Physics
- Plasma Diagnostics and Applications
- Laser-induced spectroscopy and plasma
- Solar and Space Plasma Dynamics
- X-ray Spectroscopy and Fluorescence Analysis
- High-Energy Particle Collisions Research
- Nuclear Physics and Applications
- Nuclear Materials and Properties
- Diamond and Carbon-based Materials Research
- High-pressure geophysics and materials
- Particle Accelerators and Free-Electron Lasers
- Plasma and Flow Control in Aerodynamics
- Hydrogen Storage and Materials
- Radiation Therapy and Dosimetry
- Advanced X-ray Imaging Techniques
- Anomaly Detection Techniques and Applications
- Atomic and Subatomic Physics Research
- Electronic and Structural Properties of Oxides
Queen's University Belfast
2013-2024
Culham Science Centre
2004-2024
United Kingdom Atomic Energy Authority
2020-2024
Culham Centre for Fusion Energy
2001-2024
VTT Technical Research Centre of Finland
2024
Instituto Politécnico de Lisboa
2021
University of Lisbon
2021
Max Planck Institute for Plasma Physics
2014
Max Planck Society
2014
Oak Ridge National Laboratory
2012
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.
The original goals of the JET ITER-like wall included study impact an all W divertor on plasma operation (Coenen et al 2013 Nucl. Fusion 53 073043) and fuel retention (Brezinsek 083023). ITER has recently decided to install a full-tungsten (W) from start operations. One key inputs required in support this decision was possibility melting melt splashing during transients. Damage type can lead modifications surface topology which could higher disruption frequency or compromise subsequent...
Abstract The JET hybrid scenario has been developed from low plasma current carbon wall discharges to the record-breaking Deuterium-Tritium plasmas obtained in 2021 with ITER-like Be/W wall. development started pure Deuterium refinement of current, and toroidal magnetic field choices succeeded solving heat load challenges arising 37 MW injected power ITER like environment, keeping radiation edge core controlled, avoiding MHD instabilities reaching high neutron rates. have re-run Tritium...
This paper reports the progress made at JET-ILW on integrating requirements of reference ITER baseline scenario with normalized confinement factor 1, a pressure 1.8 together partially detached divertor whilst maintaining these conditions over many energy times. The 2.5 MA high triangularity ELMy H-modes are studied two different configurations D-gas injection and nitrogen seeding. power load reduction N seeding is reported. relationship between an increase in pedestal investigated....
Abstract The paper reports the first demonstration of in situ laser-induced desorption — quadrupole mass spectrometry (LID-QMS) application on a large scale fusion device performed summer 2023. LID-QMS allows direct measurements fuel inventory plasma facing components without retrieving them from device. diagnostic desorbs retained gases by heating 3 mm diameter spot wall using 1 ms long laser pulse and detects QMS. Thus, it can measure gas content at any position accessible to laser....
The observation of internal transport barriers (ITBs) in which ion thermal diffusivity is reduced to a neoclassical level has been made for the first time tokamak plasmas fueled with deuterium and tritium ions using broad current density profile. heating profiles required obtain an ITB are similar D-T D-D plasmas. Central temperatures 40 keV plasma pressure gradients ${10}^{6}\mathrm{Pa}/\mathrm{m}$ were observed plasma, leading fusion triple product...
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...
Abstract The recent deuterium–tritium campaign in JET-ILW (DTE2) has provided a unique opportunity to study the isotope dependence of L-H power threshold an ITER-like wall environment (Be and W divertor). Here we present results from dedicated transition experiments at JET-ILW, documenting tritium plasmas, comparing them with matching deuterium hydrogen datasets. From earlier it is known that as plasma isotopic composition changes deuterium, through varying deuterium/hydrogen concentrations,...
Abstract This paper reports the first experiment carried out in deuterium–tritium addressing integration of a radiative divertor for heat-load control with good confinement. Neon seeding was time D–T plasma as part second campaign JET its Be/W wall environment. The technical difficulties linked to re-ionisation heat load are reported T and D–T. compares impact neon on plasmas their D counterpart detachment, localisation radiation, scrape-off profiles, pedestal structure, edge localised modes global
Abstract JET returned to deuterium-tritium operations in 2023 (DTE3 campaign), approximately two years after DTE2. DTE3 was designed as an extension of JET's 2022-2023 deuterium campaigns, which focused on developing scenarios for ITER and DEMO, integrating in-depth physics understanding control schemes. These were evaluated with mixed D-T fuel, using the only remaining tritium-capable tokamak until its closure 2023. A core-edge-SOL integrated H-mode scenario developed tested D-T, showing...
In DT plasmas, toroidal Alfvén eigenmodes (TAEs) can be made unstable by the alpha particles resulting from fusion reactions, and may induce a significant redistribution of fast ions. Recent experiments have been conducted in JET deuterium plasmas order to prepare scenarios aimed at observing alpha-driven TAEs future campaign. Discharges low density, large core temperatures associated with presence internal transport barriers characterised good energetic ion confinement performed. ICRH has...
Abstract Runaway electrons (REs) created during tokamak disruptions pose a threat to the reliable operation of future larger machines. Experiments using shattered pellet injection (SPI) have been carried out at JET investigate ways prevent their generation or suppress them if avoidance is not sufficient. Avoidance possible SPI contains sufficiently low fraction high-Z material, it fired early in advance disruption prone runaway generation. These results are consistent with previous similar...
The disagreement between the weak dependence of energy confinement time on normalized pressure, β, observed in dedicated scans and strongly negative scaling laws used for design next step tokamaks future reactors, remains an outstanding problem. As such, β have been undertaken single null, low triangularity (δ ≈ 0.2) ELMy H-mode plasmas JET with MarkIIGB-SRP divertor. varied by a factor 2.8 (normalized from 0.72 to 2.04) covered range magnetic fields (1.5–2.3 T), plasma currents (1.5–2.75...
This paper covers aspects of long-term evolution intrinsic impurities in the JET tokamak with respect to newly installed ITER-like wall (ILW). At first changes related change over from JET-C JET-ILW beryllium (Be) as main material and tungsten (W) divertor are discussed. The impurity fluxes W studying migration is described. In addition, a statistical analysis transient events causing significant plasma contamination radiation losses shown. findings comprise drop carbon content (×20) (see...
Recent studies dedicated to the characterisation of in-vessel dust in JET with new ITER-like wall (ILW) show that levels are orders magnitude lower compared latter stages carbon-wall (CW) period and decreasing operational time. Less than 1 g was recovered a recent inspection, more 200 material at end JET-CW life. inspection ILW shows low rates re-deposition only small areas damage type likely create particulate matter. Quantifiers from laser scattering techniques also indicate an order...
Perturbative transport experiments have been performed in JET low or reverse magnetic shear plasmas either conditions of fully developed internal barrier (ITB) during a phase where an ITB was not observed. Transient peripheral cooling induced by laser ablation shallow pellet injection, and the ensuing travelling cold pulse used to probe plasma electron and, for first time, also ion channel. Cold pulses through ITBs are observed erode outer part, but, if inner portion survives, it strongly...
Results from recent experiments to study the effects of divertor geometry and increased plasma shaping on L–H transition threshold JET are reported. Equivalent septum configurations run with new replacement plate (SRP) in MkII Gas Box have shown that presence lowers power threshold, Pth, by 20%. For X-point virtual top distances less than 6 cm, SRP plasmas also demonstrate a significant decrease Pth pedestal electron temperature, Te reduced height. Although, plasma's remains above septum,...
ELMy H-modes in helium-4 plasmas provide valuable information on H-mode physics as well a possible early low activation operational phase for next-step tokamaks, such ITER. With this mind, series of experiments were performed JET with pure NBI auxiliary heating (up to 12 MW). A set produced, both the Type I ELM regime and second regime, which showed characteristics similar deuterium III but reverse frequency dependence power. Sawteeth also observed, had behaviour those seen deuterium....
The prediction of impurity peaking in future fusion devices such as ITER necessitates the study dependence on Z transport present devices. In this paper we describe a novel technique to determine impurities with different atomic numbers independently. A has been developed that allows simultaneously measurement Ne and Ar same discharge while minimizing systematic errors spectroscopic measurements. reproduction charge-exchange measured densities, absolute vaccum ultra-violet line intensities...
The provision of measurements metallic impurity densities, Zeff and dilution for a large number discharges within campaign facilitates the analysis trends. Such trends are increasing importance as additional heating power pulse length increase. This is particularly important RF therefore it in particular relevant to assessment ITER-like ICRF antenna (ILA) on JET. To this end, method presented determining metal density, ΔZeff steady-state JET plasmas using passive VUV emission. based...
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...
Beam-target reactions are responsible for a substantial fraction of the fusion power generated in D-T plasmas JET-ILW (Be/W-wall), with ion temperatures 10-12keV and large neutral-beam injection (NBI) power.It is known that injecting D beam ions energies ~100-150keV T-rich has larger potential beam-target than 50:50 D:T plasmas, but such scenario was never developed past experiments performed JET-C (Carbon-wall) TFTR 90's.On top intrinsic advantages using beams neutron production,...
Steady state high performance with improved core confinement and sustainable plasma edge conditions has been approached on JET in a double barrier (DB) mode. The DB mode combines an internal transport of the optimized shear regime ELMy H regime. Improved factor HITER-89 ≈ 2 maintained for four energy times. Ion electron temperature profiles remain peaked mode, while density profile is broad similar shape to conventional profile. improves across whole cross-section, ion heat conductivity...