A5000826365- Magnetic confinement fusion research
- Fusion materials and technologies
- Superconducting Materials and Applications
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Atomic and Molecular Physics
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Nuclear reactor physics and engineering
- Restraint-Related Deaths
- Astro and Planetary Science
- Solar and Space Plasma Dynamics
United Kingdom Atomic Energy Authority
2022-2025
Culham Science Centre
2020-2024
University of York
2019-2023
Culham Centre for Fusion Energy
2021-2023
We present the first analysis of atomic and molecular processes at play during detachment in MAST-U Super-X divertor using spectroscopy data. Our indicates can be separated into four sequential phases: First, ionisation region detaches from target onset leaving a increased densities downstream. The plasma interacts with these molecules, resulting ions ($D_2^+$ and/or $D_2^- \rightarrow D + D^-$) that further react leading to Molecular Activated Recombination Dissociation (MAR MAD), which...
The mega amp spherical tokamak (MAST) was a low aspect ratio device (R/a = 0.85/0.65 ~ 1.3) with similar poloidal cross-section to other medium-size tokamaks. physics programme concentrates on addressing key issues for the operation of ITER, design DEMO and future tokamaks by utilising high resolution diagnostic measurements closely coupled theory modelling significantly advance our understanding. An empirical scaling energy confinement time that favours higher power, lower collisionality...
This paper shows experimental results from the TCV tokamak that indicate plasma-molecule interactions involving $D_2^+$ and possibly $D^-$ play an important role as sinks of energy (through hydrogenic radiation well dissociation) particles during divertor detachment if low target temperatures ($< 3$ eV) are achieved. Both molecular activated recombination (MAR) ion source reduction due to a power limitation effect shown be in reducing flux density ramp. In contrast, electron-ion (EIR) sink...
Abstract Detachment, an important mechanism for reducing target heat deposition, is achieved through reductions in power, particle and momentum; which are induced plasma–atom plasma–molecule interactions. Experimental research how those reactions precisely contribute to detachment limited. Both as well interactions can result excited hydrogen atoms emit atomic line emission. In this work, we investigate a new Balmer Spectroscopy technique Plasma–Molecule Interaction—BaSPMI. This first...
In this work we provide experimental insights into the impact of plasma–molecule interactions on target ion flux decrease during divertor detachment achieved through a core density ramp in TCV tokamak. Our improved analysis hydrogen Balmer series shows that processes are strongly contributing to intensities and substantially alter particle balance. We find Molecular Activated Recombination (MAR) sinks from H2+ (and possibly H−) factor ∼5 larger than Electron–Ion (EIR) significant contributor...
Abstract The SOLPS-ITER code has been utilised to study the movement of detachment front location from target towards X-point for MAST-U Super-X plasmas. Two sets detached steady state solutions are obtained by either varying deuterium ( D 2 ) fuelling rate or nitrogen N seeding scan corresponding ‘control’ parameters outboard midplane density, <?CDATA $n_\mathrm{u}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>n</mml:mi> <mml:mrow> <mml:mi...
Abstract 2D profiles of electron density and neutral temperature are inferred from multi-delay Coherence Imaging Spectroscopy data divertor plasmas using a non-linear inversion technique. The inference is based on imaging the spectral line-broadening Balmer lines can differentiate between Doppler Stark broadening components by measuring fringe contrast at multiple interferometric delays simultaneously. model has been applied to images generated simulated evaluate its performance. Typical...
A technique, volumetric power optimization, is presented for enhancing the output of magnetic confinement fusion devices. Applied to a tokamak, this approach involves shifting burning plasma region larger volume while introducing minimal perturbations boundary shape. This edge perturbation—squareness—is analogous pinching and stretching boundary. Stability calculations confirm that alteration compatible with maintaining stability. optimization method optimizing could improve performance...
Total flux expansion, a divertor magnetic topology design choice embodied in the Super-X divertor, is predicted through simple analytic models and SOLPS calculations to reduce plasma impurity density detachment thresholds as outer separatrix leg position strike-point major radius, Rt, are increased. However, those predictions contradicted by recent TCV experimental results. In this study, utilizing SOLPS-ITER code, we able both match results demonstrate that effect of total expansion...
Abstract MAST-U has recently started operating with a Super-X divertor, designed to increase total flux expansion and neutral trapping, both predicted through simple analytic models SOLPS calculations reduce the plasma impurity density detachment thresholds. In this study, utilising SOLPS-ITER code, we are quantifying possible gain allowed by baffling geometry, in terms of access detachment. We show that significant reduction upstream threshold (up factor 1.6) could be achieved MAST-U, for...
Abstract JET-ILW type I ELMy H-modes at 2.5 MA/2.8 T with constant NBI heating (23 MW) and gas fuelling rate were performed, utilising edge localised mode (ELM) pacing by vertical kicks plasma shaping (triangularity, δ ) as tools to disentangle the effects of ELMs, inter-ELM transport stability on pedestal particle balance. In agreement previous studies, confinement improves increasing , mostly due a significant increase in density while ELM frequency ( <?CDATA $f_{\mathrm{ELM}}$?> <mml:math...
Abstract The role of ion-molecule ( <?CDATA $D^+-D_2$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mi>D</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:mo>−</mml:mo> <mml:msub> <mml:mn>2</mml:mn> </mml:msub> </mml:math> ) elastic collisions in strongly detached divertor conditions has been studied the MAST-U Super-X configuration using SOLPS-ITER. Two steady state solutions were compared, one obtained through a main-ion fuelling scan and other...
Abstract We present results of the design, implementation and testing a Bayesian multi-diagnostic inference system which combines various divertor diagnostics to infer 2D fields electron temperature T e , density n deuterium neutral 0 in divertor. The was tested using synthetic diagnostic measurements derived from SOLPS-ITER fluid code predictions MAST-U Super-X include appropriate added noise. Two simulations different states detachment, taken scan nitrogen seeding rate, were used as...
The high heat fluxes to the divertor during edge localised mode (ELM) instabilities have be reduced for a sustainable future tokamak reactor.A solution reduce could Super-X divertor, which will tested on MAST-U.ELM simulations MAST-U plasmas been obtained, using JOREK.A factor 10 decrease in peak flux outer target and almost 8 ELM energy fluence when comparing conventional configuration has found.A detached case, after roll-over parallel electron density flux, is used as starting point...
Abstract The role of neutral and charged hydrogenic molecules in detached regimes tokamak plasmas is investigated using a simplified 1D numerical model. Using MAST Upgrade like conditions, simulations are implemented to study the rollover target flux <?CDATA $\Gamma $?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="normal">Γ</mml:mi> </mml:math> upstream density scan. It found that if ${{\text{H}}_2}$?> <mml:mrow> <mml:msub>...
2D profiles of electron density and neutral temperature are inferred from multi-delay Coherence Imaging Spectroscopy data divertor plasmas using a non-linear inversion technique. The inference is based on imaging the spectral line-broadening Balmer lines can differentiate between Doppler Stark broadening components by measuring fringe contrast at multiple interferometric delays simultaneously. model has been applied to images generated simulated evaluate its performance. Typical mean...
A new burn control scheme for tokamaks is described where the total fusion power controlled by adjusting plasma volume fraction that packed into dense regions. In an example spherical tokamak burning plasma, modifying edge squareness doubled at almost constant and density. Therefore, increased could be extremely beneficial to a reactor desirable load balancing. Experiments have observed impact of on modified core volume, highlighting practical relevance this approach.
MAST-U has recently started operating with a Super-X divertor, designed to increase total flux expansion and neutral trapping, both predicted through simple analytic models SOLPS calculations reduce the plasma impurity density detachment thresholds. In this study, utilising SOLPS-ITER code, we are quantifying possible gain allowed by baffling geometry, in terms of access detachment. We show that significant reduction upstream threshold (up factor 1.6) could be achieved MAST-U, for Super-X,...
This paper shows experimental results from the TCV tokamak that indicate plasma-molecule interactions involving $D_2^+$ and possibly $D^-$ play an important role as sinks of energy (through hydrogenic radiation well dissociation) particles during divertor detachment if low target temperatures ($< 3$ eV) are achieved. Both molecular activated recombination (MAR) ion source reduction due to a power limitation effect shown be in reducing flux core density ramp. In contrast, electron-ion (EIR)...