A5065416853- Magnetic confinement fusion research
- Fusion materials and technologies
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Plasma Diagnostics and Applications
- Nuclear reactor physics and engineering
- Solar and Space Plasma Dynamics
- Laser-induced spectroscopy and plasma
- Particle accelerators and beam dynamics
- Atomic and Molecular Physics
- Characterization and Applications of Magnetic Nanoparticles
- Wireless Power Transfer Systems
- ZnO doping and properties
- Advancements in Semiconductor Devices and Circuit Design
- Combustion and Detonation Processes
- Nuclear Engineering Thermal-Hydraulics
- Vacuum and Plasma Arcs
- Seismic Waves and Analysis
- Gas Dynamics and Kinetic Theory
- Refrigeration and Air Conditioning Technologies
- Traffic control and management
- Magneto-Optical Properties and Applications
- Cold Fusion and Nuclear Reactions
- Lattice Boltzmann Simulation Studies
University of York
2018-2025
Culham Science Centre
2014-2024
United Kingdom Atomic Energy Authority
2022-2024
Culham Centre for Fusion Energy
2019-2023
Max Planck Institute for Plasma Physics
2015-2019
Max Planck Society
2016-2019
CEA Cadarache
2013-2017
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2013-2017
Princeton University
2016-2017
ITER
2015
JOREK is a massively parallel fully implicit non-linear extended MHD code for realistic tokamak X-point plasmas. It has become widely used versatile studying large-scale plasma instabilities and their control developed in an international community. This article gives comprehensive overview of the physics models implemented, numerical methods applied solving equations studies performed with code. A dedicated section highlights some verification work done hierarchy different available...
The interaction of static Resonant Magnetic Perturbations (RMPs) with the plasma flows is modeled in toroidal geometry, using non-linear resistive MHD code JOREK, which includes X-point and scrape-off-layer. Two-fluid diamagnetic effects, neoclassical poloidal friction a source rotation are introduced model to describe realistic flows. RMP penetration studied taking self-consistently into account effects these radial electric field evolution. JET-like, MAST, ITER parameters used modeling....
Abstract The tokamak à configuration variable (TCV) continues to leverage its unique shaping capabilities, flexible heating systems and modern control system address critical issues in preparation for ITER a fusion power plant. For the 2019–20 campaign configurational flexibility has been enhanced with installation of removable divertor gas baffles, diagnostic capabilities an extensive set upgrades new dual frequency gyrotrons. baffles reduce coupling between main chamber allow detailed...
Disruptions are a major operational concern for next generation tokamaks, including ITER.They may generate excessive heat loads on plasma facing components, large electromagnetic forces in the machine structures and several MA of multi-MeV runaway electrons.A more complete understanding processes methods to suppress them is necessary ensure safe reliable operation future tokamaks.Runaway electrons were studied at JET-ILW showing that their dependencies (accelerating electric field, avalanche...
A possible mechanism of edge localized modes (ELMs) mitigation by resonant magnetic perturbations (RMPs) is proposed based on the results nonlinear resistive magnetohydrodynamic modeling using jorek code, realistic JET-like plasma parameters and an RMP spectrum JET error-field correction coils (EFCC) with a main toroidal number n=2 were used in simulations. Without RMPs, large ELM relaxation obtained mainly due to most unstable medium-n ballooning mode. The externally imposed drives...
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...
3D non-linear MHD simulations of a D2 massive gas injection (MGI) triggered disruption in JET with the JOREK code provide results which are qualitatively consistent experimental observations and shed light on physics at play. In particular, it is observed that destabilizes large m/n = 2/1 tearing mode, island O-point coinciding deposition region, by enhancing plasma resistivity via cooling. When gets so its inner side reaches q 3/2 surface, mode grows. Simulations suggest this due to...
Abstract The research program of the TCV tokamak ranges from conventional to advanced-tokamak scenarios and alternative divertor configurations, exploratory plasmas driven by theoretical insight, exploiting device’s unique shaping capabilities. Disruption avoidance real-time locked mode prevention or unlocking with electron-cyclotron resonance heating (ECRH) was thoroughly documented, using magnetic radiation triggers. Runaway generation high- Z noble-gas injection runaway dissipation...
The effect of the upcoming TCV divertor upgrade on distribution neutrals and onset detachment is studied using 2D transport code simulations. centered around installation a gas baffle to form chamber variable closure. SOLPS-ITER simulations predict that geometry selected be installed in 2019 increases neutral density by factor ∼5 compression one order magnitude typical single null, Ohmic heated scenarios (330 kW). further with addition auxiliary heating systems (1.2 MW). Simulations show...
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 An integrated data analysis system based on Bayesian inference has been developed for application to from multiple diagnostics over the two-dimensional cross-section of tokamak divertors. The divertor multi-instrument (D-MIBAS) tested a synthetic dataset (including realistic experimental uncertainties) generated SOLPS-ITER predictions MAST-U divertor. resulting was within 6%, 5%, and 30% median absolute percentage error SOLPS-ITER-predicted electron temperature, density, neutral...
JOREK 3D non-linear MHD simulations of a D2 Massive Gas Injection (MGI) triggered disruption in JET are presented and compared detail to experimental data. The MGI creates an overdensity that rapidly expands the direction parallel magnetic field. It also causes growth islands (m/n=2/1 3/2 mainly) seeds 1/1 internal kink mode. O-points all island chains (including 1/1) located front MGI, consistently with observations. A burst activity peak plasma current take place at same time as...
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...
Abstract A reduction of the pedestal pressure with increasing separatrix density over ( n e sep / ped ) has been observed in JET. The physics behind this correlation is investigated. due to two distinct mechanisms. increase till ≈0.4 shifts radially outwards, decreasing peeling-balloning stability and reducing height. effect position saturates above ≈ 0.4. For higher values, ascribed increased turbulent transport and, likely, resistive MHD effects. reduces ∇ /n , η transport. This gradient...
Plasma-molecular interactions generate molecular ions which react with the plasma and contribute to detachment through activated recombination (MAR), reducing ion target flux, dissociation (MAD), both of create excited atoms. Hydrogenic emission from these atoms have been detected experimentally in detached TCV, JET MAST-U deuterium plasmas. The TCV findings, however, were disagreement SOLPS-ITER simulations for indicating a density ($D_2^+$) that was insufficient lead significant hydrogenic...
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 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...
The full dynamics of a multi-edge-localized-mode (ELM) cycle is modeled for the first time in realistic tokamak $X$-point geometry with nonlinear reduced MHD code jorek. diamagnetic rotation found to be instrumental stabilize plasma after an ELM crash and model cyclic reconstruction collapse pressure profile. relaxations are cyclically initiated each pedestal gradient crosses triggering threshold. Diamagnetic drifts also yield near-symmetric power deposition on inner outer divertor target...
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...
The dynamics of a multi-edge localized mode (ELM) cycle as well the ELM mitigation by resonant magnetic perturbations (RMPs) are modeled in realistic tokamak X-point geometry with non-linear reduced MHD code JOREK. diamagnetic rotation is found to be key parameter enabling us reproduce cyclical plasma relaxations and model near-symmetric power deposition on inner outer divertor target plates consistently experimental measurements. Moreover, coupling RMPs unstable modes modify edge topology...
Edge Localized Modes (ELMs) rotating precursors were reported few milliseconds before an ELM crash in several tokamak experiments. Also, the reversal of filaments rotation at is commonly observed. In this article, we present a mathematical model that reproduces as well crash. Linear ballooning theory used to establish formula estimating velocity precursors. The linear study together with nonlinear magnetohydrodynamic simulations give explanation rotations observed experimentally. Unstable...
The process of divertor detachment, whereby heat and particle fluxes to surfaces are strongly diminished, is required reduce loading erosion in a magnetic fusion reactor acceptable levels. In this paper the physics leading decrease total ion current (It), or 'roll-over', experimentally explored on TCV tokamak through characterization location, magnitude role various sinks sources including complete analysis power balance. These first measurements profiles ionisation hydrogenic radiation...