A5061887892- Plasma Diagnostics and Applications
- Electrohydrodynamics and Fluid Dynamics
- Magnetic confinement fusion research
- Laser-induced spectroscopy and plasma
- Dust and Plasma Wave Phenomena
- Ionosphere and magnetosphere dynamics
- Plasma Applications and Diagnostics
- Vacuum and Plasma Arcs
- Solar and Space Plasma Dynamics
- Diamond and Carbon-based Materials Research
- Fluid Dynamics and Mixing
- Coagulation and Flocculation Studies
- Graphene research and applications
- Fluid Dynamics and Heat Transfer
- Innovative concrete reinforcement materials
- Ion-surface interactions and analysis
- Mass Spectrometry Techniques and Applications
- Gas Dynamics and Kinetic Theory
- Icing and De-icing Technologies
- Fusion materials and technologies
- Structural Behavior of Reinforced Concrete
- Concrete and Cement Materials Research
- Superconducting Materials and Applications
Imperial College London
2016-2019
University of Cambridge
2014-2015
Culham Centre for Fusion Energy
2014
Culham Science Centre
2014
Abstract The Mega Ampère Spherical Tokamak (MAST) programme is strongly focused on addressing key physics issues in preparation for operation of ITER as well providing solutions DEMO design choices. In this regard, MAST has provided results understanding and optimizing H-mode confinement, operating with smaller edge localized modes (ELMs), predicting handling plasma exhaust tailoring auxiliary current drive. all cases, the high-resolution diagnostic capability complemented by sophisticated...
The ever-decreasing size of nanoscale emitters necessitates a shift away from using planar theories electron emission to analyze experimental results. Returning the problem's roots, authors develop comprehensive theory field and thermal grounded spheres as small 2 nm in radius. Precise expressions for emitted current show that overestimates it by several orders magnitude. These results are applicable dusty plasmas many industrial processes involving aerosols powders, well those producing...
Many plasma applications involve the coming into contact with a liquid surface. Previous analyses of stability such surfaces have neglected presence sheath region between bulk and liquid. Large electric fields, typically in excess several MV m−1, strong ion flows are present this region. This paper considers linear perturbation analysis liquid-sheath interface order to find marginal condition for instability. shows that molten metal tokamak edge plasmas stable against field, if normal is...
The three-dimensional plasma boundary displacement induced by long-lasting core magnetohydrodynamic (MHD) instabilities has been measured in JET, MAST and NSTX.Only saturated are considered here since transient rapidly growing modes which degrade confinement act as potential triggers for disruptions bring more fundamental concerns than displacements.The displacements usually small, although extreme cases when the rotation braking is strong, a significant global can be observed.The...
The behavior of rotating and/or charged drops is a classic problem in fluid mechanics with multitude industrial applications. Theoretical studies such liquid have also provided important insights into fundamental physical processes across nuclear and astrophysical lengthscales. However, the full nonlinear dynamics these are only just beginning to be uncovered by experiments. These effects manifest high sensitivity breakup mechanisms small perturbations initial drop shape observations...
When resonant magnetic perturbations are applied in MAST, the plasma edge boundary experiences a three-dimensional (3D) distortion, which can be few percent of minor radius amplitude, good agreement with ideal 3D equilibrium modelling. This displacement occurs plasmas both radial position feedback control applied, and without feedback. is employed, an non-axisymmetric field lead to exacerbated due ancillary axisymmetric correction, direction correction dependent upon phase respect toroidal...
Fast-camera observations of distinctive forked patterns caused by disintegrating molten metal particles in the JET tokamak are presented. These characterised repeated splitting into pairs equally sized sub-particles; such regularity can only be explained two-lobed bifurcations liquid droplets rotating with velocities excess . speeds consistent longstanding theories particle spin-up magnetized plasmas but at least two orders magnitude greater than any previous measurement plasmas. The...
The present paper deals with a particular case involving magnetic field, namely that of positive column situated in an axial and it is shown the Bohm criterion still holds for normal component ion velocity at plasma boundary. This result considerable interest because Boltzmann relation electron density has not been assumed. It can be recalled was originally derived by using density. In Boltzm ann gradient conditionhas found boundary which leads to usual velocity. Some insight gained...
Abstract The discovery of a highly-charged sheath region at the boundary between plasma and surface is one earliest most important discoveries in science. However physics has almost always been omitted from studies dynamics plasma-facing liquid surfaces which are rapidly assuming pivotal role numerous industrial fusion applications. This paper presents full simulations plasma-sheath-liquid interface finds good agreement with theoretical stability limits experimental observations cone...
The interaction of a small object with surrounding plasma is an area plasma-physics research multitude applications. This paper introduces the octree code pot, microscopic simulator spheroidal dust grain in plasma. pot uses Barnes-Hut treecode algorithm to perform $N$-body simulations electrons and ions vicinity chargeable spheroid, employing also Boris particle-motion integrator Hutchinson's reinjection from SCEPTIC; description implementation all three algorithms provided. We present...
The current theories of macroparticle charging in a plasma are limited to spheres, and unsuitable for the multitude nonspherical objects existing astrophysical, atmospheric, laboratory, fusion plasmas. This paper extends most widely used spherical theory, orbit motion spheroids and, as such, provides comprehensive study plasma. theory is shown be reasonable approximation considerable range spheroids. However, electric potential highly elongated can almost twice value. Furthermore, total...
Plasma-surface interactions are ubiquitous in the field of plasma science and technology. Much physics these can be captured with a simple model comprising cold ion fluid electrons which satisfy Boltzmann relation. However, this permits analytical solutions very limited number cases. This paper presents versatile robust numerical implementation for arbitrary surface geometries cartesian axisymmetric cylindrical coordinates. Specific examples surfaces sinusoidal corrugations, trenches,...
Abstract Maintaining the stability of a liquid surface in contact with plasma is crucial importance range industrial and fusion applications. The most fundamental feature plasma-surface interaction, formation highly-charged sheath region, has been neglected from majority previous studies plasma-liquid interactions. This paper considers effect electric field on ejection micron-scale droplets bubbles bursting at surface. A numerical simulation method, based ideal electrohydrodynamic model,...
The ever-decreasing size of electron sources, many which are now on the nanometer scale, has prompted several recent theoretical studies emission from highly curved surfaces. These have naturally focused grounded tips and spheres, as is appropriate for most nanoelectronic devices, found significant corrections planar theories. However numerous examples nongrounded nanoscale emitters exist in form hot and/or charged dust, droplets aerosols a variety industrial, laboratory, natural...
The Murphy-Good methodology has been followed in order to find the field and thermal emission current densities from an earthed conducting nanosphere. regions of validity resulting expressions have found F-T parameter space. This can be straightforwardly applied other one-dimensional problems, such as isolated spheres or planar electrodes contact with plasmas, by formulating barrier-form correction factor terms parameters which are independent W so that expansions Eqs. 9 14 remain unchanged.