A5032879757- Magnetic confinement fusion research
- Fusion materials and technologies
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Metal and Thin Film Mechanics
- Laser-Plasma Interactions and Diagnostics
- Plasma Diagnostics and Applications
- Diamond and Carbon-based Materials Research
- Solar and Space Plasma Dynamics
- Astro and Planetary Science
- Viral Infections and Vectors
- Advanced MEMS and NEMS Technologies
- Copper Interconnects and Reliability
- Magnetic and transport properties of perovskites and related materials
- Health Systems, Economic Evaluations, Quality of Life
- Advanced Surface Polishing Techniques
- Advanced Condensed Matter Physics
- Advanced Fiber Optic Sensors
- Particle accelerators and beam dynamics
- Pneumocystis jirovecii pneumonia detection and treatment
- Nuclear reactor physics and engineering
- Semiconductor materials and devices
- Laser-induced spectroscopy and plasma
- Transition Metal Oxide Nanomaterials
- Adaptive optics and wavefront sensing
Max Planck Institute for Plasma Physics
2024
United Kingdom Atomic Energy Authority
2023-2024
Culham Science Centre
2023-2024
Culham Centre for Fusion Energy
2022-2024
University of Liverpool
2019-2023
Boston Micromachines (United States)
2013
Northeastern University
2008
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...
Abstract In this work, we provide the first 2D spatially resolved description of radiative detachment in MAST-U Super-X L-mode divertor plasmas. The magnetic configuration was designed to achieve reduced heat- and particle loads at target compared conventional exhaust solutions. We use filtered camera imaging reconstruct emissivity profiles poloidal plane for multiple atomic molecular emission lines bands. A set deuterium fuelling scans is discussed that, together, span attached deeply...
Abstract The integration of good core and edge/pedestal confinement with strong dissipation heat particles in the divertors is a significant challenge for development fusion energy. Alternative divertor configurations offer potential advantages by broadening operational space where device can operate detached acceptable power exhaust. First results from MAST Upgrade are presented high mode experiments outer Super-X configuration, showing that naturally detach when formed no discernible...
Abstract This paper shows first quantitative analysis of the detachment processes in MAST Upgrade Super-X divertor (SXD). We identify an unprecedented impact plasma-molecular interactions involving molecular ions (likely <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mi>D</mml:mi> <mml:mn>2</mml:mn> <mml:mo>+</mml:mo> </mml:msubsup> </mml:math> ), resulting strong ion sinks (Molecular Activated Recombination—MAR), leading to a reduction target...
The temporal evolution of plasma density and electron temperature in high power impulse magnetron sputtering discharges has been measured using the Langmuir probe laser Thomson scattering techniques. Measurements were performed (nonsimultaneously) at two positions within plasma, low magnetic field strength region on discharge axis trap, for peak densities 450 W cm–2 900 cm−2, respectively. maximum temperatures 6.9 × 1019 m−3 3.7 eV pulse-on time, values decayed to 4.5 1017 0.1 times up 250...
A detailed description of the Langmuir probe system on Mega Ampere Spherical Tokamak Upgrade is presented. The features 850 tile-embedded probes and 40 bespoke electronic modules that each have capability to drive acquire data from up 16 in a time-multiplexed manner. provides spatiotemporal-resolved measurements (1 cm ∼1 ms, respectively) divertor region ion saturation current, electron temperature, floating potential. standard interpretation current-voltage (IV) characteristics apply...
Electron property measurements made by Langmuir probes and laser Thomson scattering have been compared in weakly magnetized plasma conditions using a planar unbalanced magnetron with the aim of assessing accuracy probe diagnostic. The were performed at several locations within magnetic field configuration, null region (≲1 mT) on discharge axis inside last closed flux surface boundary fields up to 33 mT. There was good diagnostic agreement during High Power Impulse Magnetron Sputtering, but...
Abstract Here, we compare the ionization region model (IRM) against experimental measurements of particle densities and electron temperature in a high power impulse magnetron sputtering discharge with tungsten target. The semi-empirical provides volume-averaged temporal variations various species as well energy for particular cathode target material, when given measured current voltage waveforms. results are compared to evolution density determined by Thomson scattering relative neutral ion...
Abstract High resolution <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mtext>D</mml:mtext> </mml:mrow> <mml:mn>2</mml:mn> <mml:mo>∗</mml:mo> </mml:msubsup> </mml:math> Fulcher band spectroscopy was used in the MAST-U divertors during Super-X and (shorter-legged) elongated divertor density ramps with <mml:msub> </mml:msub> fuelling from mid-plane high-field side. In case, upper showed ground state rotational temperatures of molecules...
Plasma detachment involves interactions of the plasma with impurities and neutral particles, leading to significant losses power, momentum, particles. Accurate mapping emissivity in divertor X-point region is essential for assessing relationship between particle flux radiative detachment. The recently validated InfraRed Video Bolometer (IRVB) diagnostic, MAST-U enables this higher spatial resolution than more established methods like resistive bolometers. In previous preliminary work,...
Two new MEMS deformable mirrors have been designed and fabricated, one having a continuous facesheet with an active aperture of 20mm 2040 actuators the other, similarly sized segmented tip tilt piston DM containing 1021 elements 3063 actuators. The surface figures, electro mechanical performances, actuator yield these devices, statistical information, are reported here. distributions measurements directly illustrate variance Boston Micromachines mirrors. Measurements figure were also...
First snowflake (SF) divertor experiments in the MAST-U tokamak demonstrated steady-state snowflake-plus configurations 450 kA ohmic L-mode plasmas. The SF configuration features a second poloidal field (PF) null region close by or overlapping with main X-point. resulting low PF and two additional legs (strike points) may lead to power particle flux sharing via hypothesized convective cell, increased plasma-wetted area radiation. free-boundary Grad–Shafranov equilibrium code FIESTA was used...
In beam theory, constraints can be classified as fixed/pinned depending on whether the rotational stiffness of support is much greater/less than freestanding portion. For intermediate values support, boundary conditions must account for finite constraint. many applications, particularly in microelectromechanical systems and nanomechanics, exist only one side beam. such cases, it may appear at first that same constraint hold. However, purpose this paper to demonstrate even if perfectly bonded...
2D electron density profiles obtained from coherence imaging spectroscopy in different MAST-U divertor conditions are compared. The data includes variations of strike point position, core density, and heating power. improved performance the long-legged divertors results a lower particle flux at target compared to configurations with smaller major radius, while also being characterized by temperatures deeper detachment. Comparisons against SOLPS simulations generally show good agreement...
During detachment, a buffer of neutral atoms and molecules builds up between the target ionising plasma. Collisions plasma play an important role in detachment process. Studies plasma-molecular kinetics indicate that gas temperature is increased during for wide range conditions on MAST-U TCV tokamaks. This related to $\mathrm{D}_2$ lifetime leading more plasma-molecule collisions raise molecular temperature. Such subsequently result significant power momentum losses divertor detachment....
This paper shows first quantitative analysis of the detachment processes in MAST Upgrade Super-X divertor (SXD). We identify an unprecedented impact plasma-molecular interactions involving molecular ions (likely $D_2^+$), resulting strong ion sinks (Molecular Activated Recombination - MAR), leading to a reduction target flux. The MAR exceed sources before electron-ion recombination (EIR) starts occur, suggesting that significant ionisation occurs outside chamber. In EIR region, $T_e \ll 0.2$...
$RE$NiO$_3$ is a negative charge transfer energy system and exhibits temperature-driven metal-insulator transition (MIT), which also accompanied by bond disproportionation (BD) transition. In order to explore how hole doping affects the BD transition, we have investigated electronic structure of single-crystalline thin films Nd$_{1-x}$Ca$_x$NiO$_3$ synchrotron based experiments {\it ab-initio} calculations. For small value $x$, find that doped holes are localized on one or more Ni sites...