A5048881817- Lightning and Electromagnetic Phenomena
- Atomic and Molecular Physics
- High voltage insulation and dielectric phenomena
- Muon and positron interactions and applications
- Electrical Fault Detection and Protection
- Particle accelerators and beam dynamics
- Vacuum and Plasma Arcs
- Quantum, superfluid, helium dynamics
- Dark Matter and Cosmic Phenomena
- Power Transformer Diagnostics and Insulation
- Nuclear physics research studies
- Ultrasonics and Acoustic Wave Propagation
- Structural Health Monitoring Techniques
- Cold Atom Physics and Bose-Einstein Condensates
- Electrostatic Discharge in Electronics
- Quantum Chromodynamics and Particle Interactions
- Structural Response to Dynamic Loads
- Particle Accelerators and Free-Electron Lasers
- Quantum and Classical Electrodynamics
- Advanced Measurement and Detection Methods
- Smart Materials for Construction
- Non-Destructive Testing Techniques
- Mechanical Behavior of Composites
- Laser-Plasma Interactions and Diagnostics
- Thermal Analysis in Power Transmission
Cardiff University
2015-2024
Swansea University
2004-2009
University of Wales
2004-2009
We have developed a new method, based on the ballistic transfer of preaccumulated plasmas, to obtain large and dense positron plasmas in cryogenic environment. The method involves transferring emanating from region with low magnetic field (0.14 T) relatively high pressure (10(-9) mbar) into 15 K Penning-Malmberg trap immersed 3 T base better than 10(-13) mbar. achieved accumulation rate is more one half orders magnitude higher previous most efficient UHV compatible scheme. Subsequent...
Electrical processes such as lightning and transient luminous events (TLEs) are important drivers of chemical in planetary atmospheres, including potentially facilitating the formation prebiotic molecules. The numerous extrasolar planets discovered present a huge diversity environmental conditions to explore possible emergence electrical processes. To this end, we adapt general circulation models simulate these exoplanet atmospheres study potential Here, results from simulations tidally...
To better understand lightning interactions with the atmosphere, a high-speed (streak) spectrograph was used to characterise various high voltage impulses representing lightning. A Marx generator produce 1.2/50 μs impulses, according IEC 60060 standard, ranging from 60 kV 160 kV. The atomic emission spectrum captured using streak system at resolutions of 0.35 μs/pixel 0.14 μs/pixel. Spectral data were first recorded over broad range 250 990 nm, covering part...
Antihydrogen is formed when antiprotons are mixed with cold positrons in a nested Penning trap. We present experimental evidence, obtained using our antihydrogen annihilation detector, that the spatial distribution of emerging atoms independent positron temperature and axially enhanced. This indicates before thermal equilibrium plasma. result has important implications for trapping spectroscopy antihydrogen.
The objective of this study was to adapt ultrasonic and radiographic techniques for the inspection wind turbine blades compare obtainedresults. measurements performed show that are capable reliably detecting a number structural defects within blade. adapted air-coupled technique, using Lamb waves, proved be most promising in terms implementation as it only requires access one side. However, novel combination contact pulse-echo immersion moving container water identified shape size better....
Cold antihydrogen atoms were produced by mixing cold samples of antiprotons and positrons. The temperature the positron plasma was increased controlled radio-frequency (RF) heating, production measured. Formation is observed to decrease with but a simple power law scaling not observed. Significant still present at room temperature.
We present evidence showing how antiprotonic hydrogen, the quasistable antiproton (p)-proton bound system, has been synthesized following interaction of antiprotons with molecular ion H2+ in a nested Penning trap environment. From careful analysis spatial distributions annihilation events, is presented for hydrogen production sub-eV kinetic energies states around n=70, and low angular momenta. The slow may be studied using laser spectroscopic techniques.
Abstract Research into residual strength after lightning strike is increasing within the literature. However, standard test methods for measuring compressive strikes do not exist. For first time, a systematic experimental study undertaken to evaluate modifications necessary Compression After Impact (CAI) specimen geometry and jig design induce failure at damage region. Four laboratory generated currents with peak amplitudes ranging from 25 100 kA have been studied. Test set-up were made...
Antihydrogen can be synthesized by mixing antiprotons and positrons in a Penning trap environment. Here an experiment to stimulate the formation of antihydrogen n = 11 quantum state introduction light from CO2 continuous wave laser is described. An overall upper limit 0.8% with 90% C.L. on laser-induced enhancement recombination has been found. This result strongly suggests that radiative contributes negligibly formed experimental conditions used ATHENA Collaboration.
We demonstrate temporally controlled modulation of cold antihydrogen production by periodic RF heating a positron plasma during antiproton-positron mixing in Penning trap. Our observations have established pulsed source atomic antimatter, with rise time about 1 s, and pulse length ranging from 3 to 100 s. Time-sensitive detection diagnostics, both capabilities the ATHENA apparatus, allowed detailed studies pulsing behavior, which turn gave information on dependence process temperature T....
A technique was developed for the comparison of observed emission spectra from lightning current arcs generated through self-breakdown in air and use two types initiation wire, aluminum bronze nichrome, against previously published natural events. spectrograph system used which wavelength light emitted by arc analyzed to derive elemental interactions. impulse up 100 kA applied a hemispherical tungsten electrode configuration allowed effect length be investigated. reference spectrum...
An observation of a clear dependence antihydrogen production on positron plasma shapes is reported. For this purpose control method has been developed combining the rotating-wall technique with mode diagnostic system. With help real-time and nondestructive observations, parameters have optimized. The can be manipulated into wide range (aspect ratio 6.5⩽α≲80) densities (1.5×108⩽n≲7×109cm−3) within short duration (25s) compatible ATHENA cycle.Received 22 April...
A recently developed spectrographic technique was used for the comparison of observed optical emission spectra from self-breakdown in air high current and voltage impulse arcs which are often to represent respective components a natural lightning strike variety studies. These separated as it is practically impossible simultaneously generate both single arc within laboratory. The aspect typically related amount damage does an impacted object can be characterize conductivity properties,...
Lightning is one of the most unpredictable and destructive forces in nature, ensuring protection safety aircraft flight, as well other modes airborne transport, when struck by lightning presents a unique set engineering challenges. In order to progress into new generation conductive carbon composites and/or embedded light-weight systems, further scientific understanding required on mechanisms impact composite aircraft. This paper recalls how modern research has progressed from deducing...
We have investigated an extension of the buffer gas cooling technique to a non-neutral gas. The proposed scheme will allow efficient mass-selective centering ions confined in Penning trap situations where use neutral damping agent is not possible. present paper reviews principle and reports on evidence for sideband antiprotons electron gas, obtained with ATHENA apparatus at CERN's Antiproton Decelerator facility.
In electrical networks, SF6 gas is currently used to insulate high-voltage equipment, however, due its high environmental impact, new alternatives such as CO2 and electronegative mixtures CF3I-CO2 are being trialled replace create a sustainable energy system. A lightning impulse (1.2 μs/50 μs) was approximate the disturbance in network caused by strike helped identify likely streamer leader formations different gases insulating piece of insulated switchgear. this paper, theoretical practical...
This paper outlines preliminary results from a passive optical spectrographic system operating in the ultraviolet to near-infrared range. The was developed at Morgan-Botti Lightning Laboratory, Cardiff University, examine lightning and its interaction with materials, focus on application aerospace grade carbon composites. laboratory complimentary transient light measurement are described. Two studies presented: used obtain data three different arc waveforms, strikes materials; aluminium,...
Due to the destructive impact of lightning, and risk increasing strikes attributed climate change on natural built environment, work has been carried out study temperature light emitted by laboratory generated lightning using non-invasive light-based instrumentation, which will allow optimisation protection. Using spectroscopy, optical emission spectrum a 55 kA arc with copper fuse wire was obtained for study. The results showed radiated in visible infrared range, strong lines seen,...
This paper focuses on the displacement of aluminum plates subjected to forces generated by a lightning current in order compare modelling and experimental results directly. The electromechanical produced during strikes can cause catastrophic damage hence there is need understand performance existing new materials under such extreme conditions improve ability withstand these minimize damage. Half-meter square 2mm thick were struck with range currents from 40kA 100kA. A computer model using...
This paper focuses on modelling the deflection of Carbon Fibre Reinforced Polymer (CFRP) and aluminium panels when subjected to forces generated by a lightning current flowing through them. Accurate quantification CFRP plate under strike is important as this may exacerbate deterioration material compromise its mechanical electrical properties. In order predict accurately, there are several parameters that need be taken into account within an electromechanical model, these include; amplitude...