A5067087293- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Magnetic confinement fusion research
- Radio Astronomy Observations and Technology
- Earthquake Detection and Analysis
- Geomagnetism and Paleomagnetism Studies
- Gamma-ray bursts and supernovae
- Seismic Waves and Analysis
- Laser-Plasma Interactions and Diagnostics
- Astro and Planetary Science
- IoT and GPS-based Vehicle Safety Systems
- Particle Detector Development and Performance
- Astrophysics and Cosmic Phenomena
- Particle Accelerators and Free-Electron Lasers
- Geophysics and Gravity Measurements
- Plasma Diagnostics and Applications
- Solar Radiation and Photovoltaics
- Atmospheric aerosols and clouds
- Stellar, planetary, and galactic studies
- solar cell performance optimization
- Geophysics and Sensor Technology
- Plasma Applications and Diagnostics
- Semiconductor Quantum Structures and Devices
- Ocean Waves and Remote Sensing
University of Warwick
2013-2021
Coventry (United Kingdom)
2021
University of Reading
2017
University of Glasgow
2012-2014
Context. Quasi-periodic pulsations (QPP) of the electromagnetic radiation emitted in solar and stellar flares are often detected microwave, white light, X-ray, gamma-ray bands. Mechanisms for QPP intensively debated literature. Previous studies revealed that may manifest non-linear, non-stationary and, perhaps, multi-modal processes operating flares.
Abstract Radiation belt codes evolve electron dynamics due to resonant wave‐particle interactions. It is not known how best incorporate in the case of a wave power spectrum that varies considerably on “sub‐grid” timescale shorter than computational time‐step radiation model Δ t RBM , particularly if amplitude reaches high values. Timescales associated with growth rate thermal instabilities are very short, and typically much . We use kinetic code study interactions whistler‐mode waves...
Non-thermal electrons accelerated in the solar corona can produce intense coherent radio emission, known as type III bursts. This emission is often observed from hundreds of MHz down to tens kHz range interplanetary space. It involves a chain physical processes generation Langmuir waves nonlinear wave-wave interaction. We develop self-consistent model calculate non-thermal electron population over large frequency range, including effects transport, wave-electron interaction, evolution due...
Abstract Decades of in situ observations whistler mode waves Earth's magnetosphere reveal that there is frequently a gap the spectral power at around half local electron gyrofrequency. Recent theoretical and kinetic simulation studies have suggested arises due to presence temperature anisotropy both “warm” “hot” population, leading two separate (and independent) regions wave growth frequency space. We present two‐dimensional plasma simulations using powerful EPOCH (Extendable PIC Open...
Abstract Test particle codes indicate that electron dynamics due to interactions with low amplitude incoherent whistler mode‐waves can be adequately described by quasi‐linear theory. However there is significant evidence indicating higher waves cause not using Using the method was introduced in Allanson et al. (2019, https://doi.org/10.1029/2019JA027088 ), we track dynamical response of electrons whistler‐mode waves, across all energy and pitch angle space. We conduct five experiments each...
This document provides detailed information on the status of Advanced and Novel Accelerators techniques describes steps that need to be envisaged for their implementation in future accelerators, particular high energy physics applications. It complements overview prepared update European Strategy particle physics, a description field. The scientific priorities community are described each technique acceleration able achieve accelerating gradient GeV~range or above. ALEGRO working group...
Context. High-energy electrons accelerated during solar flares are abundant in the corona and interplanetary space. Commonly, number energy of non-thermal at Sun is estimated through hard X-ray (HXR) spectral observations (e.g. RHESSI) a single-particle collisional approximation.
Quasilinear theory has long been used to treat the problem of a weak electron beam interacting with plasma and generating Langmuir waves. Its extension weak-turbulence treats resonant interactions these waves other wave modes, in particular, ion-sound These are strongly damped equal ion temperatures, as sometimes seen in, for example, solar corona wind. Weak turbulence is derived damping limit, term describing then added. In this paper, we use EPOCH particle-in-cell code numerically test...
The evolution of a solar flare accelerated non-thermal electron population and associated plasma emission is considered in collisional inhomogeneous plasma. Non-thermal electrons collisionally evolve to become unstable generate Langmuir waves, which may lead intense radio emission. We self-consistently simulated the relaxation electrons, wave-particle interactions, non-linear wave with density fluctuations. Additionally, we scattering, decay, coalescence waves produce at fundamental or...
Abstract Of particular interest for radio and hard X‐ray diagnostics of accelerated electrons during solar flares is the understanding basic nonlinear mechanisms regulating relaxation electron beams propagating in turbulent plasmas. In this work, it shown that addition to scattering beam electrons, beam‐generated Langmuir waves via instance mode coupling can also result broadening wave‐particle resonance. We obtain a resonance‐broadened version weak turbulence theory with ion sound modes....
Non-thermal electron populations are observed throughout the heliosphere. The relaxation of an beam is known to produce Langmuir waves which, in turn, may substantially modify distribution function. As refracted by background density gradients and as solar heliospheric plasma naturally perturbed with various levels inhomogeneity, interaction non-thermal electrons inhomogeneous plasmas important topic. We investigate role played ambient fluctuations on beam-plasma relaxation, focusing effect...
Abstract Using a particle‐in‐cell code, we study the diffusive response of electrons due to wave‐particle interactions with whistler‐mode waves. The relatively simple configuration field‐aligned waves in cold plasma is used order benchmark our novel method, and compare previous works that different modelling technique. In this boundary‐value problem, incoherent are excited at domain boundary, then propagate through ambient plasma. Electron diffusion characteristics directly extracted from...
The fields of solar radiophysics and system radio physics, or heliophysics, will benefit immensely from an instrument with the capabilities projected for SKA.Potential applications include interplanetary scintillation (IPS), radio-burst tracking, spectral imaging a superior sensitivity.These provide breakthrough new insights results in topics fundamental importance, such as physics impulsive energy releases, magnetohydrodynamic oscillations turbulence, dynamics post-eruptive processes,...
This thesis considers the propagation of accelerated electron beams in plasma. We consider wave particle interactions these undergo which cause their evolution, effects plasma density inhomogeneities on interactions, and this may have production hard X-ray radio emission by beam. ...
The fields of solar radiophysics and system radio physics, or heliophysics, will benefit immensely from an instrument with the capabilities projected for SKA. Potential applications include interplanetary scintillation (IPS), radio-burst tracking, spectral imaging a superior sensitivity. These provide breakthrough new insights results in topics fundamental importance, such as physics impulsive energy releases, magnetohydrodynamic oscillations turbulence, dynamics post-eruptive processes,...