A5005335909- Ionosphere and magnetosphere dynamics
- Astro and Planetary Science
- Planetary Science and Exploration
- Dust and Plasma Wave Phenomena
- Laser-induced spectroscopy and plasma
- Earthquake Detection and Analysis
- Solar and Space Plasma Dynamics
- High-pressure geophysics and materials
- Plasma Diagnostics and Applications
- Particle Dynamics in Fluid Flows
- Space Exploration and Technology
- Geomagnetism and Paleomagnetism Studies
- Atomic and Molecular Physics
- Ion-surface interactions and analysis
- Combustion and Detonation Processes
- Atmospheric aerosols and clouds
- Cold Atom Physics and Bose-Einstein Condensates
- Diamond and Carbon-based Materials Research
- Gas Dynamics and Kinetic Theory
- Astrophysics and Star Formation Studies
- Space exploration and regulation
- Transportation Safety and Impact Analysis
- Aeolian processes and effects
- Space Satellite Systems and Control
- Dark Matter and Cosmic Phenomena
Imperial College London
2024
Charles University
2013-2023
Hammersmith Hospital
2010-2022
Imperial College Healthcare NHS Trust
2022
University of Ostrava
2014
Czech Technical University in Prague
1990-2002
Abstract Electric field antennas are capable of detecting dust impacts in different space environment. We analyze the impact signals detected by Cassini Radio and Plasma Wave Science instrument at locations around Saturn compare them with simulated laboratory conditions numerically. The spacecraft potential, size, capacitance impacted element ambient plasma have a strong effect on amplitude shape signals, providing important clues to understanding signal generation mechanism. voltage antenna...
Abstract. The electric and magnetic field instrument suite FIELDS on board the NASA Parker Solar Probe radio plasma waves RPW ESA Orbiter mission that explore inner heliosphere are sensitive to signals generated by dust impacts. Dust impacts have been observed using antennas spacecraft since 1980s method was recently used with a number of space missions derive fluxes. Here, we consider details impacts, subsequent development impact how it produces measured signals. We describe empirical...
We present an investigation of the dust distribution in Saturn’s rings based on hypervelocity impacts observed by Cosmic Dust Analyzer (CDA) and Radio Plasma Wave Science (RPWS) instrument board Cassini spacecraft. The create spiky signals electric field waveforms that are used to determine profiles impact count rate, mass, evaluated wave power spectral density (PSD) during ring crossings. Information about composition velocity is extracted from available CDA data. calculated...
This study investigates the distribution of dust in Saturn’s rings, analyzing impact signals detected by Radio and Plasma Wave Science (RPWS) instrument aboard Cassini spacecraft. Over its 13-year mission, electric field antennas RPWS registered sharp spiky caused hypervelocity impacts. Data from multiple ring crossings were analyzed using power spectral method. The vertical profiles amplitudes determined radial distances 2.45 to 4.5 Rs center Saturn. results show spatial density...
Dust in the interplanetary space and around planets can be observed by specialized detectors that allow determination of many parameters like velocity, mass or even composition registered dust grains but principal disadvantage such is their small geometrical factor. On other hand, are impacting whole spacecraft body these impacts influence potential various mechanisms thus used for detection electric antennas. The field instruments register as short pulses resulting from interplay between...
This paper deals with the influence of experimental conditions on properties melamine formaldehyde resin particles. Motivation for this study was fact that many laboratories and experimenters use these particles as samples dust plasma investigations. We have found mass grains decreases during long-time exposure in vacuum. decrease proceeds much faster if temperature is increased.
ABSTRACT Interaction between the lunar surface and solar UV radiation surrounding plasma environment leads to its charging by different processes like photoemission, collection of charged particles, or secondary electron emission (SEE). Whereas photoemission depends only on angle direction Sun varies slowly, parameters can change rapidly as Moon orbits around Earth. This paper presents numerical simulations one pass through magnetospheric tail including real measured THEMIS an input. The...
Abstract We present an analysis of 1‐year data dust impacts observed on two the Earth‐orbiting Magnetospheric Multiscale mission (MMS) spacecraft. The impact signals were identified in observations electric field probes and registered simultaneously by monopole dipole configurations instrument. This unique setup allows us to reliably identify changes spacecraft potential as candidates for impacts. a detailed study properties pulses generated show influence local plasma environment...
Abstract SARS-CoV-2 infection, and resulting disease, COVID-19, has a high mortality amongst patients with haematological malignancies. Global vaccine rollouts have reduced hospitalisations deaths, but efficacy in malignancies is known to be reduced. The UK-strategy offered third, mRNA-based, as an extension the primary course these patients. MARCH database retrospective observational study of serological responses blood disorders. Here we present data on 381 By comparison healthy controls,...
The secondary electron emission is believed to play an important role for the dust charging at and close lunar surface. However, our knowledge of properties results from model calculations rather rare laboratory investigations. present paper reports measurements surface potential on Lunar Highlands Type regolith simulants with sizes between 0.3 3 μm in beam energy below 700 eV. This investigation focused a low-energy part, i.e., ⩽100 We found that equilibrium this simulant does not depend...
Abrupt changes of the relative He abundance in solar wind are usually attributed to encounters with boundaries dividing streams from different sources corona. This paper presents a systematic study fast variations that supports idea majority these on short timescales (3–30 s) generated by in-transit turbulence is probably driven speed difference between ion species. contributes heating and leads correlation temperature abundance.
The detection parameters of a small thermal neutron detector based on PN junction Si diode complete with 6LiF converter are described. Overall dimensions basically limited only by the wafer and packing used. Aluminium polyethylene were utilised as main construction materials. Responses to different kinds radiations measured. Efficiency for neutrons is selectable approximately in range between 5 x 10-4 3 10-2 pulses per neutron.cm-2. fast (e.g. from 241Am-Be source) was determined be times lower.
The present paper reviews our latest, and brings several new, results on charging of dust grains various materials sizes. Charging processes in space their influence the dynamics are analyzed laboratory simulations secondary emission, field ion electron emissions, sputtering. Single micrometre-sized grain clusters stored a hyperbolic quadrupole under ultra-high vacuum conditions for long time periods. charge state its evolution recorded while is exposed to or beams energies fluxes. emission...
Abstract The Radio and Plasma Wave Science instrument on Cassini has observed fewer than expected dust particle impacts during the mission's Grand Finale orbits. relatively strong magnetic field in close vicinity of planet been suggested to affect intensity impact generated signals. A laboratory investigation is performed using particles accelerated ≥20 km/s speed impacting onto a previously developed model spacecraft antennas. external by two sets coils. recorded antenna waveforms are...
The dust grain charge in an electron beam is given by a difference numbers of electrons that fall onto the and those leaving it. Electrons with energies exceeding 1 keV can penetrate through submicron-sized grains. If small enough, yield these reaches unity but they leave part their energy inside this excites secondary electrons. paper presents hybrid Monte Carlo code simulates paths primary spherical provides scattered spectrum as function size material. This based on Richterov\'a et al....
Dust production and its transport into the core plasma is an important issue for magnetic confinement fusion. grains are charged by various processes, such as collection of particles electron emissions, their charge influences dynamics dust. This paper presents results calculations surface potential dust in a Maxwellian plasma. Our include charging balance secondary emission (SEE) from The numerical model that we have used accounts influence backscattered electrons takes account effects...
Abstract Dust impact detection by electric field instruments is a well-established technique. On the other hand, not all aspects of signal generation dust impacts are completely understood. We present study events related to on spacecraft body detected probes operating simultaneously in monopole (probe-to-spacecraft potential measurement) and dipole (probe-to-probe configurations Earth-orbiting Magnetospheric Multiscale mission spacecraft. This unique measurement allows us investigate...
Secondary emission from metal surfaces is well described by the theory of Sternglass. His and resulting "universal" curve can be applied for planar uncharged in an energy range tens electronvolts to several kiloelectronvolts. However, space dust composed silicates, ice, graphite, i.e., nonconducting materials. Their are highly curved, they usually charged nonnegligible potentials. Since previous attempts describe size effect on properties succeeded only partly, we have used original...
We present a combined experimental and simulation study of the charging spherical gold samples by an electron beam in $0.15--10\phantom{\rule{0.3em}{0ex}}\mathrm{keV}$ range energies. Experiments on grains with diameters order ${10}^{\ensuremath{-}6}\phantom{\rule{0.3em}{0ex}}\mathrm{m}$ show that charge (or surface potential) levitating guadrupole trap is function both grain diameter energy. Monte Carlo simulations reveal increase potential energy for fixed or decrease given are connected...