F. Spanier
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View article: Calorimetric wire detector for measurement of atomic hydrogen beams
Calorimetric wire detector for measurement of atomic hydrogen beams Open
A calorimetric detector for minimally disruptive measurements of atomic hydrogen beams is described. The calorimeter measures heat released by the recombination of hydrogen atoms into molecules on a thin wire. As a demonstration, the angul…
View article: KARL -- A Monte Carlo model for atomic and molecular processes in the tritium atmosphere of the KATRIN experiment
KARL -- A Monte Carlo model for atomic and molecular processes in the tritium atmosphere of the KATRIN experiment Open
A new parallelized simulation code is presented, which uses a Monte Carlo method to determine particle spectra in the KATRIN source. Reaction chains are generated from the decay of tritium within the source. The code includes all relevant …
View article: Dynamics of Magnetic Evaporative Beamline Cooling for Preparation of Cold Atomic Beams
Dynamics of Magnetic Evaporative Beamline Cooling for Preparation of Cold Atomic Beams Open
The most sensitive direct neutrino mass searches today are based on measurement of the endpoint of the beta spectrum of tritium to infer limits on the mass of the unobserved neutrino. To avoid the smearing associated with the distribution …
View article: Calorimetric Wire Detector for Measurement of Atomic Hydrogen Beams
Calorimetric Wire Detector for Measurement of Atomic Hydrogen Beams Open
A calorimetric detector for minimally disruptive measurements of atomic hydrogen beams is described. The calorimeter measures heat released by the recombination of hydrogen atoms into molecules on a thin wire. As a demonstration, the angul…
View article: Parametrization of coefficients for sub-grid modeling of pitch-angle diffusion in global magnetospheric hybrid-Vlasov simulations
Parametrization of coefficients for sub-grid modeling of pitch-angle diffusion in global magnetospheric hybrid-Vlasov simulations Open
Sub-grid models are key tools to accurately describe the physical processes at play in a system when high-resolution simulations are not feasible. We previously developed a sub-grid model for pitch-angle diffusion in hybrid-Vlasov simulati…
View article: Particle-in-cell Simulations of Mildly Relativistic Outflows in Kilonova Emissions
Particle-in-cell Simulations of Mildly Relativistic Outflows in Kilonova Emissions Open
The electromagnetic emission from neutron star mergers is comprised of multiple components. Synchrotron emission from the disk-powered jet and thermal emission from the merger ejecta (powered by a variety of sources) are among the most stu…
View article: Particle In Cell Simulations of Mildly Relativistic Outflows in Kilonova Emissions
Particle In Cell Simulations of Mildly Relativistic Outflows in Kilonova Emissions Open
The electromagnetic emission from neutron star mergers is comprised of multiple components. Synchrotron emission from the disk-powered jet as well as thermal emission from the merger ejecta (powered by a variety of sources) are among the m…
View article: Determination of pitch-angle diffusion coefficient from bi-Maxwellian velocity distribution functions
Determination of pitch-angle diffusion coefficient from bi-Maxwellian velocity distribution functions Open
Pitch-angle diffusion is one of the main processes of isotropisation of ions in the Earth's magnetosheath. It results from the proton cyclotron and mirror instabilities, arising from temperature anisotropy in the magnetosheath, and is gove…
View article: Monte Carlo simulations of the electron — gas interactions in the KATRIN experiment
Monte Carlo simulations of the electron — gas interactions in the KATRIN experiment Open
At the KATRIN experiment, the electron antineutrino mass is inferred from the shape of the β-decay spectrum of tritium. Important systematic effects in the Windowless Gaseous Tritium Source (WGTS) of the experiment include the energy loss …
View article: Subgrid modelling of pitch-angle diffusion for ion-scale waves in a global hybrid-Vlasov simulation
Subgrid modelling of pitch-angle diffusion for ion-scale waves in a global hybrid-Vlasov simulation Open
<p>Numerical simulations play a central role in modern sciences. The trade-off between the accuracy of the physical processes described and the cost of computational resources is often the main limiting factor in these simulations. I…
View article: Determining Pitch-Angle Diffusion Coefficients for Electrons in Whistler Turbulence
Determining Pitch-Angle Diffusion Coefficients for Electrons in Whistler Turbulence Open
Transport of energetic electrons in the heliosphere is governed by resonant interaction with plasma waves, for electrons with sub-GeV kinetic energies specifically with dispersive modes in the whistler regime. In this paper, particle-in-ce…
View article: Monte Carlo simulations of the electron-gas interactions in the KATRIN experiment
Monte Carlo simulations of the electron-gas interactions in the KATRIN experiment Open
At the KATRIN experiment, the electron antineutrino mass is inferred from the shape of the $\beta$-decay spectrum of tritium. Important systematic effects in the Windowless Gaseous Tritium Source (WGTS) of the experiment include the energy…
View article: Determining pitch-angle diffusion coefficients for electrons in whistler turbulence
Determining pitch-angle diffusion coefficients for electrons in whistler turbulence Open
Transport of energetic electrons in the heliosphere is governed by resonant interaction with plasma waves, for for electrons with sub-GeV kinetic energies specifically with dispersive modes in the whistler regime. We have performed Particl…
View article: Determining pitch-angle diffusion coefficients for electrons in whistler\n turbulence
Determining pitch-angle diffusion coefficients for electrons in whistler\n turbulence Open
Transport of energetic electrons in the heliosphere is governed by resonant\ninteraction with plasma waves, for for electrons with sub-GeV kinetic energies\nspecifically with dispersive modes in the whistler regime. We have performed\nPart…
View article: Ion acceleration in non-relativistic quasi-parallel shocks using fully kinetic simulations
Ion acceleration in non-relativistic quasi-parallel shocks using fully kinetic simulations Open
The formation of collisionless shock fronts is an ubiquitous phenomenon in space plasma environments. In the solar wind shocks might accompany coronal mass ejections, while even more violent events, such as supernovae, produce shock fronts…
View article: Scattering of electron holes in the context of ion-acoustic regime
Scattering of electron holes in the context of ion-acoustic regime Open
Mutual collisions between ion-acoustic (IA) solitary waves are studied based on a fully kinetic simulation approach. Two cases, small and large relative velocity, are studied and the effect of trapped electron population on the collision p…
View article: A study of the stability properties of Sagdeev solutions in the ion-acoustic regime using kinetic simulations
A study of the stability properties of Sagdeev solutions in the ion-acoustic regime using kinetic simulations Open
The Sagdeev pseudo-potential approach has been employed extensively in theoretical studies to determine large-amplitude (fully) nonlinear solutions in a variety of multi-species plasmas. Although these solutions are repeatedly considered a…
View article: Analytical treatment of particle motion in circularly polarized slab-mode wave fields
Analytical treatment of particle motion in circularly polarized slab-mode wave fields Open
Wave–particle interaction is a key process in particle diffusion in collisionless plasmas. We look into the interaction of single plasma waves with individual particles and discuss under which circumstances this is a chaotic process, leadi…
View article: Kinetic simulation study of electron holes dynamics during collisions of ion-acoustic solitons
Kinetic simulation study of electron holes dynamics during collisions of ion-acoustic solitons Open
Ion acoustic (IA) solitons are accompanied by vortex-shaped nonlinear structures (e.g. hollows, plateaus or humps) in the electron distribution function, called electron holes, portraying trapped electrons. These structures appear as charg…
View article: Kinetic simulation study of electron holes dynamics during collisions of\n ion-acoustic solitons
Kinetic simulation study of electron holes dynamics during collisions of\n ion-acoustic solitons Open
Ion acoustic (IA) solitons are accompanied by vortex-shaped nonlinear\nstructures (e.g. hollows, plateaus or humps) in the electron distribution\nfunction, called electron holes, portraying trapped electrons. These structures\nappear as ch…
View article: Fully kinetic simulation study of ion-acoustic solitons in the presence of trapped electrons
Fully kinetic simulation study of ion-acoustic solitons in the presence of trapped electrons Open
The nonlinear fluid theory developed by Schamel suggests a modified KdV equation to describe the temporal evolution of ion acoustic (IA) solitons in the presence of trapped electrons. The validity of this theory is studied here by verifyin…
View article: A comment on "Importance of resolving the spectral support of beam-plasma instabilities in simulations" by M. Shalaby et al
A comment on "Importance of resolving the spectral support of beam-plasma instabilities in simulations" by M. Shalaby et al Open
Understanding the physics of beam-plasma systems is of great importance for a large number of astrophysical systems. Recently the validity of particle-in-cell simulations of these systems has been questioned by Shalaby et al. (2017) We ana…
View article: Fully kinetic simulation study of ion-acoustic solitons in the presence of trapped electrons
Fully kinetic simulation study of ion-acoustic solitons in the presence of trapped electrons Open
The nonlinear fluid theory developed by Schamel suggests a modified KdV equation to describe the temporal evolution of ion acoustic (IA) solitons in the presence of trapped electrons. The validity of this theory is studied here by verifyin…
View article: Recovering the Damping Rates of Cyclotron Damped Plasma Waves from Simulation Data
Recovering the Damping Rates of Cyclotron Damped Plasma Waves from Simulation Data Open
Plasma waves with frequencies close to the particular gyrofrequencies of the charged particles in the plasma lose energy due to cyclotron damping. We briefly discuss the gyro-resonance of low frequency plasma waves and ions particularly wi…
View article: Plasma waves as a benchmark problem
Plasma waves as a benchmark problem Open
A large number of wave modes exist in a magnetized plasma. Their properties are determined by the interaction of particles and waves. In a simulation code, the correct treatment of field quantities and particle behaviour is essential to co…
View article: Kinetic-simulation study of propagation of Langmuir-like ionic waves in dusty plasma
Kinetic-simulation study of propagation of Langmuir-like ionic waves in dusty plasma Open
The propagation of ionic perturbations in a dusty plasma is considered through a three-species kinetic simulation approach, in which the temporal evolution of all three elements i.e. electrons, ions and dust particles are followed based on…