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Found 9 entries in the Bibliography.
Showing entries from 1 through 9
The Kinetic Expansion of Solar-wind Electrons: Transport Theory and Predictions for the Very Inner Heliosphere
We propose a transport theory for the kinetic evolution of solar-wind electrons in the heliosphere. We derive a gyro-averaged kinetic transport equation that accounts for the spherical expansion of the solar wind and the geometry of the Parker spiral magnetic field. To solve our three-dimensional kinetic equation, we develop a mathematical approach that combines the Crank-Nicolson scheme in velocity space and a finite-difference Euler scheme in configuration space. We initialize our model with isotropic electron distribution ...
Jeong, Seong-Yeop; Verscharen, Daniel; Vocks, Christian; Abraham, Joel; Owen, Christopher; Wicks, Robert; Fazakerley, Andrew; Stansby, David; Ber\vci\vc, Laura; Nicolaou, Georgios; Rueda, Jeffersson; Bakrania, Mayur;
Published by: \apj Published on: mar
YEAR: 2022   DOI: 10.3847/1538-4357/ac4805
Parker Data Used; Solar wind; Space plasmas; Heliosphere; Theoretical models; 1534; 1544; 711; 2107; Physics - Space Physics
Radial Evolution of Thermal and Suprathermal Electron Populations in the Slow Solar Wind from 0.13 to 0.5 au: Parker Solar Probe Observations
We develop and apply a bespoke fitting routine to a large volume of solar wind electron distribution data measured by Parker Solar Probe over its first five orbits, covering radial distances from 0.13 to 0.5 au. We characterize the radial evolution of the electron core, halo, and strahl populations in the slow solar wind during these orbits. The fractional densities of these three electron populations provide evidence for the growth of the combined suprathermal halo and strahl populations from 0.13 to 0.17 au. Moreover, the ...
Abraham, Joel; Owen, Christopher; Verscharen, Daniel; Bakrania, Mayur; Stansby, David; Wicks, Robert; Nicolaou, Georgios; Whittlesey, Phyllis; Rueda, Jeffersson; Jeong, Seong-Yeop; Ber\vci\vc, Laura;
Published by: \apj Published on: jun
YEAR: 2022   DOI: 10.3847/1538-4357/ac6605
Parker Data Used; The Sun; Heliosphere; Plasma physics; Solar wind; 1693; 711; 2089; 1534; Astrophysics - Solar and Stellar Astrophysics; Astrophysics - Earth and Planetary Astrophysics; Physics - Plasma Physics; Physics - Space Physics
The Stability of the Electron Strahl against the Oblique Fast-magnetosonic/Whistler Instability in the Inner Heliosphere
We analyze the micro-kinetic stability of the electron strahl in the solar wind depending on heliocentric distance. The oblique fast- magnetosonic/whistler (FM/W) instability has emerged in the literature as a key candidate mechanism for the effective scattering of the electron strahl into the electron halo population. Using data from the Parker Solar Probe (PSP) and Helios, we compare the measured strahl properties with the analytical thresholds for the oblique FM/W instability in the low- and high-\ensuremath\beta $_\ensur ...
Jeong, Seong-Yeop; Abraham, Joel; Verscharen, Daniel; Ber\vci\vc, Laura; Stansby, David; Nicolaou, Georgios; Owen, Christopher; Wicks, Robert; Fazakerley, Andrew; Rueda, Jeffersson; Bakrania, Mayur;
Published by: \apjl Published on: feb
YEAR: 2022   DOI: 10.3847/2041-8213/ac4dff
Parker Data Used; 1534; 1544; 711; Astrophysics - Solar and Stellar Astrophysics; Physics - Plasma Physics; Physics - Space Physics
Thermal Energy Budget of Electrons in the Inner Heliosphere: Parker Solar Probe Observations
We present an observational analysis of the electron thermal energy budget using data from Parker Solar Probe. We use the macroscopic moments, obtained from our fits to the measured electron distribution function, to evaluate the thermal energy budget based on the second moment of the Boltzmann equation. We separate contributions to the overall budget from reversible and irreversible processes. We find that an irreversible thermal energy source must be present in the inner heliosphere over the heliocentric distance range fro ...
Abraham, Joel; Verscharen, Daniel; Wicks, Robert; Rueda, Jeffersson; Owen, Christopher; Nicolaou, Georgios; Jeong, Seong-Yeop;
Published by: \apj Published on: dec
YEAR: 2022   DOI: 10.3847/1538-4357/ac9fd8
Parker Data Used; The Sun; Solar wind; Heliosphere; Plasma physics; 1693; 1534; 711; 2089; Astrophysics - Solar and Stellar Astrophysics; Physics - Geophysics; Physics - Plasma Physics; Physics - Space Physics
Evolving solar wind flow properties of magnetic inversions observed by Helios
Macneil, Allan; Owens, Mathew; Wicks, Robert; Lockwood, Mike;
Published by: \mnras Published on: 03/2021
YEAR: 2021   DOI: 10.1093/mnras/staa3983
Sun: heliosphere; Sun: magnetic fields; Solar wind; Astrophysics - Solar and Stellar Astrophysics; Physics - Space Physics
Polytropic Behavior of Solar Wind Protons Observed by Parker Solar Probe
A polytropic process describes the transition of a fluid from one state to another through a specific relationship between the fluid density and temperature. The value of the polytropic index that governs this relationship determines the heat transfer and the effective degrees of freedom during a specific process. In this study, we analyze\ solar\ wind proton plasma measurements, obtained by the Faraday cup instrument on board the\ Parker\ Solar\ Probe. We examine the large-scale variations of the ...
Nicolaou, Georgios; Livadiotis, George; Wicks, Robert; Verscharen, Daniel; Maruca, Bennett;
Published by: The Astrophysical Journal Published on: 09/2020
YEAR: 2020   DOI: 10.3847/1538-4357/abaaae
Parker Data Used; parker solar probe; Solar Physics; Solar Probe Plus; Solar wind; Space plasmas
The evolution of inverted magnetic fields through the inner heliosphereABSTRACT
Local inversions are often observed in the heliospheric magnetic field (HMF), but their origins and evolution are not yet fully understood. Parker Solar Probe has recently observed rapid, Alfv\ enic, HMF inversions in the inner heliosphere, known as \textquoterightswitchbacks\textquoteright, which have been interpreted as the possible remnants of coronal jets. It has also been suggested that inverted HMF may be produced by near-Sun interchange reconnection; a key process in mechanisms proposed for slow solar wind release. ...
Macneil, Allan; Owens, Mathew; Wicks, Robert; Lockwood, Mike; Bentley, Sarah; Lang, Matthew;
Published by: Monthly Notices of the Royal Astronomical Society Published on: 04/2020
YEAR: 2020   DOI: 10.1093/mnras/staa951
Astrophysics - Solar and Stellar Astrophysics; magnetic fields; parker solar probe; Physics - Space Physics; plasmas; Solar Probe Plus; Solar wind; Sun: heliosphere
The Fluid-like and Kinetic Behavior of Kinetic Alfv\ en Turbulence in Space Plasma
Kinetic Alfv\ en waves (KAWs) are the short-wavelength extension of the magnetohydrodynamics Alfv\ en-wave branch in the case of highly oblique propagation with respect to the background magnetic field. Observations of space plasma show that small-scale turbulence is mainly KAW-like. We apply two theoretical approaches, a collisional two-fluid theory and a collisionless linear kinetic theory, to obtain predictions for the KAW polarizations depending on\ β\ p\ (the ratio of the proton th ...
Wu, Honghong; Verscharen, Daniel; Wicks, Robert; Chen, Christopher; He, Jiansen; Nicolaou, Georgios;
Published by: The Astrophysical Journal Published on: 01/2019
YEAR: 2019   DOI: 10.3847/1538-4357/aaef77
magnetohydrodynamics: MHD; plasmas; solar-terrestrial relations; turbulence; waves; Physics - Space Physics; Astrophysics - Solar and Stellar Astrophysics; Physics - Plasma Physics
AIP Conference ProceedingsTemperature anisotropy instabilities; combining plasma and magnetic field data at different distances from the Sun
We present a new data analysis method enabling the observation of magnetic field fluctuations associated with temperature anisotropy instabilities using the Ulysses spacecraft. The movement of the spacecraft away from the Sun causes the observed plasma conditions, turbulent fluctuation amplitude, magnetic field strength and important physical scales to change. We normalize wavelet power spectra of the magnetic field using local values for the proton gyroscale and large scale magnetic field fluctuation amplitude to remove ...
Wicks, Robert; Matteini, Lorenzo; Horbury, Timothy; Hellinger, Petr; Roberts, Aaron;
Published by: Published on: 07/2013
YEAR: 2013   DOI: 10.1063/1.4811048
96.50.Ci; 96.60.Hv; 96.60.Tf; 96.60.Vg; astrophysical plasma; data analysis; parker solar probe; plasma instability; solar magnetism; Solar Probe Plus; solar spectra; Solar wind; Solar wind plasma; sources of solar wind; wavelet transforms