Found 14 entries in the Bibliography.
Showing entries from 1 through 14
| 2020 |
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Constraining Ion-Scale Heating and Spectral Energy Transfer in Observations of Plasma Turbulence We perform a statistical study of the turbulent power spectrum at inertial and kinetic scales observed during the first perihelion encounter of the Parker Solar Probe. We find that often there is an extremely steep scaling range of the power spectrum just above the ion-kinetic scales, similar to prior observations at 1 A.U., with a power-law index of around -4 . Based on our measurements, we demonstrate that either a significant (\>50 \%) fraction of the total turbulent energy flux is dissipated in this range of scales ... Bowen, Trevor; Mallet, Alfred; Bale, Stuart; Bonnell, J.; Case, Anthony; Chandran, Benjamin; Chasapis, Alexandros; Chen, Christopher; Duan, Die; de Wit, Thierry; Goetz, Keith; Halekas, Jasper; Harvey, Peter; Kasper, J.; Korreck, Kelly; Larson, Davin; Livi, Roberto; MacDowall, Robert; Malaspina, David; McManus, Michael; Pulupa, Marc; Stevens, Michael; Whittlesey, Phyllis; YEAR: 2020 DOI: 10.1103/PhysRevLett.125.025102 Astrophysics - Solar and Stellar Astrophysics; Parker Data Used; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; Solar Probe Plus |
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In-situ Switchback Formation in the Expanding Solar Wind Recent near-Sun solar-wind observations from Parker Solar Probe have found a highly dynamic magnetic environment, permeated by abrupt radial-field reversals, or "switchbacks." We show that many features of the observed turbulence are reproduced by a spectrum of Alfv\ enic fluctuations advected by a radially expanding flow. Starting from simple superpositions of low-amplitude outward-propagating waves, our expanding-box compressible magnetohydrodynamic simulations naturally develop switchbacks because (i) the normalized am ... Squire, J.; Chandran, B.; Meyrand, R.; YEAR: 2020 DOI: 10.3847/2041-8213/ab74e1 Astrophysics - Solar and Stellar Astrophysics; Parker Data Used; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; Solar Probe Plus |
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Sharp Alfv\ enic Impulses in the Near-Sun Solar Wind Measurements of the near-Sun solar wind by the Parker Solar Probe have revealed the presence of large numbers of discrete Alfv\ enic impulses with an anti-sunward sense of propagation. These are similar to those previously observed near 1 au, in high speed streams over the Sun\textquoterights poles and at 60 solar radii. At 35 solar radii, however, they are typically shorter and sharper than seen elsewhere. In addition, these spikes occur in "patches" and there are also clear periods within the same stream when they do no ... Horbury, Timothy; Woolley, Thomas; Laker, Ronan; Matteini, Lorenzo; Eastwood, Jonathan; Bale, Stuart; Velli, Marco; Chandran, Benjamin; Phan, Tai; Raouafi, Nour; Goetz, Keith; Harvey, Peter; Pulupa, Marc; Klein, K.; de Wit, Thierry; Kasper, Justin; Korreck, Kelly; Case, A.; Stevens, Michael; Whittlesey, Phyllis; Larson, Davin; MacDowall, Robert; Malaspina, David; Livi, Roberto; YEAR: 2020 DOI: 10.3847/1538-4365/ab5b15 |
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Cross Helicity Reversals in Magnetic Switchbacks We consider 2D joint distributions of normalized residual energy, σr(s, t), and cross helicity, σc(s, t), during one day of Parker Solar Probe\textquoterights (PSP\textquoterights) first encounter as a function of wavelet scale s. The broad features of the distributions are similar to previous observations made by Helios in slow solar wind, namely well-correlated and fairly Alfv\ enic wind, except for a population with negative cross helicity that is seen at shorter wavelet scales. We show that thi ... McManus, Michael; Bowen, Trevor; Mallet, Alfred; Chen, Christopher; Chandran, Benjamin; Bale, Stuart; Larson, Davin; de Wit, Thierry; Kasper, J.; Stevens, Michael; Whittlesey, Phyllis; Livi, Roberto; Korreck, Kelly; Goetz, Keith; Harvey, Peter; Pulupa, Marc; MacDowall, Robert; Malaspina, David; Case, Anthony; Bonnell, J.; YEAR: 2020 DOI: 10.3847/1538-4365/ab6dce Astrophysics - Solar and Stellar Astrophysics; Parker Data Used; parker solar probe; Physics - Space Physics; Solar Probe Plus |
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The Enhancement of Proton Stochastic Heating in the Near-Sun Solar Wind Stochastic heating (SH) is a nonlinear heating mechanism driven by the violation of magnetic moment invariance due to large-amplitude turbulent fluctuations producing diffusion of ions toward higher kinetic energies in the direction perpendicular to the magnetic field. It is frequently invoked as a mechanism responsible for the heating of ions in the solar wind. Here, we quantify for the first time the proton SH rate Q⊥ at radial distances from the Sun as close as 0.16 au, using measurements from the first tw ... c, Mihailo; Klein, Kristopher; Kasper, Justin; Case, Anthony; Korreck, Kelly; Larson, Davin; Livi, Roberto; Stevens, Michael; Whittlesey, Phyllis; Chandran, Benjamin; Alterman, Ben; Huang, Jia; Chen, Christopher; Bale, Stuart; Pulupa, Marc; Malaspina, David; Bonnell, John; Harvey, Peter; Goetz, Keith; de Wit, Thierry; MacDowall, Robert; YEAR: 2020 DOI: 10.3847/1538-4365/ab527f Astrophysics - Solar and Stellar Astrophysics; Parker Data Used; parker solar probe; Physics - Plasma Physics; Solar Probe Plus |
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The Evolution and Role of Solar Wind Turbulence in the Inner Heliosphere The first two orbits of the Parker Solar Probe spacecraft have enabled the first in situ measurements of the solar wind down to a heliocentric distance of 0.17 au (or 36 R\ ⊙\ \ R⊙ ). Here, we present an analysis of this data to study solar wind turbulence at 0.17 au and its evolution out to 1 au. While many features remain similar, key differences at 0.17 au include increased turbulence energy levels by more than an order of magnitude, a magnetic field spectral index of -3/2 matching that of t ... Chen, C.; Bale, S.; Bonnell, J.; Borovikov, D.; Bowen, T.; Burgess, D.; Case, A.; Chandran, B.; de Wit, Dudok; Goetz, K.; Harvey, P.; Kasper, J.; Klein, K.; Korreck, K.; Larson, D.; Livi, R.; MacDowall, R.; Malaspina, D.; Mallet, A.; McManus, M.; Moncuquet, M.; Pulupa, M.; Stevens, M.; Whittlesey, P.; YEAR: 2020 DOI: 10.3847/1538-4365/ab60a3 Astrophysics - Solar and Stellar Astrophysics; Parker Data Used; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; Solar Probe Plus |
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Ion-scale Electromagnetic Waves in the Inner Heliosphere Understanding the physical processes in the solar wind and corona that actively contribute to heating, acceleration, and dissipation is a primary objective of NASA\textquoterights Parker Solar Probe (PSP) mission. Observations of circularly polarized electromagnetic waves at ion scales suggest that cyclotron resonance and wave-particle interactions are dynamically relevant in the inner heliosphere. A wavelet-based statistical study of circularly polarized events in the first perihelion encounter of PSP demonstrates that t ... Bowen, Trevor; Mallet, Alfred; Huang, Jia; Klein, Kristopher; Malaspina, David; Stevens, Michael; Bale, Stuart; Bonnell, J.; Case, Anthony; Chandran, Benjamin; Chaston, C.; Chen, Christopher; de Wit, Thierry; Goetz, Keith; Harvey, Peter; Howes, Gregory; Kasper, J.; Korreck, Kelly; Larson, Davin; Livi, Roberto; MacDowall, Robert; McManus, Michael; Pulupa, Marc; Verniero, J.; Whittlesey, Phyllis; YEAR: 2020 DOI: 10.3847/1538-4365/ab6c65 Astrophysics - Solar and Stellar Astrophysics; Parker Data Used; parker solar probe; Physics - Space Physics; Solar Probe Plus |
| 2019 |
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Highly structured slow solar wind emerging from an equatorial coronal hole During the solar minimum, when the Sun is at its least active, the solar wind is observed at high latitudes as a predominantly fast (more than 500 kilometres per second), highly Alfv\ enic rarefied stream of plasma originating from deep within coronal holes. Closer to the ecliptic plane, the solar wind is interspersed with a more variable slow wind of less than 500 kilometres per second. The precise origins of the slow wind streams are less certain; theories and observations suggest that they may originate at the tips of ... Bale, S.; Badman, S.; Bonnell, J.; Bowen, T.; Burgess, D.; Case, A.; Cattell, C.; Chandran, B.; Chaston, C.; Chen, C.; Drake, J.; de Wit, Dudok; Eastwood, J.; Ergun, R.; Farrell, W.; Fong, C.; Goetz, K.; Goldstein, M.; Goodrich, K.; Harvey, P.; Horbury, T.; Howes, G.; Kasper, J.; Kellogg, P.; Klimchuk, J.; Korreck, K.; Krasnoselskikh, V.; Krucker, S.; Laker, R.; Larson, D.; MacDowall, R.; Maksimovic, M.; Malaspina, D.; Martinez-Oliveros, J.; McComas, D.; Meyer-Vernet, N.; Moncuquet, M.; Mozer, F.; Phan, T.; Pulupa, M.; Raouafi, N.; Salem, C.; Stansby, D.; Stevens, M.; Szabo, A.; Velli, M.; Woolley, T.; Wygant, J.; YEAR: 2019 DOI: 10.1038/s41586-019-1818-7 |
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Self-induced Scattering of Strahl Electrons in the Solar Wind We investigate the scattering of strahl electrons by microinstabilities as a mechanism for creating the electron halo in the solar wind. We develop a mathematical framework for the description of electron-driven microinstabilities and discuss the associated physical mechanisms. We find that an instability of the oblique fast-magnetosonic/whistler (FM/W) mode is the best candidate for a microinstability that scatters strahl electrons into the halo. We derive approximate analytic expressions for the FM/W instability thresho ... Verscharen, Daniel; Chandran, Benjamin; Jeong, Seong-Yeop; Salem, Chadi; Pulupa, Marc; Bale, Stuart; YEAR: 2019 DOI: 10.3847/1538-4357/ab4c30 Astrophysics - Solar and Stellar Astrophysics; instabilities; parker solar probe; Physics - Geophysics; Physics - Plasma Physics; Physics - Space Physics; plasmas; Solar Probe Plus; Solar wind; Sun: corona; turbulence; waves |
| 2018 |
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Parametric instability, inverse cascade and the range of solar-wind turbulence In this paper, weak-turbulence theory is used to investigate the nonlinear evolution of the parametric instability in three-dimensional low-β plasmas at wavelengths much greater than the ion inertial length under the assumption that slow magnetosonic waves are strongly damped. It is shown analytically that the parametric instability leads to an inverse cascade of Alfv\ en wave quanta, and several exact solutions to the wave kinetic equations are presented. The main results of the paper concern the parametric decay of Alf ... YEAR: 2018 DOI: 10.1017/S0022377818000016 astrophysical plasmas; Astrophysics - Solar and Stellar Astrophysics; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; plasma nonlinear phenomena; plasma waves; Solar Probe Plus |
| 2016 |
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The FIELDS Instrument Suite for Solar Probe Plus NASA\textquoterights Solar Probe Plus (SPP) mission will make the first in situ measurements of the solar corona and the birthplace of the solar wind. The FIELDS instrument suite on SPP will make direct measurements of electric and magnetic fields, the properties of in situ plasma waves, electron density and temperature profiles, and interplanetary radio emissions, amongst other things. Here, we describe the scientific objectives targeted by the SPP/FIELDS instrument, the instrument design itself, and the instrument conce ... Bale, S.; Goetz, K.; Harvey, P.; Turin, P.; Bonnell, J.; de Wit, T.; Ergun, R.; MacDowall, R.; Pulupa, M.; Andre, M.; Bolton, M.; Bougeret, J.-L.; Bowen, T.; Burgess, D.; Cattell, C.; Chandran, B.; Chaston, C.; Chen, C.; Choi, M.; Connerney, J.; Cranmer, S.; Diaz-Aguado, M.; Donakowski, W.; Drake, J.; Farrell, W.; Fergeau, P.; Fermin, J.; Fischer, J.; Fox, N.; Glaser, D.; Goldstein, M.; Gordon, D.; Hanson, E.; Harris, S.; Hayes, L.; Hinze, J.; Hollweg, J.; Horbury, T.; Howard, R.; Hoxie, V.; Jannet, G.; Karlsson, M.; Kasper, J.; Kellogg, P.; Kien, M.; Klimchuk, J.; Krasnoselskikh, V.; Krucker, S.; Lynch, J.; Maksimovic, M.; Malaspina, D.; Marker, S.; Martin, P.; Martinez-Oliveros, J.; McCauley, J.; McComas, D.; McDonald, T.; Meyer-Vernet, N.; Moncuquet, M.; Monson, S.; Mozer, F.; Murphy, S.; Odom, J.; Oliverson, R.; Olson, J.; Parker, E.; Pankow, D.; Phan, T.; Quataert, E.; Quinn, T.; Ruplin, S.; Salem, C.; Seitz, D.; Sheppard, D.; Siy, A.; Stevens, K.; Summers, D.; Szabo, A.; Timofeeva, M.; Vaivads, A.; Velli, M.; Yehle, A.; Werthimer, D.; Wygant, J.; YEAR: 2016 DOI: 10.1007/s11214-016-0244-5 Coronal heating; Parker Data Used; parker solar probe; Solar Probe Plus |
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EVOLUTION OF THE PROTON VELOCITY DISTRIBUTION DUE TO STOCHASTIC HEATING IN THE NEAR-SUN SOLAR WIND We investigate how the proton distribution function evolves when the protons undergo stochastic heating by strong, low-frequency, Alfv\ en-wave turbulence under the assumption that β is small. We apply our analysis to protons undergoing stochastic heating in the supersonic fast solar wind and obtain proton distributions at heliocentric distances ranging from 4 to 30 solar radii. We find that the proton distribution develops non-Gaussian structure with a flat core and steep tail. For r\gt 5 RS, the proton distr ... Klein, Kristopher; Chandran, Benjamin; YEAR: 2016 DOI: 10.3847/0004-637X/820/1/47 Astrophysics - Solar and Stellar Astrophysics; parker solar probe; Physics - Plasma Physics; plasmas; Solar Probe Plus; Solar wind; turbulence; waves |
| 2015 |
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The Solar Wind Electrons Alphas and Protons (SWEAP) Investigation on Solar Probe Plus is a four sensor instrument suite that provides complete measurements of the electrons and ionized helium and hydrogen that constitute the bulk of solar wind and coronal plasma. SWEAP consists of the Solar Probe Cup (SPC) and the Solar Probe Analyzers (SPAN). SPC is a Faraday Cup that looks directly at the Sun and measures ion and electron fluxes and flow angles as a function of energy. SPAN consists of an ion and electron electrostatic ... Kasper, Justin; Abiad, Robert; Austin, Gerry; Balat-Pichelin, Marianne; Bale, Stuart; Belcher, John; Berg, Peter; Bergner, Henry; Berthomier, Matthieu; Bookbinder, Jay; Brodu, Etienne; Caldwell, David; Case, Anthony; Chandran, Benjamin; Cheimets, Peter; Cirtain, Jonathan; Cranmer, Steven; Curtis, David; Daigneau, Peter; Dalton, Greg; Dasgupta, Brahmananda; DeTomaso, David; Diaz-Aguado, Millan; Djordjevic, Blagoje; Donaskowski, Bill; Effinger, Michael; Florinski, Vladimir; Fox, Nichola; Freeman, Mark; Gallagher, Dennis; Gary, Peter; Gauron, Tom; Gates, Richard; Goldstein, Melvin; Golub, Leon; Gordon, Dorothy; Gurnee, Reid; Guth, Giora; Halekas, Jasper; Hatch, Ken; Heerikuisen, Jacob; Ho, George; Hu, Qiang; Johnson, Greg; Jordan, Steven; Korreck, Kelly; Larson, Davin; Lazarus, Alan; Li, Gang; Livi, Roberto; Ludlam, Michael; Maksimovic, Milan; McFadden, James; Marchant, William; Maruca, Bennet; McComas, David; Messina, Luciana; Mercer, Tony; Park, Sang; Peddie, Andrew; Pogorelov, Nikolai; Reinhart, Matthew; Richardson, John; Robinson, Miles; Rosen, Irene; Skoug, Ruth; Slagle, Amanda; Steinberg, John; Stevens, Michael; Szabo, Adam; Taylor, Ellen; Tiu, Chris; Turin, Paul; Velli, Marco; Webb, Gary; Whittlesey, Phyllis; Wright, Ken; Wu, S.; Zank, Gary; YEAR: 2015 DOI: 10.1007/s11214-015-0206-3 Acceleration; Corona; Heating; Parker Data Used; Solar Probe Plus; Solar wind plasma; SWEAP |
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A MODIFIED VERSION OF TAYLOR\textquoterightS HYPOTHESIS FOR SOLAR PROBE PLUS OBSERVATIONS The Solar Probe Plus (SPP) spacecraft will explore the near-Sun environment, reaching heliocentric distances less than 10 R☉ . Near Earth, spacecraft measurements of fluctuating velocities and magnetic fields taken in the time domain are translated into information about the spatial structure of the solar wind via Taylor\textquoterights \textquotedblleftfrozen turbulence\textquotedblright hypothesis. Near the perihelion of SPP, however, the solar-wind speed is comparable to the Alfv\ en speed, and Taylor\text ... Klein, Kristopher; Perez, Jean; Verscharen, Daniel; Mallet, Alfred; Chandran, Benjamin; YEAR: 2015 DOI: 10.1088/2041-8205/801/1/L18 Astrophysics - Solar and Stellar Astrophysics; Parker Data Used; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; plasmas; Solar Probe Plus; Solar wind; Sun: corona; turbulence |
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