Found 29 entries in the Bibliography.
Showing entries from 1 through 29
| 2020 |
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The Electromagnetic Signature of Outward Propagating Ion-scale Waves First results from the Parker Solar Probe (PSP) mission have revealed ubiquitous coherent ion-scale waves in the inner heliosphere, which are signatures of kinetic wave-particle interactions and fluid instabilities. However, initial studies of the circularly polarized ion-scale waves observed by PSP have only thoroughly analyzed magnetic field signatures, precluding a determination of solar wind frame propagation direction and intrinsic wave polarization. A comprehensive determination of wave properties requires measureme ... Bowen, Trevor; Bale, Stuart; Bonnell, J.; Larson, Davin; Mallet, Alfred; McManus, Michael; Mozer, Forrest; Pulupa, Marc; Vasko, Ivan; Verniero, J.; YEAR: 2020 DOI: 10.3847/1538-4357/ab9f37 Astrophysics - Solar and Stellar Astrophysics; Parker Data Used; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; Plasma astrophysics; Plasma physics; Solar Probe Plus; Solar wind; Space plasmas |
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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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The nature of the plasma wave modes around the ion kinetic scales in highly Alfv\ enic slow solar wind turbulence is investigated using data from the NASA\textquoterights Parker Solar Probe taken in the inner heliosphere, at 0.18 au from the Sun. The joint distribution of the normalized reduced magnetic helicity σm (θRB, τ) is obtained, where θRB is the angle between the local mean magnetic field and the radial direction and τ is the temporal scale. Two populations around ion scales a ... . Y. Huang, S; Zhang, J.; Sahraoui, F.; He, J.; Yuan, Z.; es, Andr\; Hadid, L.; Deng, X.; Jiang, K.; Yu, L.; . Y. Xiong, Q; . Y. Wei, Y; Xu, S.; Bale, S.; Kasper, J.; YEAR: 2020 DOI: 10.3847/2041-8213/ab9abb 1261; 1534; 1544; 1693; 1873; 23; 711; 824; 830; Parker Data Used; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; Solar Probe Plus |
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Tearing Instability and Periodic Density Perturbations in the Slow Solar Wind In contrast with the fast solar wind, which originates in coronal holes, the source of the slow solar wind is still debated. Often intermittent and enriched with low first ionization potential elements\textemdashakin to what is observed in closed coronal loops\textemdashthe slow wind could form in bursty events nearby helmet streamers. Slow winds also exhibit density perturbations that have been shown to be periodic and could be associated with flux ropes ejected from the tip of helmet streamers, as shown recently by the ... eville, Victor; Velli, Marco; Rouillard, Alexis; Lavraud, Benoit; Tenerani, Anna; Shi, Chen; Strugarek, Antoine; YEAR: 2020 DOI: 10.3847/2041-8213/ab911d Astrophysics - Solar and Stellar Astrophysics; Magnetohydrodynamics; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; Plasma astrophysics; Slow solar wind; Solar magnetic reconnection; Solar Probe Plus; Solar wind |
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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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The Solar Probe Cup on the Parker Solar Probe Solar Probe Cup (SPC) is a Faraday cup instrument on board NASA\textquoterights Parker Solar Probe (PSP) spacecraft designed to make rapid measurements of thermal coronal and solar wind plasma. The spacecraft is in a heliocentric orbit that takes it closer to the Sun than any previous spacecraft, allowing measurements to be made where the coronal and solar wind plasma is being heated and accelerated. The SPC instrument was designed to be pointed directly at the Sun at all times, allowing the solar wind (which is flowing p ... Case, A.; Kasper, Justin; Stevens, Michael; Korreck, Kelly; Paulson, Kristoff; Daigneau, Peter; Caldwell, Dave; Freeman, Mark; Henry, Thayne; Klingensmith, Brianna; Bookbinder, J.; Robinson, Miles; Berg, Peter; Tiu, Chris; Wright, K.; Reinhart, Matthew; Curtis, David; Ludlam, Michael; Larson, Davin; Whittlesey, Phyllis; Livi, Roberto; Klein, Kristopher; c, Mihailo; YEAR: 2020 DOI: 10.3847/1538-4365/ab5a7b Astrophysics - Instrumentation and Methods for Astrophysics; Astrophysics - Solar and Stellar Astrophysics; Parker Data Used; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; Solar Probe Plus |
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Density Fluctuations in the Solar Wind Based on Type III Radio Bursts Observed by Parker Solar Probe Radio waves are strongly scattered in the solar wind, so that their apparent sources seem to be considerably larger and shifted than the actual ones. Since the scattering depends on the spectrum of density turbulence, a better understanding of the radio wave propagation provides indirect information on the relative density fluctuations, ϵ=⟨δn⟩/⟨n⟩\ ϵ=⟨δn⟩/⟨n⟩ , at the effective turbulence scale length. Here, we analyzed 30 type III bursts detected by Parker Sola ... Krupar, Vratislav; Szabo, Adam; Maksimovic, Milan; Kruparova, Oksana; Kontar, Eduard; Balmaceda, Laura; Bonnin, Xavier; Bale, Stuart; Pulupa, Marc; Malaspina, David; Bonnell, John; Harvey, Peter; Goetz, Keith; de Wit, Thierry; MacDowall, Robert; Kasper, Justin; Case, Anthony; Korreck, Kelly; Larson, Davin; Livi, Roberto; Stevens, Michael; Whittlesey, Phyllis; Hegedus, Alexander; YEAR: 2020 DOI: 10.3847/1538-4365/ab65bd Astrophysics - Earth and Planetary Astrophysics; Astrophysics - Solar and Stellar Astrophysics; Parker Data Used; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; Solar Probe Plus |
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Enhanced Energy Transfer Rate in Solar Wind Turbulence Observed near the Sun from Parker Solar Probe Direct evidence of an inertial-range turbulent energy cascade has been provided by spacecraft observations in heliospheric plasmas. In the solar wind, the average value of the derived heating rate near 1 au is \~10\ 3\ Jkg\ -1\ s\ -1\ \ \~103Jkg-1s-1 , an amount sufficient to account for observed departures from adiabatic expansion. Parker Solar Probe, even during its first solar encounter, offers the first opportunity to compute, in a similar fashion, a fluid-scale energy decay rate, mu ... Bandyopadhyay, Riddhi; Goldstein, M.; Maruca, B.; Matthaeus, W.; Parashar, T.; Ruffolo, D.; Chhiber, R.; Usmanov, A.; Chasapis, A.; Qudsi, R.; Bale, Stuart; Bonnell, J.; de Wit, Thierry; Goetz, Keith; Harvey, Peter; MacDowall, Robert; Malaspina, David; Pulupa, Marc; Kasper, J.; Korreck, K.; Case, A.; Stevens, M.; Whittlesey, P.; Larson, D.; Livi, R.; Klein, K.; Velli, M.; Raouafi, N.; YEAR: 2020 DOI: 10.3847/1538-4365/ab5dae Astrophysics - Solar and Stellar Astrophysics; Parker Data Used; parker solar probe; Physics - Plasma Physics; 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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Parker Solar Probe In Situ Observations of Magnetic Reconnection Exhausts during Encounter 1 Magnetic reconnection in current sheets converts magnetic energy into particle energy. The process may play an important role in the acceleration and heating of the solar wind close to the Sun. Observations from Parker Solar Probe (PSP) provide a new opportunity to study this problem, as it measures the solar wind at unprecedented close distances to the Sun. During the first orbit, PSP encountered a large number of current sheets in the solar wind through perihelion at 35.7 solar radii. We performed a comprehensive survey ... Phan, T.; Bale, S.; Eastwood, J.; Lavraud, B.; Drake, J.; Oieroset, M.; Shay, M.; Pulupa, M.; Stevens, M.; MacDowall, R.; Case, A.; Larson, D.; Kasper, J.; Whittlesey, P.; Szabo, A.; Korreck, K.; Bonnell, J.; de Wit, Dudok; Goetz, K.; Harvey, P.; Horbury, T.; Livi, R.; Malaspina, D.; Paulson, K.; Raouafi, N.; Velli, M.; YEAR: 2020 DOI: 10.3847/1538-4365/ab55ee Astrophysics - Solar and Stellar Astrophysics; Parker Data Used; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; Solar Probe Plus |
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Kinetic-scale Spectral Features of Cross Helicity and Residual Energy in the Inner Heliosphere In this work, we present the first results from the flux angle (FA) operation mode of the Faraday Cup instrument on board the Parker Solar Probe (PSP). The FA mode allows rapid measurements of phase space density fluctuations close to the peak of the proton velocity distribution function with a cadence of 293 Hz. This approach provides an invaluable tool for understanding kinetic-scale turbulence in the solar wind and solar corona. We describe a technique to convert the phase space density fluctuations into vector velocit ... Vech, Daniel; Kasper, Justin; Klein, Kristopher; Huang, Jia; Stevens, Michael; Chen, Christopher; Case, Anthony; Korreck, Kelly; Bale, Stuart; Bowen, Trevor; Whittlesey, Phyllis; Livi, Roberto; Larson, Davin; Malaspina, David; Pulupa, Marc; Bonnell, John; Harvey, Peter; Goetz, Keith; de Wit, Thierry; MacDowall, Robert; YEAR: 2020 DOI: 10.3847/1538-4365/ab60a2 Parker Data Used; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; Solar Probe Plus |
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Observations at 1 au have confirmed that enhancements in measured energetic-particle (EP) fluxes are statistically associated with "rough" magnetic fields, i.e., fields with atypically large spatial derivatives or increments, as measured by the Partial Variance of Increments (PVI) method. One way to interpret this observation is as an association of the EPs with trapping or channeling within magnetic flux tubes, possibly near their boundaries. However, it remains unclear whether this association is a transport or local ef ... Bandyopadhyay, Riddhi; Matthaeus, W.; Parashar, T.; Chhiber, R.; Ruffolo, D.; Goldstein, M.; Maruca, B.; Chasapis, A.; Qudsi, R.; McComas, D.; Christian, E.; Szalay, J.; Joyce, C.; Giacalone, J.; Schwadron, N.; Mitchell, D.; Hill, M.; Wiedenbeck, M.; McNutt, R.; Desai, M.; Bale, Stuart; Bonnell, J.; de Wit, Thierry; Goetz, Keith; Harvey, Peter; MacDowall, Robert; Malaspina, David; Pulupa, Marc; Velli, M.; Kasper, J.; Korreck, K.; Stevens, M.; Case, A.; Raouafi, N.; YEAR: 2020 DOI: 10.3847/1538-4365/ab6220 Astrophysics - Solar and Stellar Astrophysics; Parker Data Used; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; Solar Probe Plus |
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Observations of Heating along Intermittent Structures in the Inner Heliosphere from PSP Data The solar wind proton temperature at 1 au has been found to be correlated with small-scale intermittent magnetic structures, i.e., regions with enhanced temperature are associated with coherent structures, such as current sheets. Using Parker Solar Probe data from the first encounter, we study this association using measurements of the radial proton temperature, employing the partial variance of increments (PVI) technique to identify intermittent magnetic structures. We observe that the probability density functions of hi ... Qudsi, R.; Maruca, B.; Matthaeus, W.; Parashar, T.; Bandyopadhyay, Riddhi; Chhiber, R.; Chasapis, A.; Goldstein, Melvyn; Bale, S.; Bonnell, J.; de Wit, Dudok; Goetz, K.; Harvey, P.; MacDowall, R.; Malaspina, D.; Pulupa, M.; Kasper, J.; Korreck, K.; Case, A.; Stevens, M.; Whittlesey, P.; Larson, D.; Livi, R.; Velli, M.; Raouafi, N.; YEAR: 2020 DOI: 10.3847/1538-4365/ab5c19 Parker Data Used; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; Solar Probe Plus |
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Magnetic field fluctuations in the solar wind are commonly observed to follow a power-law spectrum. Near proton-kinetic scales, a spectral break occurs that is commonly interpreted as a transition to kinetic turbulence. However, this transition is not yet entirely understood. By studying the scaling of the break with various plasma properties, it may be possible to constrain the processes leading to the onset of kinetic turbulence. Using data from the Parker Solar Probe, we measure the proton-scale break over a range of h ... Duan, Die; Bowen, Trevor; Chen, Christopher; Mallet, Alfred; He, Jiansen; Bale, Stuart; Vech, Daniel; Kasper, J.; Pulupa, Marc; Bonnell, John; Case, Anthony; de Wit, Thierry; Goetz, Keith; Harvey, Peter; Korreck, Kelly; Larson, Davin; Livi, Roberto; MacDowall, Robert; Malaspina, David; Stevens, Michael; Whittlesey, Phyllis; YEAR: 2020 DOI: 10.3847/1538-4365/ab672d Parker Data Used; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; Solar Probe Plus |
| 2019 |
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Electron Energy Partition across Interplanetary Shocks. II. Statistics A statistical analysis of 15,210 electron velocity distribution function (VDF) fits, observed within \textpm2 hr of 52 interplanetary (IP) shocks by the Wind spacecraft near 1 au, is presented. This is the second in a three-part series on electron VDFs near IP shocks. The electron velocity moment statistics for the dense, low-energy core, tenuous, hot halo, and field-aligned beam/strahl are a statistically significant list of values illustrated with both histograms and tabular lists for reference and baselines in future w ... Wilson, Lynn; Chen, Li-Jen; Wang, Shan; Schwartz, Steven; Turner, Drew; Stevens, Michael; Kasper, Justin; Osmane, Adnane; Caprioli, Damiano; Bale, Stuart; Pulupa, Marc; Salem, Chadi; Goodrich, Katherine; YEAR: 2019 DOI: 10.3847/1538-4365/ab5445 Astrophysics - Solar and Stellar Astrophysics; Interplanetary particle acceleration; Interplanetary shocks; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; Plasma astrophysics; Plasma physics; Solar coronal mass ejection shocks; Solar coronal mass ejections; Solar Probe Plus; Solar wind; Space plasmas |
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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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On slow solar wind with high Alfv\ enicity: from composition and microphysics to spectral properties Alfv\ enic fluctuations are very common features in the solar wind and are found especially within the main portion of fast-wind streams while the slow wind usually is less Alfv\ enic and more variable. In general, the fast and slow winds show many differences, which span from the large-scale structure to small-scale phenomena, including also a different turbulent behaviour. Recent studies, however, have shown that even the slow wind can sometimes be highly Alfv\ enic, with fluctuations as large as those of the fast wind. ... textquoterightAmicis, Raffaella; Matteini, Lorenzo; Bruno, Roberto; YEAR: 2018 DOI: 10.1093/mnras/sty3329 Astrophysics - Solar and Stellar Astrophysics; methods: data analysis; parker solar probe; Physics - Data Analysis; Physics - Plasma Physics; Physics - Space Physics; Solar Probe Plus; Solar wind; Statistics and Probability; turbulence |
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Magnetic Helicity Reversal in the Corona at Small Plasma Beta Solar and stellar dynamos shed small-scale and large-scale magnetic helicity of opposite signs. However, solar wind observations and simulations have shown that some distance above the dynamo both the small-scale and large-scale magnetic helicities have reversed signs. With realistic simulations of the solar corona above an active region now being available, we have access to the magnetic field and current density along coronal loops. We show that a sign reversal in the horizontal averages of the magnetic helicity occurs ... Bourdin, Philippe; Singh, Nishant; Brandenburg, Axel; YEAR: 2018 DOI: 10.3847/1538-4357/aae97a Astrophysics - Solar and Stellar Astrophysics; dynamo; magnetohydrodynamics: MHD; methods: numerical; parker solar probe; Physics - Plasma Physics; Solar Probe Plus; Solar wind; Sun: corona; Sun: magnetic fields |
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Radial evolution of the solar wind in pure high-speed streams: HELIOS revised observations Spacecraft observations have shown that the proton temperature in the solar wind falls off with radial distance more slowly than expected for an adiabatic prediction. Usually, previous studies have been focused on the evolution of the solar-wind plasma by using the bulk speed as an order parameter to discriminate different regimes. In contrast, here, we study the radial evolution of pure and homogeneous fast streams (i.e. well-defined streams of coronal-hole plasma that maintain their identity during several solar rotatio ... Perrone, Denise; Stansby, D; Horbury, T; Matteini, L; YEAR: 2018 DOI: 10.1093/mnras/sty3348 parker solar probe; Physics - Plasma Physics; Physics - Space Physics; Solar Probe Plus; Solar wind; Sun: corona; Sun: heliosphere |
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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 |
| 2017 |
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A Zone of Preferential Ion Heating Extends Tens of Solar Radii from the Sun The extreme temperatures and nonthermal nature of the solar corona and solar wind arise from an unidentified physical mechanism that preferentially heats certain ion species relative to others. Spectroscopic indicators of unequal temperatures commence within a fraction of a solar radius above the surface of the Sun, but the outer reach of this mechanism has yet to be determined. Here we present an empirical procedure for combining interplanetary solar wind measurements and a modeled energy equation including Coulomb relax ... Kasper, J.; Klein, K.; Weber, T.; Maksimovic, M.; Zaslavsky, A.; Bale, S.; Maruca, B.; Stevens, M.; Case, A.; YEAR: 2017 DOI: 10.3847/1538-4357/aa84b1 acceleration of particles; Astrophysics - Solar and Stellar Astrophysics; magnetic fields; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; plasmas; Solar Probe Plus; Solar wind; Sun: corona; turbulence |
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Langmuir wave electric fields induced by electron beams in the heliosphere Solar electron beams responsible for type III radio emission generate Langmuir waves as they propagate out from the Sun. The Langmuir waves are observed via in situ electric field measurements. These Langmuir waves are not smoothly distributed but occur in discrete clumps, commonly attributed to the turbulent nature of the solar wind electron density. Exactly how the density turbulence modulates the Langmuir wave electric fields is understood only qualitatively. Using weak turbulence simulations, we investigate how solar ... YEAR: 2017 DOI: 10.1051/0004-6361/201629697 Astrophysics - Solar and Stellar Astrophysics; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; Solar Probe Plus; Solar wind; Sun: flares; Sun: heliosphere; Sun: magnetic fields; Sun: particle emission; Sun: radio radiation |
| 2016 |
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MEASURING COLLISIONLESS DAMPING IN HELIOSPHERIC PLASMAS USING FIELD\textendashPARTICLE CORRELATIONS An innovative field-particle correlation technique is proposed that uses single-point measurements of the electromagnetic fields and particle velocity distribution functions to investigate the net transfer of energy from fields to particles associated with the collisionless damping of turbulent fluctuations in weakly collisional plasmas, such as the solar wind. In addition to providing a direct estimate of the local rate of energy transfer between fields and particles, it provides vital new information about the distribut ... YEAR: 2016 DOI: 10.3847/2041-8205/826/2/L30 Astrophysics - Solar and Stellar Astrophysics; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; plasmas; Solar Probe Plus; Solar wind; turbulence; waves |
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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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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 |
| 2014 |
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DYNAMICS OF DOUBLE LAYERS, ION ACCELERATION, AND HEAT FLUX SUPPRESSION DURING SOLAR FLARES Observations of flare-heated electrons in the corona typically suggest confinement of electrons. The confinement mechanism, however, remains unclear. The transport of coronal hot electrons into ambient plasma was recently investigated by particle-in-cell (PIC) simulations. Electron transport was significantly suppressed by the formation of a highly localized, nonlinear electrostatic potential in the form of a double layer (DL). In this work large-scale PIC simulations are performed to explore the dynamics of DLs in larger ... Li, T.; Drake, J.; Swisdak, M.; YEAR: 2014 DOI: 10.1088/0004-637X/793/1/7 acceleration of particles; Astrophysics - Solar and Stellar Astrophysics; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; Solar Probe Plus; Solar wind; Sun: corona; Sun: flares |
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THE VIOLATION OF THE TAYLOR HYPOTHESIS IN MEASUREMENTS OF SOLAR WIND TURBULENCE Motivated by the upcoming Solar Orbiter and Solar Probe Plus missions, qualitative and quantitative predictions are made for the effects of the violation of the Taylor hypothesis on the magnetic energy frequency spectrum measured in the near-Sun environment. The synthetic spacecraft data method is used to predict observational signatures of the violation for critically balanced Alfv\ enic turbulence or parallel fast/whistler turbulence. The violation of the Taylor hypothesis can occur in the slow flow regime, leading to a ... Klein, K.; Howes, G.; TenBarge, J.; YEAR: 2014 DOI: 10.1088/2041-8205/790/2/L20 Astrophysics - Solar and Stellar Astrophysics; parker solar probe; Physics - Plasma Physics; Physics - Space Physics; plasmas; Solar Probe Plus; Solar wind; turbulence; waves |
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VALIDITY OF THE TAYLOR HYPOTHESIS FOR LINEAR KINETIC WAVES IN THE WEAKLY COLLISIONAL SOLAR WIND The interpretation of single-point spacecraft measurements of solar wind turbulence is complicated by the fact that the measurements are made in a frame of reference in relative motion with respect to the turbulent plasma. The Taylor hypothesis\textemdashthat temporal fluctuations measured by a stationary probe in a rapidly flowing fluid are dominated by the advection of spatial structures in the fluid rest frame\textemdashis often assumed to simplify the analysis. But measurements of turbulence in upcoming missions, such ... Howes, G.; Klein, K.; TenBarge, J.; YEAR: 2014 DOI: 10.1088/0004-637X/789/2/106 Astrophysics - Solar and Stellar Astrophysics; parker solar probe; Physics - Plasma Physics; Solar Probe Plus; Solar wind; turbulence |
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