Measurement of Magnetic Field Fluctuations in the Parker Solar Probe and Solar Orbiter Missions

Jannet, G.; Wit, T. Dudok de; Krasnoselskikh, V.; Kretzschmar, M.; Fergeau, P.; Bergerard-Timofeeva, M.; Agrapart, C.; Brochot, J.-Y.; Chalumeau, Gilles; Martin, Philippe; Revillet, C.; Bale, S. D.; Maksimović, M.; Bowen, T. A.; Brysbaert, C.; Goetz, K.; Guilhem, E.; Leray, Vincent; Lorfèvre, E.

doi:10.1029/2020ja028543

Cited by 21 publications

(15 citation statements)

References 40 publications

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“…BPF data are available for only one component of the magnetic field. Here, we have the Bu component of the SCM (Jannet et al 2021). However, the main advantage compared to the three component cross-spectral data (∼28 s) is that BPF data are of a higher time resolution (∼0.87 s) and importantly both the peak and average data are available.…”

Section: Methods and Data For The Whistler Waves Analysismentioning

confidence: 99%

Whistler wave occurrence and the interaction with strahl electrons during the first encounter of Parker Solar Probe

Jagarlamudi

Wit

Froment

et al. 2021

A&A

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Aims. We studied the properties and occurrence of narrowband whistler waves and their interaction with strahl electrons observed between 0.17 and 0.26 au during the first encounter of Parker Solar Probe. Methods. We used Digital Fields Board band-pass filtered (BPF) data from FIELDS to detect the signatures of whistler waves. Additionally parameters derived from the particle distribution functions measured by the Solar Wind Electrons Alphas and Protons (SWEAP) instrument suite were used to investigate the plasma properties, and FIELDS suite measurements were used to investigate the electromagnetic (EM) fields properties corresponding to the observed whistler signatures. Results. We observe that the occurrence of whistler waves is low, nearly ~1.5% and less than 0.5% in the analyzed peak and average BPF data, respectively. Whistlers occur highly intermittently and 80% of the whistlers appear continuously for less than 3 s. The spacecraft frequencies of the analyzed waves are less than 0.2 electron cyclotron frequency (fce). The occurrence rate of whistler waves was found to be anticorrelated with the solar wind bulk velocity. The study of the duration of the whistler intervals revealed an anticorrelation between the duration and the solar wind velocity, as well as between the duration and the normalized amplitude of magnetic field variations. The pitch-angle widths (PAWs) of the field-aligned electron population referred to as the strahl are broader by at least 12 degrees during the presence of large amplitude narrowband whistler waves. This observation points toward an EM wave electron interaction, resulting in pitch-angle scattering. PAWs of strahl electrons corresponding to the short duration whistlers are higher compared to the long duration whistlers, indicating short duration whistlers scatter the strahl electrons better than the long duration ones. Parallel cuts through the strahl electron velocity distribution function (VDF) observed during the whistler intervals appear to depart from the Maxwellian shape typically found in the near-Sun strahl VDFs. The relative decrease in the parallel electron temperature and the increase in PAW for the electrons in the strahl energy range suggests that the interaction with whistler waves results in a transfer of electron momentum from the parallel to the perpendicular direction.

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Section: Methods and Data For The Whistler Waves Analysismentioning

confidence: 99%

Whistler wave occurrence and the interaction with strahl electrons during the first encounter of Parker Solar Probe

Jagarlamudi

Wit

Froment

et al. 2021

A&A

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“…Our analysis is based on measurements carried out between March 1, 2020 and December 3, 2020, using the magnetic and electric antennas (respectively SCM -Search Coil Magnetometer- (Jannet et al 2021) -and ANT) of the Radio and Plasma Waves (RPW, Maksimovic et al 2020) experiment on board Solar Orbiter. The data cover slightly more than the first orbit, at distances between 0.51 and 0.98 AU from the Sun.…”

Section: Data and Analysismentioning

confidence: 99%

Whistler waves observed by Solar Orbiter/RPW between 0.5 AU and 1 AU

Kretzschmar

Chust

Krasnoselskikh

et al. 2021

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Context. Solar wind evolution differs from a simple radial expansion, while wave-particle interactions are assumed to be the major cause for the observed dynamics of the electron distribution function. In particular, whistler waves are thought to inhibit the electron heat flux and ensure the diffusion of the field-aligned energetic electrons (Strahl electrons) to replenish the halo population. Aims. The goal of our study is to detect and characterize the electromagnetic waves that have the capacity to modify the electron distribution functions, with a special focus on whistler waves. Methods. We carried out a detailed analysis of the electric and magnetic field fluctuations observed by the Solar Orbiter spacecraft during its first orbit around the Sun, between 0.5 and 1 AU. Using data from the Search Coil Magnetometer and electric antenna, both part of the Radio and Plasma Waves (RPW) instrumental suite, we detected the electromagnetic waves with frequencies above 3 Hz and determined the statistical distribution of their amplitudes, frequencies, polarization, and k-vector as a function of distance. Here, we also discuss the relevant instrumental issues regarding the phase between the electric and magnetic measurements as well as the effective length of the electric antenna. Results. An overwhelming majority of the observed waves are right-handed circularly polarized in the solar wind frame and identified as outwardly propagating quasi-parallel whistler waves. Their occurrence rate increases by a least a factor of 2 from 1 AU to 0.5 AU. These results are consistent with the regulation of the heat flux by the whistler heat flux instability. Near 0.5 AU, whistler waves are found to be more field-aligned and to have a smaller normalized frequency (f/fce), larger amplitude, and greater bandwidth than at 1 AU.

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“…Electromagnetic fluctuations are measured by the RPW triaxal coplanar electric antenna system (ANT), its biasing unit (BIAS), and a triaxal search-coil magnetometer (SCM) (Jannet et al 2021). Their common, most exhaustive data product includes the recorded waveforms; however, due to their large size, full wave forms can only be downlinked for short periods of time.…”

Section: Electromagnetic Fluctuationsmentioning

confidence: 99%

Whistler instability driven by the sunward electron deficit in the solar wind

Berčič

Verscharen

Owen

et al. 2021

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Context. Solar wind electrons play an important role in the energy balance of the solar wind acceleration by carrying energy into interplanetary space in the form of electron heat flux. The heat flux is stored in the complex electron velocity distribution functions (VDFs) shaped by expansion, Coulomb collisions, and field-particle interactions. Aims. We investigate how the suprathermal electron deficit in the anti-strahl direction, which was recently discovered in the near-Sun solar wind, drives a kinetic instability and creates whistler waves with wave vectors that are quasi-parallel to the direction of the background magnetic field. Methods. We combine high-cadence measurements of electron pitch-angle distribution functions and electromagnetic waves provided by Solar Orbiter during its first orbit. Our case study is based on a burst-mode data interval from the Electrostatic Analyser System (SWA-EAS) at a distance of 112 R S (0.52 au) from the Sun, during which several whistler wave packets were detected by Solar Orbiter's Radio and Plasma Waves (RPW) instrument. Results. The sunward deficit creates kinetic conditions under which the quasi-parallel whistler wave is driven unstable. We directly test our predictions for the existence of these waves through solar wind observations. We find whistler waves that are quasi-parallel and almost circularly polarised, propagating away from the Sun, coinciding with a pronounced sunward deficit in the electron VDF. The cyclotron-resonance condition is fulfilled for electrons moving in the direction opposite to the direction of wave propagation, with energies corresponding to those associated with the sunward deficit. Conclusions. We conclude that the sunward deficit acts as a source of quasi-parallel whistler waves in the solar wind. The quasilinear diffusion of the resonant electrons tends to fill the deficit, leading to a reduction in the total electron heat flux.

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Measurement of Magnetic Field Fluctuations in the Parker Solar Probe and Solar Orbiter Missions

Cited by 21 publications

References 40 publications

Whistler wave occurrence and the interaction with strahl electrons during the first encounter of Parker Solar Probe

Whistler wave occurrence and the interaction with strahl electrons during the first encounter of Parker Solar Probe

Whistler waves observed by Solar Orbiter/RPW between 0.5 AU and 1 AU

Whistler instability driven by the sunward electron deficit in the solar wind

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