Reconstruction of Polarization Properties of Whistler Waves From Two Magnetic and Two Electric Field Components: Application to Parker Solar Probe Measurements

Colomban, L.; Agapitov, O. V.; Krasnoselskikh, V.; Kretzschmar, M.; Dudok de Wit, T.; Karbashewski, S.; Mozer, F. S.; Bonnell, J. W.; Bale, S.; Malaspina, D.; Raouafi, N. E.

doi:10.1029/2023ja031427

Cited by 3 publications

(2 citation statements)

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“…Accounting for Doppler shift, whistlers observed within magnetic dips typically have relative frequencies ω/Ω e in the plasma frame between 0.05 and 0.2 (Agapitov et al 2020;Karbashewski et al 2023;Colomban et al 2023Colomban et al , 2024. Ω e = 2πf ce = eB 0 /m e is the unsigned angular cyclotron frequency.…”

Section: Localized Bursts Of Sunward Propagating Whistlersmentioning

confidence: 99%

“…Second, there are strong whistler activities below 50R S (Agapitov et al 2020;Cattell et al 2020Cattell et al , 2021a, which sharply drop out below 25R S (Cattell et al 2022;Froment et al 2023). In Encounter 1, these whistlers are often collocated with magnetic dips at switchback boundaries, especially at the edges of the dips where there is a large magnetic gradient (Agapitov et al 2020;Froment et al 2023;Karbashewski et al 2023;Colomban et al 2023).…”

Section: Introductionmentioning

confidence: 99%

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Enhanced Efficiency of Solar Wind Electron Interaction with Whistlers Caused by Switchback-related Magnetic Dips

Vo,

Agapitov,

Choi

et al. 2024

ApJL

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Through test particle simulations based on solar wind observations by the Parker Solar Probe (PSP) mission, we demonstrate that a magnetic gradient can significantly enhance the efficiency of scattering and energization of the strahl electrons by quasi-parallel whistlers, through the phase trapping effect due to the gyrosurfing mechanism. We identify quasi-linear and nonlinear regimes of these interactions for different combinations of wave amplitude (B w /B 0) and the strength of the magnetic field gradient with magnetic field depletion level (B h /B 0) as a proxy. Nonlinear effects are observed for B w /B 0 ≳ 10−3 and B h /B 0 ≳ 0.1. We estimated the extending of the resonant energy range due to the wave and the magnetic field gradient interplay and demonstrated that these mechanisms result in the broadening of the strahl electron pitch-angle distribution typically observed in situ. The combination of parallel whistlers collocated with a magnetic gradient is frequently observed by PSP in magnetic dips at the edges of magnetic switchbacks. Our results indicate that these mechanisms may be highly relevant for pitch-angle scattering of the strahl electrons and regulating the heat flux near the Sun at heliocentric distances of 30–45 R S . Specifically, core and halo electrons may experience a 10% increase in their initial energy, and the majority of strahl electrons may be scattered (by an average of 30°) into the hot and trapped plasma inside magnetic dips.

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Section: Localized Bursts Of Sunward Propagating Whistlersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Enhanced Efficiency of Solar Wind Electron Interaction with Whistlers Caused by Switchback-related Magnetic Dips

Vo,

Agapitov,

Choi

et al. 2024

ApJL

Self Cite

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Quantifying the diffusion of suprathermal electrons by whistler waves between 0.2 and 1 AU with Solar Orbiter and Parker Solar Probe

Colomban,

Kretzschmar,

Krasnoselkikh

et al. 2024

A&A

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The evolution of the solar wind electron distribution function with heliocentric distance exhibits different features that are still unexplained, in particular, the fast decrease in the electron heat flux and the increase in the Strahl pitch angle width. Wave-particle interactions between electrons and whistler waves are often proposed to explain these phenomena. We aim to quantify the effect of whistler waves on suprathermal electrons as a function of heliocentric distance. We first performed a statistical analysis of whistler waves (occurrence and properties) observed by Solar Orbiter and Parker Solar Probe between 0.2 and 1 AU. The wave characteristics were then used to compute the diffusion coefficients for solar wind suprathermal electrons in the framework of quasi-linear theory. These coefficients were integrated to deduce the overall effect of whistler waves on electrons along their propagation. About $110,000$ whistler wave packets were detected and characterized in the plasma frame, including their direction of propagation with respect to the background magnetic field and their radial direction of propagation. Most waves are aligned with the magnetic field and only $ 0.5 <!PCT!>$ of them have a propagation angle greater than $45^ Beyond 0.3 AU, it is almost exclusively quasi-parallel waves propagating anti-sunward (some of them are found sunward but are within switchbacks with a change of sign of the radial component of the background magnetic) that are observed. Thus, these waves are found to be Strahl-aligned and not counter-streaming. At 0.2 AU, we find both Strahl-aligned and counter-streaming quasi-parallel whistler waves. Beyond 0.3 AU, the integrated diffusion coefficients show that the observed waves are sufficient to explain the measured Strahl pitch angle evolution and effective in isotropizing the halo. Strahl diffusion is mainly attributed to whistler waves with a propagation angle of $ although their origin has not yet been fully determined. Near 0.2 AU, counter-streaming whistler waves are able to diffuse the Strahl electrons more efficiently than the Strahl-aligned waves by two orders of magnitude.

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Whistler Waves in the Young Solar Wind: Statistics of Amplitude and Propagation Direction from Parker Solar Probe Encounters 1–11

Choi,

Agapitov,

Colomban

et al. 2024

ApJ

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In the interplanetary space solar wind plasma, whistler waves are observed in a wide range of heliocentric distances (from ∼20 solar radii (RS) to Jupiter’s orbit). They are known to interact with solar wind suprathermal electrons (strahl and halo) and to regulate the solar wind heat flux through scattering the strahl electrons. We present the results of applying the technique to determine the whistler wave propagation directions to the spectral data continuously collected by the FIELDS instruments on board Parker Solar Probe (PSP). The technique was validated based on the results obtained from burst mode magnetic and electric field waveform data collected during Encounter 1. We estimated the effective length of the PSP electric field antennas for a variety of solar wind conditions in the whistler wave frequency range and utilized these estimates for determining the whistler wave properties during PSP Encounters 1–11. Our findings show that (1) the enhancement of the whistler wave occurrence rate and wave amplitudes observed between 25 and 35 RS is predominantly due to the sunward-propagating whistler wave population associated with the switchback-related magnetic dips; (2) the antisunward or counterpropagating cases are observed at 30–40 RS; (3) between 40 and 50 RS, sunward and antisunward whistlers are observed with comparable occurrence rates; and (4) almost no sunward or counterpropagating whistlers were observed at heliocentric distances above 50 RS.

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Reconstruction of Polarization Properties of Whistler Waves From Two Magnetic and Two Electric Field Components: Application to Parker Solar Probe Measurements

Cited by 3 publications

References 76 publications

Enhanced Efficiency of Solar Wind Electron Interaction with Whistlers Caused by Switchback-related Magnetic Dips

Enhanced Efficiency of Solar Wind Electron Interaction with Whistlers Caused by Switchback-related Magnetic Dips

Quantifying the diffusion of suprathermal electrons by whistler waves between 0.2 and 1 AU with Solar Orbiter and Parker Solar Probe

Whistler Waves in the Young Solar Wind: Statistics of Amplitude and Propagation Direction from Parker Solar Probe Encounters 1–11

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