Deriving the bulk properties of solar wind electrons observed by Solar Orbiter

Nicolaou, Georgios; Wicks, Robert T.; Owen, C. J.; Kataria, D. O.; Chandrasekhar, Anekallu; Lewis, G. R.; Verscharen, Daniel; Fortunato, V.; Mele, G.; DeMarco, Rossana; Bruno, R.

doi:10.1051/0004-6361/202140875

Cited by 7 publications

(3 citation statements)

References 55 publications

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“…In addition, the spread of data in the T ⊥ /T ∥ -β ∥ parameter space is increased by pronounced small-scale intermittency in strong turbulence (Servidio et al 2014). The combination of in situ instruments on the Solar Orbiter spacecraft allows us to study particle distributions with a very high time resolution, which helps to gain fresh insight into the underlying processes (Adhikari et al 2021;D'Amicis et al 2021;Louarn et al 2021;Nicolaou et al 2021;Owen et al 2021). We expect high-cadence in situ observations in combination with kinetic simulations of the expanding solar wind (Dong et al 2014;Franci et al 2015;Hellinger et al 2015) to deliver further insights into this interplay in the future.…”

Section: Discussionmentioning

confidence: 99%

Conditions for Proton Temperature Anisotropy to Drive Instabilities in the Solar Wind

Opie

Verscharen

Chen

et al. 2022

ApJ

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Using high-resolution data from Solar Orbiter, we investigate the plasma conditions necessary for the proton temperature-anisotropy-driven mirror-mode and oblique firehose instabilities to occur in the solar wind. We find that the unstable plasma exhibits dependencies on the angle between the direction of the magnetic field and the bulk solar wind velocity which cannot be explained by the double-adiabatic expansion of the solar wind alone. The angle dependencies suggest that perpendicular heating in Alfvénic wind may be responsible. We quantify the occurrence rate of the two instabilities as a function of the length of unstable intervals as they are convected over the spacecraft. This analysis indicates that mirror-mode and oblique firehose instabilities require a spatial interval of length greater than 2–3 unstable wavelengths in order to relax the plasma into a marginally stable state and thus closer to thermodynamic equilibrium in the solar wind. Our analysis suggests that the conditions for these instabilities to act effectively vary locally on scales much shorter than the correlation length of solar wind turbulence.

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Section: Discussionmentioning

confidence: 99%

Conditions for Proton Temperature Anisotropy to Drive Instabilities in the Solar Wind

Opie

Verscharen

Chen

et al. 2022

ApJ

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“…We demonstrate the use of an appropriate forward model simulating the expected response of an electrostatic analyzer in the presence of plasma of heavy, negative ions. The development of forward models is not only useful in dataanalyses (e.g., Nicolaou et al, 2014b;Nicolaou et al, 2021;Wilson et al, 2008;Wilson et al, 2017, Elliott et al, 2016, but also in testing the performance of the instrument in a range of expected conditions (Kessel et al, 1989;Cara et al, 2017;Nicolaou et al, 2014c;Nicolaou et al, 2014b;Nicolaou et al, 2020a;Nicolaou et al, 2020b;Nicolaou and Livadiotis, 2016). In this study we focus on the ability to resolve key species for plasma science in the vicinity of Enceladus and Titan.…”

Section: Discussionmentioning

confidence: 99%

Resolving Space Plasma Species With Electrostatic Analyzers

Nicolaou

Haythornthwaite

Coates

2022

Front. Astron. Space Sci.

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Electrostatic analyzers resolve the energy-per-charge distributions of charged plasma particles. Some space plasma instruments use electrostatic analyzers among other units, such as aperture deflectors and position sensitive detectors, in order to resolve the three-dimensional energy (velocity) distribution functions of plasma particles. When these instruments do not comprise a mass analyzer unit, different species can be resolved only if there are measurable differences in their energy-per-charge distributions. This study examines the ability of single electrostatic analyzer systems in resolving co-moving plasma species with different mass-per-charge ratios. We consider examples of static plasma consisting of two species of heavy negative ions measured by a typical electrostatic analyzer design, similar to the electron spectrometer on board Cassini spacecraft. We demonstrate an appropriate modeling technique to simulate the basic features of the instrument response in the specific plasma conditions and we quantify its ability to resolve the key species as a function of the spacecraft speed and the plasma temperature. We show that for the parameter range we examine, the mass resolution increases with increasing spacecraft speed and decreasing plasma temperature. We also demonstrate how our model can analyze real measurements and drive future instrument designs.

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“…Throughout the shock event studied here, we find a discrepancy between the density estimated from the moments of the distribution function measured by the Proton and Alpha Sensor (PAS) of the SolO SWA suite and the density estimated from the spacecraft potential using RPW (Khotyaintsev et al 2021; see Figure 2). After analyzing the density computed as a moment of the electron distribution function (see Nicolaou et al 2021), we decided to use the density estimated via RPW for our analysis.…”

Section: Datamentioning

confidence: 99%

Properties of an Interplanetary Shock Observed at 0.07 and 0.7 au by Parker Solar Probe and Solar Orbiter

Trotta,

Larosa,

Nicolaou

et al. 2024

ApJ

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The Parker Solar Probe (PSP) and Solar Orbiter (SolO) missions opened a new observational window in the inner heliosphere, which is finally accessible to direct measurements. On 2022 September 5, a coronal mass ejection (CME)-driven interplanetary (IP) shock was observed as close as 0.07 au by PSP. The CME then reached SolO, which was radially well-aligned at 0.7 au, thus providing us with the opportunity to study the shock properties at different heliocentric distances. We characterize the shock, investigate its typical parameters, and compare its small-scale features at both locations. Using the PSP observations, we investigate how magnetic switchbacks and ion cyclotron waves are processed upon shock crossing. We find that switchbacks preserve their V–B correlation while compressed upon the shock passage, and that the signature of ion cyclotron waves disappears downstream of the shock. By contrast, the SolO observations reveal a very structured shock transition, with a population of shock-accelerated protons of up to about 2 MeV, showing irregularities in the shock downstream, which we correlate with solar wind structures propagating across the shock. At SolO, we also report the presence of low-energy (∼100 eV) electrons scattering due to upstream shocklets. This study elucidates how the local features of IP shocks and their environments can be very different as they propagate through the heliosphere.

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Deriving the bulk properties of solar wind electrons observed by Solar Orbiter

Abstract: Deriving the bulk properties of solar wind electrons observed by Solar Orbiter. A preliminary study of electron plasma thermodynamics. Astronomy & Astrophysics. pp. 1-13.

Cited by 7 publications

References 55 publications

Conditions for Proton Temperature Anisotropy to Drive Instabilities in the Solar Wind

Conditions for Proton Temperature Anisotropy to Drive Instabilities in the Solar Wind

Resolving Space Plasma Species With Electrostatic Analyzers

Properties of an Interplanetary Shock Observed at 0.07 and 0.7 au by Parker Solar Probe and Solar Orbiter

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