On the Effects of Pickup Ion-driven Waves on the Diffusion Tensor of Low-energy Electrons in the Heliosphere

Engelbrecht, N. Eugene

doi:10.3847/2041-8213/aa9372

“…This was usually done by comparing computed with measured electron intensities at Earth during periods of good or bad magnetic connection. Furthermore, given the demonstrated sensitivity of computed low-energy galactic electron intensities to various turbulence quantities (see Engelbrecht & Burger 2010Engelbrecht 2019), it may be possible to draw conclusions from Jovian electrons to better understand the behaviour of those quantities in regions of the heliosphere where spacecraft observations of this character do not exist (see, e.g., Engelbrecht 2017). Since these transport parameters and the diffusion coefficients they depend on are spatially dependent, the time that particles reside in a certain part of the heliosphere may yield significant insights to the modulation of GCRs as well.…”

Section: Jovian Electrons As Test Particlesmentioning

confidence: 99%

The residence-time of Jovian electrons in the inner heliosphere

Vogt

¹

,

Engelbrecht

²

,

Strauss

³

et al. 2020

A&A

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Context. Jovian electrons serve an important role in test-particle distribution in the inner heliosphere. They have been used extensively in the past to study the (diffusive) transport of cosmic rays in the inner heliosphere. With new limits on the Jovian source function, that is, the particle intensity just outside the Jovian magnetosphere, and a new set of in-situ observations at 1 AU for cases of both good and poor magnetic connection between the source and observer, we revisit some of these earlier simulations. Aims. We aim to find the optimal numerical set-up that can be used to simulate the propagation of 6 MeV Jovian electrons in the inner heliosphere. Using such a setup, we further aim to study the residence (propagation) times of these particles for different levels of magnetic connection between Jupiter and an observer at Earth (1 AU). Methods. Using an advanced Jovian electron propagation model based on the stochastic differential equation approach, we calculated the Jovian electron intensity for different model parameters. A comparison with observations leads to an optimal numerical setup, which was then used to calculate the so-called residence (propagation) times of these particles. Results. Through a comparison with in-situ observations, we were able to derive transport parameters that are appropriate for the study of the propagation of 6 MeV Jovian electrons in the inner heliosphere. Moreover, using these values, we show that the method of calculating the residence time applied in the existing literature is not suited to being interpreted as the propagation time of physical particles. This is due to an incorrect weighting of the probability distribution. We applied a new method, where the results from each pseudo-particle are weighted by its resulting phase-space density (i.e. the number of physical particles that it represents). We thereby obtained more reliable estimates for the propagation time.

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“…For instance, knowledge of spatial distribution of turbulence intensity is an important input for computations of energetic particle propagation throughout the heliosphere. Coupling global heliospheric models and turbulence transport models provides not only mean-flow plasma and magnetic field parameters, but also the turbulence quantities, which makes them useful also for calculation of diffusion coefficients and modulation of galactic cosmic rays (GCRs) (see, e.g., Florinski et al 2013a;Engelbrecht and Burger 2013;Wiengarten et al 2016;Chhiber et al 2017;Engelbrecht 2017;Zhao et al 2018). This topic is reviewed by Engelbrecht et al (2022) in this journal.…”

Section: Modeling Of the Supersonic Solar Wind With Turbulence Transportmentioning

confidence: 99%

Turbulence in the Outer Heliosphere

Fraternale

¹

,

Adhikari

²

,

Fichtner

³

et al. 2022

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The solar wind (SW) and local interstellar medium (LISM) are turbulent media. Their interaction is governed by complex physical processes and creates heliospheric regions with significantly different properties in terms of particle populations, bulk flow and turbulence. Our knowledge of the solar wind turbulence nature and dynamics mostly relies on near-Earth and near-Sun observations, and has been increasingly improving in recent years due to the availability of a wealth of space missions, including multi-spacecraft missions. In contrast, the properties of turbulence in the outer heliosphere are still not completely understood. In situ observations by Voyager and New Horizons, and remote neutral atom measurements by IBEX strongly suggest that turbulence is one of the critical processes acting at the heliospheric interface. It is intimately connected to charge exchange processes responsible for the production of suprathermal ions and energetic neutral atoms. This paper reviews the observational evidence of turbulence in the distant SW and in the LISM, advances in modeling efforts, and open challenges.

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“…For instance, knowledge of spatial distribution of turbulence intensity is an important input for computations of energetic particle propagation throughout the heliosphere. Coupling global heliospheric models and turbulence transport models provides not only mean-flow plasma and magnetic field parameters, but also the turbulence quantities, which makes them useful also for calculation of diffusion coefficients and modulation of galactic cosmic rays (GCRs) (see, e.g., Florinski et al, 2013a;Engelbrecht and Burger, 2013;Wiengarten et al, 2016;Chhiber et al, 2017;Engelbrecht, 2017;Zhao et al, 2018). This topic is reviewed by Engelbrecht et al (2022) in this volume.…”

Section: Evidence Of Turbulence In the Distant Supersonic Solar Windmentioning

confidence: 99%

Turbulence in the outer heliosphere

Fraternale¹,

Adhikari²,

Fichtner³

et al. 2022

Preprint

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The solar wind (SW) and local interstellar medium (LISM) are turbulent media. Their interaction is governed by complex physical processes and creates heliospheric regions with significantly different properties in terms of particle populations, bulk flow and turbulence. Our knowledge of the solar wind turbulence nature and dynamics mostly relies on near-Earth and near-Sun observations, and has been increasingly improving in recent years due to the availability of a wealth of space missions, including multi-spacecraft missions. In contrast, the properties of turbulence in the outer heliosphere are still not completely understood. In situ observations by Voyager and New Horizons, and remote neutral atom measurements by IBEX strongly suggest that turbulence is one of the critical processes acting at the heliospheric interface. It is intimately connected to charge exchange processes responsible for the production of suprathermal ions and energetic neutral atoms. This paper reviews the observational evidence of turbulence in the distant SW and in the LISM, advances in modeling efforts, and open challenges.Keywords Turbulence • Solar wind • Interstellar medium • Heliosphere 1 Some definitions and nomenclature that will be used throughout in this paper are given: the Elsässer energies (Z ± ) 2 = z ± 2 /2, total turbulence energy density,Alfvén ratio r A = Eu/E b . Eu = δu 2 /2 and E b = δB 2 /(µ 0 ρ)/2 are the turbulent kinetic energy and magnetic energy densities in Alfvén units, respectively.

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On the Effects of Pickup Ion-driven Waves on the Diffusion Tensor of Low-energy Electrons in the Heliosphere

Cited by 18 publications

References 51 publications

The residence-time of Jovian electrons in the inner heliosphere

The residence-time of Jovian electrons in the inner heliosphere

Turbulence in the Outer Heliosphere

Turbulence in the outer heliosphere

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