On the Importance of Spatial and Velocity Resolution in the Hybrid-Vlasov Modeling of Collisionless Shocks

Pfau‐Kempf, Yann; Battarbee, Markus; Ganse, Urs; Hoilijoki, Sanni; Turc, Lucile; Alfthan, Sebastian von; Vainio, R.; Palmroth, Minna

doi:10.3389/fphy.2018.00044

Cited by 31 publications

(45 citation statements)

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“…Compressive waves in the foreshock can have even larger amplitudes closer to the shock (Hoppe et al, 1981). This may be due to the spatial resolution in our simulation, which can limit the steepening of the waves (Pfau-Kempf et al, 2018). This may also explain why the caviton shown in Fig.…”

Section: Comparison With Spacecraft Observationsmentioning

confidence: 93%

“…CC BY 4.0 License. possible consequences for the formation of magnetosheath structures such as jets (Hietala et al 2009, Palmroth et al 2018. Any such effects may be modulated by both SHFAs impinging on the shock and erosion such as seen associated with this magnetosheath cavity.…”

Section: Shock Erosionmentioning

confidence: 99%

“…Electrons are modelled as a charge-neutralizing fluid, and due to a realistic proton mass and charge, kinetic effects are simulated on physical instead of renormalized scales. As shown in Pfau- Kempf et al (2018), kinetic proton phenomena are successfully reproduced even when 15 the ion inertial ranges are not resolved, though spatial resolution does limit gradients, steepenings and thus possibly amplitudes of phenomena.…”

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confidence: 98%

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Cavitons and spontaneous hot flow anomalies in a hybrid-Vlasov global magnetospheric simulation

Blanco‐Cano¹,

Battarbee²,

Turc³

et al. 2018

Preprint

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Abstract. In this paper we present the first identification of foreshock cavitons and the formation of spontaneous hot flow anomalies (SHFAs) with the Vlasiator global magnetospheric hybrid-Vlasov simulation code. In agreement with previous studies we show that cavitons evolve into SHFAs. In the presented run, this occurs very near the bow shock. We report on SHFAs surviving the shock crossing into the downstream region, and show that the interaction of SHFAs with the bow shock can lead to the formation of a magnetosheath cavity, previously identified in observations and simulations. We report on 5 the first identification of long-term local weakening and erosion of the bow shock, associated with a region of increased foreshock SHFA and caviton formation, and repeated shock crossings by them. We show that SHFAs are linked to an increase in suprathermal particle pitch-angles spreads. The realistic length scales in our simulation allow us to present a statistical study of global caviton and SHFA size distributions, and their comparable size distributions support the theory that SHFAs are formed from cavitons. Virtual spacecraft observations are shown to be in good agreement with observational studies.

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Section: Comparison With Spacecraft Observationsmentioning

confidence: 93%

Section: Shock Erosionmentioning

confidence: 99%

mentioning

confidence: 98%

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Cavitons and spontaneous hot flow anomalies in a hybrid-Vlasov global magnetospheric simulation

Blanco‐Cano¹,

Battarbee²,

Turc³

et al. 2018

Preprint

Self Cite

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“…The most energetic ions may therefore not be properly described. In terms of the wave frequency range, the main limitation comes from the spatial and temporal resolution of the simulation, which limit the steepening of the waves and the development of high‐frequency oscillations such as the whistler wave packets commonly observed near the quasi‐parallel bow shock (Pfau‐Kempf et al, ). In the present study, we will therefore concentrate on waves at periods above 1 s, which are properly described in the current runs.…”

Section: Description Of the Modelmentioning

confidence: 99%

Foreshock Properties at Typical and Enhanced Interplanetary Magnetic Field Strengths: Results From Hybrid‐Vlasov Simulations

et al. 2018

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In this paper, we present a detailed study of the effects of the interplanetary magnetic field (IMF) strength on the foreshock properties at small and large scales. Two simulation runs performed with the hybrid‐Vlasov code Vlasiator with identical setup but with different IMF strengths, namely, 5 and 10 nT, are compared. We find that the bow shock position and shape are roughly identical in both runs, due to the quasi‐radial IMF orientation, in agreement with previous magnetohydrodynamic simulations and theory. Foreshock waves develop in a broader region in the higher IMF strength run, which we attribute to the larger growth rate of the waves. The velocity of field‐aligned beams remains essentially the same, but their density is generally lower when the IMF strength increases, due to the lower Mach number. Also, we identify in the regular IMF strength run ridges of suprathermal ions which disappear at higher IMF strength. These structures may be a new signature of the foreshock compressional boundary. The foreshock wave field is structured over smaller scales in higher IMF conditions, due to both the period of the foreshock waves and the transverse extent of the wave fronts being smaller. While the foreshock is mostly permeated by monochromatic waves at typical IMF strength, we find that magnetosonic waves at different frequencies coexist in the other run. They are generated by multiple beams of suprathermal ions, while only a single beam is observed at typical IMF strength. The consequences of these differences for solar wind‐magnetosphere coupling are discussed.

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“…over energy by rapidly stepping the analyser potential, simultaneously measuring over a range of angles in the plane containing the spin axis, while scanning over angles in the plane perpendicular to the spin axis with spacecraft rotation (Rosenbauer et al, 1977(Rosenbauer et al, , 1981. The spacecraft spin rate (60 s in this case) is the maximum solar wind VDF time resolution that can be achieved with such a setup, unless multiple instrument heads are installed (as has been done, for instance, for the Fast Plasma Investigation instruments on NASA's Magnetospheric MultiScale spacecraft; Pollock et al, 2016). A similar situation occurs on the Cluster satellites .…”

Section: Introductionmentioning

confidence: 99%

Manuscript revised in view of the reviewer comments

Keyser¹

2018

Preprint

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Space plasma spectrometers have often relied on spacecraft spin to collect three-dimensional particle velocity distributions, which simplifies the instrument design and reduces its resource budgets but limits the velocity distribution acquisition rate. This limitation can in part be overcome by the use of electrostatic deflectors at the entrance of the analyser. By mounting such a spectrometer on a Sun-pointing spacecraft, solar wind ion distributions can be acquired at a much higher rate because the solar wind ion population, which is a cold beam that fills only part of the sky around its mean arrival direction, always remains in view. The present paper demonstrates how the operation of such an instrument can be optimized through the use of beam tracking strategies. The underlying idea is that it is much more efficient to cover only that part of the energy spectrum and those arrival directions where the solar wind beam is expected to be. The advantages of beam tracking are a faster velocity distribution acquisition for a given angular and energy resolution, or higher angular and energy resolution for a given acquisition rate. It is demonstrated by simulation that such beam tracking strategies can be very effective while limiting the risk of losing the beam. They can be implemented fairly easily with present-day on-board processing resources.

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On the Importance of Spatial and Velocity Resolution in the Hybrid-Vlasov Modeling of Collisionless Shocks

Cited by 31 publications

References 50 publications

Cavitons and spontaneous hot flow anomalies in a hybrid-Vlasov global magnetospheric simulation

Cavitons and spontaneous hot flow anomalies in a hybrid-Vlasov global magnetospheric simulation

Foreshock Properties at Typical and Enhanced Interplanetary Magnetic Field Strengths: Results From Hybrid‐Vlasov Simulations

Manuscript revised in view of the reviewer comments

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