Particle‐in‐cell simulations of the lunar wake with high phase space resolution

Birch, Paul C.; Chapman, Sandra C.

doi:10.1029/2000gl011958

Cited by 37 publications

(42 citation statements)

References 9 publications

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“…Downstream from the Moon, further than 3 lunar radii ( R L ), observations and simulations indicate low density accelerated ion beams refilling the wake along the interplanetary magnetic field lines (IMF) through plasma thermal expansion and the resulting ambipolar electric field [ Ogilvie et al , 1996; Farrell et al , 1998; Birch and Chapman , 2001]. Low‐density and high‐energy protons downstream in the lunar wake can be explained through one‐dimensional (1‐D) plasma expansion theory [ Allen and Andrews , 1970; Denavit , 1979].…”

Section: Introductionmentioning

confidence: 99%

The effects of lunar surface plasma absorption and solar wind temperature anisotropies on the solar wind proton velocity space distributions in the low‐altitude lunar plasma wake

Fatemi¹,

Holmström²,

Futaana³

2012

J. Geophys. Res.

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[1] We study the solar wind proton velocity space distribution functions on the lunar nightside at low altitudes ($100 km) above the lunar surface using a three-dimensional hybrid plasma solver, when the Moon is in the unperturbed solar wind. When the solar wind encounters a passive obstacle, such as the Moon, without any strong magnetic field and no atmosphere, solar wind protons that impact the obstacle's surface are absorbed and removed from the velocity space distribution functions. We show first that a hybrid model of plasma is applicable to study the low-altitude lunar plasma wake by comparing the simulation results with observations. Then we examine the effects of a solar wind bi-Maxwellian velocity space distribution function and the lunar surface plasma absorption on the solar wind protons' velocity space distribution functions and their entry in the direction parallel to the interplanetary magnetic field lines into the low-altitude lunar wake. We present a backward Liouville method for particle-in-cell solvers that improves velocity space resolution. The results show that the lunar surface plasma absorption and anisotropic solar wind velocity space distributions result in substantial changes in the solar wind proton distribution functions in the low-altitude lunar plasma wake, modifying proton number density, velocity, and temperature there. Additionally, a large temperature anisotropy is found at close distances to the Moon on the lunar nightside as a consequence of the lunar surface plasma absorption effect.Citation: Fatemi, S., M. Holmström, and Y. Futaana (2012), The effects of lunar surface plasma absorption and solar wind temperature anisotropies on the solar wind proton velocity space distributions in the low-altitude lunar plasma wake, J. Geophys.

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Section: Introductionmentioning

confidence: 99%

The effects of lunar surface plasma absorption and solar wind temperature anisotropies on the solar wind proton velocity space distributions in the low‐altitude lunar plasma wake

Fatemi¹,

Holmström²,

Futaana³

2012

J. Geophys. Res.

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“…As in Birch and Chapman [13], ∼ 2500 particles per cell were used, compared with ∼ 80 particles per cell used by Farrell et al [12]. Figure 1 shows the geometry of the simulation.…”

Section: The Particle-in-cell Simulationmentioning

confidence: 99%

“…Simulations of this nature have previously been undertaken [12,13,14]. Intriguingly, whereas Farrell et al [12] find that the ion dynamics dominate the interaction, the higher phase space resolutions of Birch and Chapman [13,14] established that the electron dynamics dominate the evolution of the wake.…”

Section: Introductionmentioning

confidence: 99%

“…Intriguingly, whereas Farrell et al [12] find that the ion dynamics dominate the interaction, the higher phase space resolutions of Birch and Chapman [13,14] established that the electron dynamics dominate the evolution of the wake. In this paper we present new results from these simulations, including detailed particle density and electric field descriptions, a comprehensive analysis of the electron instabilities occurring in the wake, and a detailed description of the structure and dynamics of electron phase space holes generated in the wake that are not found in previous simulations.…”

Section: Introductionmentioning

confidence: 99%

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Detailed structure and dynamics in particle-in-cell simulations of the lunar wake

Birch

Chapman

2001

Physics of Plasmas

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The solar wind plasma from the Sun interacts with the Moon, generating a wake structure behind it, since the Moon is to a good approximation an insulator, has no intrinsic magnetic field and a very thin atmosphere. The lunar wake in simplified geometry has been simulated via a 1 1 2 D electromagnetic particle-in-cell code, with high resolution in order to resolve the full phase space dynamics of both electrons and ions. The simulation begins immediately downstream of the moon, before the solar wind has infilled the wake region, then evolves in the solar wind rest frame. An ambipolar electric field and a potential well are generated by the electrons, which subsequently create a counter-streaming beam distribution, causing a two-stream instability which confines the electrons. This also creates a number of electron phase space holes. Ion beams are accelerated into the wake by the ambipolar electric field, generating a two stream distribution with phase space mixing that is strongly influenced by the potentials created by the electron twostream instability. The simulations compare favourably with WIND observations.

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“…In the previous full PIC simulations (Birch and Chapman, 2001;Pecseli, 2004, 2005;Kimura and Nakagawa, 2008) particle entry into the plasma void due to thermal diffusion was considered, but the effect of the ion cyclotron motion was not included. Since the thermal cyclotron radius of ions is large, ion cyclotron motion may play an essential role for the entry of ions into the wake (e.g., Nishino et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Effect of ion cyclotron motion on the structure of wakes: A Vlasov simulation

Umeda

2012

Earth Planet Sp

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The global structure of wake fields behind an unmagnetized object in the solar wind is studied by means of a 2.5-dimensional full electromagnetic Vlasov simulation. The interaction of a plasma flow with an unmagnetized object is quite different from that with a magnetized object such as the Earth. Due to the absence of the global magnetic field, the unmagnetized object absorbs plasma particles which reach the surface, generating a plasma cavity called a wake on the anti-solar side of the object. The interaction between the solar wind with an out-ofplane interplanetary magnetic field and an unmagnetized object of ion-gyro scale is examined to study the effect of the ion cyclotron motion on the structure of wake fields. It is shown that the wake boundary layer is broadened when the inner product of the electric force and the density gradient of the wake boundary layer is negative. On the other hand, a steep wake boundary layer is formed with a negative inner product. The result suggests that the structures of wake fields become asymmetric due to the in-plane E cross B drift motion of ions.

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Particle‐in‐cell simulations of the lunar wake with high phase space resolution

Cited by 37 publications

References 9 publications

The effects of lunar surface plasma absorption and solar wind temperature anisotropies on the solar wind proton velocity space distributions in the low‐altitude lunar plasma wake

The effects of lunar surface plasma absorption and solar wind temperature anisotropies on the solar wind proton velocity space distributions in the low‐altitude lunar plasma wake

Detailed structure and dynamics in particle-in-cell simulations of the lunar wake

Effect of ion cyclotron motion on the structure of wakes: A Vlasov simulation

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