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Title: Kinetic electron and ion instability of the lunar wake simulated at physical mass ratio

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 22; Journal Issue: 3; Related Information: CHORUS Timestamp: 2016-12-26 04:23:15; Journal ID: ISSN 1070-664X
American Institute of Physics
Country of Publication:
United States

Citation Formats

Haakonsen, Christian Bernt, Hutchinson, Ian H., and Zhou, Chuteng. Kinetic electron and ion instability of the lunar wake simulated at physical mass ratio. United States: N. p., 2015. Web. doi:10.1063/1.4915525.
Haakonsen, Christian Bernt, Hutchinson, Ian H., & Zhou, Chuteng. Kinetic electron and ion instability of the lunar wake simulated at physical mass ratio. United States. doi:10.1063/1.4915525.
Haakonsen, Christian Bernt, Hutchinson, Ian H., and Zhou, Chuteng. 2015. "Kinetic electron and ion instability of the lunar wake simulated at physical mass ratio". United States. doi:10.1063/1.4915525.
title = {Kinetic electron and ion instability of the lunar wake simulated at physical mass ratio},
author = {Haakonsen, Christian Bernt and Hutchinson, Ian H. and Zhou, Chuteng},
abstractNote = {},
doi = {10.1063/1.4915525},
journal = {Physics of Plasmas},
number = 3,
volume = 22,
place = {United States},
year = 2015,
month = 3

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1063/1.4915525

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Cited by: 5works
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  • The solar wind wake behind the moon is studied with 1D electrostatic particle-in-cell (PIC) simulations using a physical ion to electron mass ratio (unlike prior investigations); the simulations also apply more generally to supersonic flow of dense magnetized plasma past non-magnetic objects. A hybrid electrostatic Boltzmann electron treatment is first used to investigate the ion stability in the absence of kinetic electron effects, showing that the ions are two-stream unstable for downstream wake distances (in lunar radii) greater than about three times the solar wind Mach number. Simulations with PIC electrons are then used to show that kinetic electron effectsmore » can lead to disruption of the ion beams at least three times closer to the moon than in the hybrid simulations. This disruption occurs as the result of a novel wake phenomenon: the non-linear growth of electron holes spawned from a narrow dimple in the electron velocity distribution. Most of the holes arising from the dimple are small and quickly leave the wake, approximately following the unperturbed electron phase-space trajectories, but some holes originating near the center of the wake remain and grow large enough to trigger disruption of the ion beams. Non-linear kinetic-electron effects are therefore essential to a comprehensive understanding of the 1D electrostatic stability of such wakes, and possible observational signatures in ARTEMIS data from the lunar wake are discussed.« less
  • In particle-in-cell (PIC) simulation studies of ion-ion two-stream instability, a reduced ion-to-electron mass ratio is often employed to save computation time. It is tacitly assumed that electrons do not play a significant role in the evolution of the instability as the ion-ion interactions are regarded to occur on time scales much slower than the response time of electrons. However, as the effect of such a reduced mass ratio has never been closely examined, we have studied the evolution of the ion beam driven instability using a one-dimensional electrostatic PIC code by rescaling the simulation parameters according to the ion-electron massmore » ratio. We made a reference simulation run with a mass ratio of 100 first and compared the results to the simulation results using the real mass ratio with parameters rescaled from those of the reduced mass ratio. External electric fields were applied in these simulations, which accelerated the electrons and excited an ion acoustic type instability, forming electron phase space holes. Merging of the electron holes affected the ion dynamics significantly when the reduced mass ratio was used, while the interplay between the electron and ion dynamics became different depending on the rescaling methods in the case of the real mass ratio. Another simulation test with much enhanced external electric field results in similar mass ratio dependence. The present simulation results clearly show that the reduced mass ratio should be used cautiously in PIC simulations as the electron dynamics can modify the ion instabilities significantly by affecting the ion motions.« less
  • Laboratory experiments have been performed that show the effect on the electron temperature of inserting a spherical conducting model, larger than the Debye length, into a free-streaming high-energy (1 kv) unmagnetized hydrogen plasma. These experiments are the first electron temperature experiments conducted at energies and compositions directly relevant to solar wind and astrophysical plasma phenomena. The incident plasma parameters were held constant. A large number of axial profiles of the electron temperature ratios T/sub e//sub in// T/sub e//sub out/ behind the model downstream in the model wake are presented. A rigorous statistical approach is used in the analysis of themore » electron temperature ratio data in both our experimental laboratory data and in our reanalysis of the published data of others. The following new results ae obtained: (1) In energetic plasma flow there is no overall temperature enhancement in the near wake since the best fit to the T/sub e//sub i/n/ T/sub e//sub out/ data is a horizontal straight line having a mean value of 1.05; (2) No statistically significant electron temperature enhancement peaks or depressions exist in the near-wake region behind a model at zero potential in a high-energy plasma even at distances less than or equal to Ma, where M is the acoustic Mach number and a is the model radius. This implies a ''filling in'' of electrons in the wake region which may be due to the higher mobility of these energetic electrons. This mechanism may permit the solar wind electrons to significantly contribute to the maintenance of the nightside ionosphere at Venus.« less
  • The central physical conditions of lunar-sized masses of imperfect gas are computed. It is shown that the physical conditions at the interface of a solid central mass and surrounding gas and those at the center of a gas mass are the same, to a first approximation, if the solid mass is of the order of 1/300 the total mass of the sphere. The relevance of these conditions to the condensation of solids and their subsequent remelting is discussed. (auth)
  • The propagation of an intense relativistic electron beam through a gas that is self-ionized by the beam's space charge and wakefields is examined analytically and with 3D particle-in-cell simulations. Instability arises from the coupling between a beam and the offset plasma channel it creates when it is perturbed. The traditional electron hose instability in a preformed plasma is replaced with this slower growth instability depending on the radius of the ionization channel compared to the electron blowout radius. A new regime for hose stable plasma wakefield acceleration is suggested.