Finite beta effects on low- and high-frequency magnetosonic waves in a two-ion-species plasma

Toida, Makoto; Aota, Yukio

doi:10.1063/1.4817169

Cited by 3 publications

(8 citation statements)

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“…For the sake of completeness we also derive the general multifluid dispersion relation for perpendicular waves from the linearized continuity and momentum equations, which was not included in [Toida and Aota, 2013]. We start from the general dispersion relation, see, e.g., in Baumjohann and Treumann [1996],…”

Section: Appendix B: Derivation Of the Phase Velocity Of Solitons Andmentioning

confidence: 99%

“…The pickup ion shock appears as a small jump in the magnetic field, which is clearly seen at a distance of 10 5 km upstream of the thermal ion shock for the simulation with n PUI /n SW = 1 (cyan line). Since the nonlinear oscilliton wave in the low-frequency fast mode F SW has a maximum amplitude [Toida and Aota, 2013], the quasi-stationary waves can steepen into a discontinuity, also known as "shocklet," if the amplitude becomes larger than the maximum amplitude. Such nonlinear steepening, or sudden small jump in the magnetic field, is seen at the second peak of each trailing wave train plotted in Figure 3a.…”

Section: 1002/2015ja021437mentioning

confidence: 99%

“…The nonlinear growth rate and the full analytical solution of the oscilliton can be obtained from the nonlinear Korteweg-de Vries equation of dispersive Eulerian fluids [Biskamp, 1973;Hoefer, 2014]. The growth rate of the nonlinear low-frequency fast mode in a three-fluid model has been derived analytically by Toida and Aota [2013], and it has been shown that the low-frequency fast mode has a maximum amplitude.…”

Section: Appendix B: Derivation Of the Phase Velocity Of Solitons Andmentioning

confidence: 99%

“…In case of three fluids, i.e., pickup ions, thermal solar wind ions and electrons, equation (B20) yields a secondorder polynomial equation for ω 2 as given in [Toida and Aota, 2013]:…”

Section: 1002/2015ja021437mentioning

confidence: 99%

“…In case of three fluids, i.e., thermal solar wind ions, pickup ions, and electrons, equation (11) reduces to a second-order polynomial equation in ω 2 (see equations (B21)-(B25); also given by Toida and Aota [2013]), which can be solved analytically. There are two linear plane wave solutions: a low-frequency fast mode and a high-frequency fast mode (see equations (B26) and (B27)).…”

Section: Introductionmentioning

confidence: 99%

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Constraining the pickup ion abundance and temperature through the multifluid reconstruction of the Voyager 2 termination shock crossing

et al. 2015

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Voyager 2 observations revealed that the hot solar wind ions (the so‐called pickup ions) play a dominant role in the thermodynamics of the termination shock and the heliosheath. The number density and temperature of this hot population, however, have remained unknown, since the plasma instrument on board Voyager 2 can only detect the colder thermal ion component. Here we show that due to the multifluid nature of the plasma, the fast magnetosonic mode splits into a low‐frequency fast mode and a high‐frequency fast mode. The coupling between the two fast modes results in a quasi‐stationary nonlinear wave mode, the “oscilliton,” which creates a large‐amplitude trailing wave train downstream of the thermal ion shock. By fitting multifluid shock wave solutions to the shock structure observed by Voyager 2, we are able to constrain both the abundance and the temperature of the undetected pickup ions. In our three‐fluid model, we take into account the nonnegligible partial pressure of suprathermal energetic electrons (0.022–1.5 MeV) observed by the Low‐Energy Charged Particle Experiment instrument on board Voyager 2. The best fitting simulation suggests a pickup ion abundance of 20 ± 3%, an upstream pickup ion temperature of 13.4 ± 2 MK, and a hot electron population with an apparent temperature of ~0.83 MK. We conclude that the actual shock transition is a subcritical dispersive shock wave with low Mach number and high plasma β.

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Section: Appendix B: Derivation Of the Phase Velocity Of Solitons Andmentioning

confidence: 99%

Section: 1002/2015ja021437mentioning

confidence: 99%

Section: Appendix B: Derivation Of the Phase Velocity Of Solitons Andmentioning

confidence: 99%

“…In case of three fluids, i.e., pickup ions, thermal solar wind ions and electrons, equation (B20) yields a secondorder polynomial equation for ω 2 as given in [Toida and Aota, 2013]:…”

Section: 1002/2015ja021437mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Constraining the pickup ion abundance and temperature through the multifluid reconstruction of the Voyager 2 termination shock crossing

et al. 2015

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Dispersive Fast Magnetosonic Waves and Shock‐Driven Compressible Turbulence in the Inner Heliosheath

et al. 2020

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The solar wind in the inner heliosheath beyond the termination shock (TS) is a nonequilibrium collisionless plasma consisting of thermal solar wind ions, suprathermal pickup ions, and electrons. In such multi-ion plasma, two fast magnetosonic wave modes exist, the low-frequency fast mode and the high-frequency fast mode. Both fast modes are dispersive on fluid and ion scales, which results in nonlinear dispersive shock waves. We present high-resolution three-fluid simulations of the TS and the inner heliosheath up to a few astronomical units (AU) downstream of the TS. We show that downstream propagating nonlinear fast magnetosonic waves grow until they steepen into shocklets, overturn, and start to propagate backward in the frame of the downstream propagating wave. The counterpropagating nonlinear waves result in 2-D fast magnetosonic turbulence, which is driven by the ion-ion hybrid resonance instability. Energy is transferred from small scales to large scales in the inverse cascade range, and enstrophy is transferred from large scales to small scales in the direct cascade range. We validate our three-fluid simulations with in situ high-resolution Voyager 2 magnetic field observations in the inner heliosheath. Our simulations reproduce the observed magnetic turbulence spectrum with a spectral slope of −5/3 in frequency domain. However, the fluid-scale turbulence spectrum is not a Kolmogorov spectrum in wave number domain because Taylor's hypothesis breaks down in the inner heliosheath. The magnetic structure functions of the simulated and observed turbulence follow the Kolmogorov-Kraichnan scaling, which implies self-similarity. The Voyager spacecraft are the first man-made objects to cross the TS (termination shock Stone et al., 2005, 2008), where the solar wind becomes subfast magnetosonic due to the interaction with the local interstellar medium. Voyager 2 observations revealed that classical single-fluid magnetohydrodynamic (MHD) or multispecies single-fluid MHD models (

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A theoretical study for parallel electric field in nonlinear magnetosonic waves in three-component plasmas

Toida

2016

Physics of Plasmas

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The electric field parallel to the magnetic field in nonlinear magnetosonic waves in three component plasmas (two-ion-species plasma and electron-positron-ion plasma) is theoretically studied based on a three-fluid model. In a two-ion-species plasma, a magnetosonic mode has two branches, high-frequency mode and low-frequency mode. The parallel electric field E k and its integral along the magnetic field, F ¼ À Ð E k ds, in the two modes propagating quasiperpendicular to the magnetic field are derived as functions of the wave amplitude and the density ratio and cyclotron frequency ratio of the two ion species. The theory shows that the magnitude of F in the high-frequency-mode pulse is much greater than that in the low-frequency-mode pulse. Theoretical expressions for E k and F in nonlinear magnetosonic pulses in an electron-positronion plasma are also obtained under the assumption that the wave amplitudes are in the range of ðm e =m i Þ 1=2 < < 1, where m e =m i is the electron to ion mass ratio.

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Finite beta effects on low- and high-frequency magnetosonic waves in a two-ion-species plasma

Cited by 3 publications

References 17 publications

Constraining the pickup ion abundance and temperature through the multifluid reconstruction of the Voyager 2 termination shock crossing

Constraining the pickup ion abundance and temperature through the multifluid reconstruction of the Voyager 2 termination shock crossing

Dispersive Fast Magnetosonic Waves and Shock‐Driven Compressible Turbulence in the Inner Heliosheath

A theoretical study for parallel electric field in nonlinear magnetosonic waves in three-component plasmas

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