Microinstabilities associated with a high Mach number, perpendicular bow shock

Wu, C. S.; Winske, D.; Zhou, Yi; Tsai, S. T.; Rodriguez, P.; Tanaka, Motohiko; Papadopoulos, K.; Akimoto, Kazuhiro; Lin, C. S.; Leroy, M.; Goodrich, C. C.

doi:10.1007/bf00213958

Cited by 153 publications

(120 citation statements)

References 52 publications

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“…We have assumed a priori that electrons and protons are thermodynamically coupled only by Coulomb collisions. In fact, there are other mechanisms that can couple these particle populations and more rapidly thermalize the electrons (e.g., Wu et al 1984). Evidence of electron heating at collisionless shocks is presented by Schwartz et al (1988), who analyzed 66 terrestrial bow shock and 14 interplanetary shock crossings.…”

Section: Discussionmentioning

confidence: 99%

The Coupled Evolution of Electrons and Ions in Coronal Mass Ejection-Driven Shocks

Manchester

Holst

Tóth

et al. 2012

ApJ

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We present simulations of coronal mass ejections (CMEs) performed with a new two-temperature coronal model developed at the University of Michigan, which is able to address the coupled thermodynamics of the electron and proton populations in the context of a single fluid. This model employs heat conduction for electrons, constant adiabatic index (γ = 5/3), and includes Alfvén wave pressure to accelerate the solar wind. The Wang-Sheeley-Arge empirical model is used to determine the Alfvén wave pressure necessary to produce the observed bimodal solar wind speed. The Alfvén waves are dissipated as they propagate from the Sun and heat protons on open magnetic field lines to temperatures above 2 MK. The model is driven by empirical boundary conditions that includes GONG magnetogram data to calculate the coronal field, and STEREO/EUVI observations to specify the density and temperature at the coronal boundary by the Differential Emission Measure Tomography method. With this model, we simulate the propagation of fast CMEs and study the thermodynamics of CME-driven shocks. Since the thermal speed of the electrons greatly exceeds the speed of the CME, only protons are directly heated by the shock. Coulomb collisions low in the corona couple the protons and electrons allowing heat exchange between the two species. However, the coupling is so brief that the electrons never achieve more than 10% of the maximum temperature of the protons. We find that heat is able to conduct on open magnetic field lines and rapidly propagates ahead of the CME to form a shock precursor of hot electrons.

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Section: Discussionmentioning

confidence: 99%

The Coupled Evolution of Electrons and Ions in Coronal Mass Ejection-Driven Shocks

Manchester

Holst

Tóth

et al. 2012

ApJ

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“…Forslund et al (1970), Gary (1971), and references in the review by Wu et al (1984)). It is a variety in the sense that the instability is not driven by the whole ions drifting as a bulk, yet just by an ion beam.…”

Section: Discussionmentioning

confidence: 99%

“…Possible instabilities associated with relative drifts between the populations were analysed, mostly through studies of the dispersion relation. A review of those efforts may be found in Wu et al (1984). Although they provide useful insights into potential instabilities, those works were limited in that they considered the foot as a stationary, homogeneous plasma independent from the whole shock structure and then investigated its properties with chosen ad hoc parameters.…”

Section: Introductionmentioning

confidence: 99%

Electron cyclotron microinstability in the foot of a perpendicular shock: A self-consistent PIC simulation

Muschietti

Lembège²

2006

Advances in Space Research

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We have performed one-dimensional full particle simulations of perpendicular shocks and found that an electron cyclotron microinstability can develop in the foot during the self-reformation phase of low β i supercritical shocks. The instability is excited by the beam of reflected ions interacting with the incoming electrons. It exhibits a rapid growth, and propagates along the shock normal towards upstream. This instability, which does not require high Mach number, has a frequency comparable to the electron cyclotron frequency and a wavelength shorter than the electron inertia length. It basically results from the coupling of electron Bernstein waves with an ion beam mode carried by the reflected ions. Dispersion properties in the foot are analysed. We discuss the effects of varying parameters, in particular as the fake ion-to-electron mass ratio used in the simulations converges to more realistic values. Comparison with other microinstabilities evidenced in recent full particle simulations of shocks is outlined.

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“…A list of the waves/ instabilities that are most commonly proposed to provide significant anomalous resistivity can be found in Wu et al [1984]. Two types of waves have been of particular interest in collisionless shock energy dissipation: lower hybrid and whistler waves.…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic waves and electron anisotropies downstream of supercritical interplanetary shocks

et al. 2013

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[1] We present waveform observations of electromagnetic lower hybrid and whistler waves with f ci ≪ f < f ce downstream of four supercritical interplanetary shocks using the Wind search coil magnetometer. The whistler waves were observed to have a weak positive correlation between dB and normalized heat flux magnitude and an inverse correlation with T eh /T ec . All were observed simultaneous with electron distributions satisfying the whistler heat flux instability threshold and most with T ⊥ h /T k h > 1.01. Thus, the whistler mode waves appear to be driven by a heat flux instability and cause perpendicular heating of the halo electrons. The lower hybrid waves show a much weaker correlation between dB and normalized heat flux magnitude and are often observed near magnetic field gradients. A third type of event shows fluctuations consistent with a mixture of both lower hybrid and whistler mode waves. These results suggest that whistler waves may indeed be regulating the electron heat flux and the halo temperature anisotropy, which is important for theories and simulations of electron distribution evolution from the Sun to the Earth.

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Microinstabilities associated with a high Mach number, perpendicular bow shock

Cited by 153 publications

References 52 publications

The Coupled Evolution of Electrons and Ions in Coronal Mass Ejection-Driven Shocks

The Coupled Evolution of Electrons and Ions in Coronal Mass Ejection-Driven Shocks

Electron cyclotron microinstability in the foot of a perpendicular shock: A self-consistent PIC simulation

Electromagnetic waves and electron anisotropies downstream of supercritical interplanetary shocks

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