Non-stationarity of the quasi-perpendicular bow shock: comparison between Cluster observations and simulations

Comişel, H.; Scholer, M.; Souček, J.; Matsukiyo, Shuichi

doi:10.5194/angeo-29-263-2011

Cited by 26 publications

(39 citation statements)

References 21 publications

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“…Multiple magnetic fluctuations in and around collisionless shock waves have been shown to be consistent with magnetosonic-whistler waves, and these fluctuations are predicted to have multiple sources including but not limited to dispersive radiation [e.g., Tidman and Northrop, 1968;Kennel et al, 1985;Krasnoselskikh et al, 2002], diffuse ions [e.g., Scholer et al, 2003;Tsubouchi and Lembège, 2004], reflected gyrating ion beams [e.g., Wu et al, 1983;Riquelme and Spitkovsky, 2011;Comişel et al, 2011], field-aligned ion beams [e.g., Akimoto et al, 1993], and streaming and anisotropic electron velocity distributions [e.g., Sentman et al, 1983]. Theory [e.g., Wu et al, 1983;Cairns and McMillan, 2005] predicts that they can stochastically accelerate electrons parallel to B o and heat ions perpendicular to B o when propagating at highly oblique angles, which has been supported by observations [e.g., Wilson et al, 2012].…”

Section: Low-frequency Wavesmentioning

confidence: 99%

Quantified energy dissipation rates in the terrestrial bow shock: 2. Waves and dissipation

et al. 2014

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Key Points:• Microscopic wave-particle interactions can regulate macroscopic shock structure • High-frequency large-amplitude waves are ubiquitous in collisionless shocks • Wave-particle interactions are the end result of nearly all dissipation pathways AbstractWe present the first quantified measure of the energy dissipation rates, due to wave-particle interactions, in the transition region of the Earth's collisionless bow shock using data from the Time History of Events and Macroscale Interactions during Substorms spacecraft. Our results show that wave-particle interactions can regulate the global structure and dominate the energy dissipation of collisionless shocks. In every bow shock crossing examined, we observed both low-frequency (<10 Hz) and high-frequency (≳10 Hz) electromagnetic waves throughout the entire transition region and into the magnetosheath. The low-frequency waves were consistent with magnetosonic-whistler waves. The high-frequency waves were combinations of ion-acoustic waves, electron cyclotron drift instability driven waves, electrostatic solitary waves, and whistler mode waves. The high-frequency waves had the following: (1) peak amplitudes exceeding B ∼ 10 nT and E ∼ 300 mV/m, though more typical values were B ∼ 0.1-1.0 nT and E ∼ 10-50 mV/m; (2) Poynting fluxes in excess of 2000 μW m −2 (typical values were ∼ 1-10 μW m −2 ); (3) resistivities > 9000 Ω m; and (4) associated energy dissipation rates > 10 μW m −3 . The dissipation rates due to wave-particle interactions exceeded rates necessary to explain the increase in entropy across the shock ramps for ∼90% of the wave burst durations. For ∼22% of these times, the wave-particle interactions needed to only be ≤ 0.1% efficient to balance the nonlinear wave steepening that produced the shock waves. These results show that wave-particle interactions have the capacity to regulate the global structure and dominate the energy dissipation of collisionless shocks.

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Section: Low-frequency Wavesmentioning

confidence: 99%

Quantified energy dissipation rates in the terrestrial bow shock: 2. Waves and dissipation

et al. 2014

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“…However, it has been argued by Krasnoselskikh et al (2013) that the artificial values of the electron plasma-to-electron cyclotron frequency ratio, necessitated by the simulations (e.g. Comişel et al 2011), produce electric fields in the simulations at least two orders of magnitude larger than those observed in heliospheric shocks. This underlines the importance of interpreting simulation results and the importance of validation against observations.…”

Section: Introductionmentioning

confidence: 99%

“…For example, Comişel et al (2011) performed 1-D PIC simulations and made comparisons with the same shock crossing studied by Lobzin et al (2007). Based on the simulation results, they concluded that the high-frequency fluctuations were due to the modified two-stream instability (MTSI), rather than the whistler gradient catastrophe model of Krasnoselskikh et al (2002).…”

Section: Introductionmentioning

confidence: 99%

Microstructure in two- and three-dimensional hybrid simulations of perpendicular collisionless shocks

et al. 2016

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Supercritical collisionless perpendicular shocks have an average macrostructure determined primarily by the dynamics of ions specularly reflected at the magnetic ramp. Within the overall macrostructure, instabilities, both linear and nonlinear, generate fluctuations and microstructure. To identify the sources of such microstructure, high-resolution two-and three-dimensional simulations have been carried out using the hybrid method, wherein the ions are treated as particles and the electron response is modelled as a massless fluid. We confirm the results of earlier two-dimensional (2-D) simulations showing both field-parallel aligned propagating fluctuations and fluctuations carried by the reflected-gyrating ions. In addition, it is shown that, for 2-D simulations of the shock coplanarity plane, the presence of short-wavelength fluctuations in all magnetic components is associated with the ion Weibel instability driven at the upstream edge of the foot by the reflected-gyrating ions. In 3-D simulations we show for the first time that the dominant microstructure is due to a coupling between field-parallel propagating fluctuations in the ramp and the motion of the reflected ions. This results in a pattern of fluctuations counter-propagating across the surface of the shock at an angle inclined to the magnetic field direction, due to a combination of field-parallel motion at the Alfvén speed of the ramp and motion in the sense of gyration of the reflected ions.

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“…This is mainly due to most studies of shock crossings being near the Earth where the Mach numbers typically range from low to modest (M A = 2-8). While some observations have been reported at Earth's bow shock [Lobzin et al, 2007], they remain open to interpretation [Comisel et al, 2011].…”

Section: Introductionmentioning

confidence: 99%

The Near-Saturn Magnetic Field Environment

Sulaiman

2017

Springer Theses

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Shock waves exist throughout the universe and are fundamental to understanding the nature of collisionless plasmas. The complex coupling between charged particles and electromagnetic fields in plasmas give rise to a whole host of mechanisms for dissipation and heating across shock waves, particularly at high Mach numbers. While ongoing studies have investigated these process extensively both theoretically and via simulations, their observations remain few and far between. This thesis presents a study of very high Mach number shocks in a parameter space that has been poorly explored and identifies reformation using in situ magnetic field observations from the This non-axisymmetry is revealed to have an impact in the rotation of the magnetic field and is significant enough to influence the magnetic shear at the magnetopause.

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Non-stationarity of the quasi-perpendicular bow shock: comparison between Cluster observations and simulations

Cited by 26 publications

References 21 publications

Quantified energy dissipation rates in the terrestrial bow shock: 2. Waves and dissipation

Quantified energy dissipation rates in the terrestrial bow shock: 2. Waves and dissipation

Microstructure in two- and three-dimensional hybrid simulations of perpendicular collisionless shocks

The Near-Saturn Magnetic Field Environment

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