Microturbulence in the electron cyclotron frequency range at perpendicular supercritical shocks

Muschietti, L.; Lembège, Bertrand

doi:10.1002/jgra.50224

Cited by 54 publications

(86 citation statements)

References 24 publications

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“…The total relative density of the reflected ions, however, ranged from ∼20 to 40% immediately upstream of 9 of the 11 bow shock ramps, but was ∼1-2% for two crossings (see section 3.1 in Paper I). The important thing to recognize is that particle reflection is inherently reversible but can generate instabilities that radiate waves which can then dissipate energy [e.g., Matsukiyo and Scholer, 2006;Muschietti and Lembège, 2013]. We observed evidence of at least two of these instabilities: the ECDI [e.g., Breneman et al, 2013] and the magnetic fluctuations associated with diffuse ions (which have been generalized to magnetosonic-whistler waves herein) [e.g., Wilson et al, 2009Wilson et al, , 2013b].…”

Section: Discussionmentioning

confidence: 96%

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: Discussionmentioning

confidence: 96%

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

et al. 2014

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“…This can result in a strong interaction between electron and ion species. A recent particle-in-cell simulation by Muschietti and Lembège [2013], designed for conditions that allow the growth of small-scale waves (realistic values of the proton to electron mass ratio, the plasma to electron cyclotron frequency ratio, etc. ), has indicated that the ECDI may be much more important than previously thought at the bow shock transition region.…”

Section: Comparison With Traditional Bernstein Wavesmentioning

confidence: 99%

“…[28] The simulations by Muschietti and Lembège [2013] indicated that the ECDI has an inverse cascade of harmonics with time, i.e., the frequency range of unstable harmonics decreases with time. Our observations indicate that the lower harmonics tend to dominate over higher harmonics, suggesting that large amplitude ECDI waves are formed during later stages of ECDI evolution.…”

Section: Comparison With Traditional Bernstein Wavesmentioning

confidence: 99%

“…The only prior observation was presented by Wilson et al [2010], who reported ECDI waves from Wind burst data at an interplanetary shock. Future validation of the ECDI at the bow shock and magnetosheath is important because, as pointed out by Muschietti and Lembège [2013], ECDI waves, though they carry only a small fraction of the energy density of the electron and ion beams, are expected to be effective at transferring energy and momentum between the species, ultimately resulting in energy dissipation. True validation of the ECDI may be addressed from a more detailed analysis of the Wind burst data set in conjunction with particle data.…”

Section: Comparison With Traditional Bernstein Wavesmentioning

confidence: 99%

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STEREO and Wind observations of intense cyclotron harmonic waves at the Earth's bow shock and inside the magnetosheath

et al. 2013

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[1] We present the first observations of electron cyclotron harmonic waves at the Earth's bow shock from STEREO and Wind burst waveform captures. These waves are observed at magnetic field gradients at a variety of shock geometries ranging from quasi-parallel to nearly perpendicular along with whistler mode waves, ion acoustic waves, and electrostatic solitary waves. Large amplitude cyclotron harmonic waveforms are also observed in the magnetosheath in association with magnetic field gradients convected past the bow shock. Amplitudes of the cyclotron harmonic waves range from a few tens to more than 500 mV/m peak-peak. A comparison between the short (15 m) and long (100 m) Wind spin plane antennas shows a similar response at low harmonics and a stronger response on the short antenna at higher harmonics. This indicates that wavelengths are not significantly larger than 100 m, consistent with the electron cyclotron radius. Waveforms are broadband and polarizations are distinctively comma-shaped with significant power both perpendicular and parallel to the magnetic field. Harmonics tend to be more prominent in the perpendicular directions. These observations indicate that the waves consist of a combination of perpendicular Bernstein waves and field-aligned waves without harmonics. A likely source is the electron cyclotron drift instability which is a coupling between Bernstein and ion acoustic waves. These waves are the most common type of high-frequency wave seen by STEREO during bow shock crossings and magnetosheath traversals and our observations suggest that they are an important component of the high-frequency turbulent spectrum in these regions.

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“…It should be noted that the ECDI is dominant in a lowerbeta plasma and that the frequency ratio affects the growth rate of the ECDI (Muschietti and Lembege, 2013). The ECDI can disturb the generation of the MTSI through nonlinear saturation as seen in Run A.…”

Section: Discussion On the Simulation Resultsmentioning

confidence: 99%

Periodic self-reformation of rippled perpendicular collisionless shocks in two dimensions

Umeda

Daicho

2018

Ann. Geophys.

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Abstract. Large-scale two-dimensional (2-D) full particlein-cell (PIC) simulations are carried out for studying periodic self-reformation of a supercritical collisionless perpendicular shock with an Alfvén-Mach number M A ∼ 6.Previous self-consistent one-dimensional (1-D) hybrid and full PIC simulations have demonstrated that the periodic reflection of upstream ions at the shock front is responsible for the formation and vanishing of the shock-foot region on a timescale of the local ion cyclotron period, which was defined as the reformation of (quasi-)perpendicular shocks.The present 2-D full PIC simulations with different ionto-electron mass ratios show that the dynamics at the shock front is strongly modified by large-amplitude ion-scale fluctuations at the shock overshoot, which are known as ripples.In the run with a small mass ratio, the simultaneous enhancement of the shock magnetic field and the reflected ions take place quasi-periodically, which is identified as the reformation. In the runs with large mass ratios, the simultaneous enhancement of the shock magnetic field and the reflected ions occur randomly in time, and the shock magnetic field is enhanced on a timescale much shorter than the ion cyclotron period.These results indicate a coupling between the shock-front ripples and electromagnetic microinstabilities in the foot region in the runs with large mass ratios.

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Microturbulence in the electron cyclotron frequency range at perpendicular supercritical shocks

Cited by 54 publications

References 24 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

STEREO and Wind observations of intense cyclotron harmonic waves at the Earth's bow shock and inside the magnetosheath

Periodic self-reformation of rippled perpendicular collisionless shocks in two dimensions

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