OGO 5 observations of electrostatic turbulence in bow shock magnetic structures

Fredricks, R. W.; Crook, G. M.; Kennel, C. F.; Green, I. M.; Scarf, F. L.; Coleman, Paul J.; Russell, C. T.

doi:10.1029/ja075i019p03751

Cited by 99 publications

(25 citation statements)

References 18 publications

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“…Initial studies of turbulence at the bow shock [e.g., Fredricks et al, 1970] used time-averaged spectral data and showed the presence of two strongly enhanced spectral components: electromagnetic waves at <200 Hz and electrostatic waves from 200 to 800 Hz. Part of the electromagnetic spectrum was identified with fluxgate magnetometer data on IMP 6 to be composed of whistler mode waves by Fairfield [1974].…”

Section: Introductionmentioning

confidence: 99%

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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Section: Introductionmentioning

confidence: 99%

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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“…It is evident that the average electric field polarizatio n is nearly aligned with the magnetic field vector direction (¢B -¢p ~ 10°); the frequency and average polarizati on therefore identify the noise as electron plasma oscillatio ns [Fredricks et al, 1968[Fredricks et al, , 1970bROdriguez and Gurnett, 1975]. The spectrum of electron plasma oscillation s at about 2219:00 UT (20 seconds before the rapid-samp le data of Figure 14 was obtained) is sharply peaked at the electron plasma frequency near 16.5 kHz.…”

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confidence: 99%

Correlation of Bow Shock Plasma Wave Turbulence with Solar Wind Parameters

Rodriguez¹,

Gurnett²

1976

J. Geophys. Res.

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The rms field strengths of electrostatic and electromagnetic turbulence in the earth's bow shock, measured in the frequency range 20 Hz to 200 kHz with the Imp 6 satellite, are found to correlate with specific solar wind parameters measured upstream of the bow shock. The largest rms field strengths of electrostatic turbulence (200 Hz to 4 kHz) occur when the upstream electron to proton temperature ratio Te/Tp is large and when the proton temperature Tp is small, an indication that the mechanism for generating electrostatic turbulence in the bow shock is more efficient when lower upstream proton temperatures occur. No substantial correlation is found between the rms field strengths of electrostatic turbulence and three upstream parameters commonly used to classify the magnetohydrodynamic structure of the turbulent bow shock: the Alfvén Mach number MA, the ratio of particle pressure to magnetic field pressure β, and the shock normal angle . The strong correlation with Te/Tp and Tp and the lack of strong correlation with MA,β, and indicate that the strength of electrostatic turbulence in the bow shock is determined by the kinetic properties of the solar wind plasma rather than by its fluid properties. The largest rms field strengths for electromagnetic turbulence (20 Hz to 4 kHz) occur when the upstream particle density N is large and when the shock normal angle is closer to 90°, this result supporting a previous conclusion that whistler waves comprise the electromagnetic turbulence in the bow shock. Electric field turbulence, composed of both electrostatic and electromagnetic fluctuations, correlates with the upstream parameters Te/Tp, Tp, and in such a way as to imply that mode coupling occurs between electrostatic and electromagnetic waves. A broad spectrum of high‐frequency (3–30 kHz) electrostatic turbulence typically observed in the leading edge of the bow shock is interpreted as indicating the region of electron heating. Deeper within the shock transition the intensity of low‐frequency (<3 kHz) electrostatic turbulence greatly increases to form a broad peak, centered between 200 and 800 Hz, and is interpreted as corresponding to the region of maximum proton heating. The characteristic development of the electric field spectrum through the shock transition indicates that strong coupling exists between the electron and proton heating processes.

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“…Large amplitude hydromagnetic waves are found in the diffuse proton zone [Paschmann et al, 1979;Greenstadt et al, 1980;Hoppe et al, 1981]. In addition, whistler waves [Fairfield, 1974;Anderson et al, 1981;Hoppe et al, 1981], electron plasma oscillations [Scarf et al 1971;Anderson et al, 1981], and ion acoustic waves [Scarf et al, 1970;Rodriquez and Gurnett, 1975;Anderson et al, 1981] are found upstream on bow shock-connected field lines.…”

Section: Superthermal Electron and Ion Distributions Become Progres-mentioning

confidence: 99%

Nonlocal plasma turbulence associated with interplanetary shocks

Kennel¹,

Scarf²,

Coroniti³

et al. 1982

J. Geophys. Res.

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The plasma wave instrument on ISEE 3 has detected regions of plasma turbulence that extend several tenths of an astronomical unit upstream or downstream of inteplanetary shocks. The plasma waves fall into four categories. Highly impulsive 1‐ 10‐kHz electric field bursts were found hours upstream of quasi‐parallel interplanetary shocks. On occasion their average and peak amplitudes increased monotonically until the shock crossing, at which time they were suppressed. A lower frequency electric field (0.1–1 kHz) component was enhanced at nearly all shocks and persisted downstream. Broadband low‐frequency (typically <178 Hz) magnetic fluctuations increased at, and persisted hours downstream of, every interplanetary shock in our sample. A smooth high‐frequency continuum, near and above the local electron plasma frequency, was enhanced at, and persisted well downstream of, every interplanetary shock we studied. Impulsive electron plasma wave bursts were occasionally found near the shocks. The shock‐associated plasma waves we found to extend over large spatial scales are similar to those found previously in local studies of interplanetary shocks. While no single interplanetary shock showed every effect, the ensemble of shocks contained at least one example of each type of plasma wave found upstream of the earth's bow shock. The 1‐ to 10‐kHz spectra upstream of interplanetary shocks and the earth's bow shock are similar. The low‐frequency electric and magnetic fluctuations downstream of interplanetary shocks and the bow shock have similar spectra. They seem to be ubiquitous features of flowing plasmas made turbulent by a shock.

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OGO 5 observations of electrostatic turbulence in bow shock magnetic structures

Cited by 99 publications

References 18 publications

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

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

Correlation of Bow Shock Plasma Wave Turbulence with Solar Wind Parameters

Nonlocal plasma turbulence associated with interplanetary shocks

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