Microscale instabilities in stream interaction regions

Eviatar, A.; Goldstein, M. L.

doi:10.1029/ja085ia02p00753

Cited by 3 publications

(4 citation statements)

References 41 publications

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“…is similar to what has been observed by Helios at 0.3-1 AU from the Sun [Beinroth and Neubauer, 1981]. Eviatar and Goldstein [1980] discussed theoretically several plasma instabilities which were associated with stream interfaces and the compression region. They found that beyond I AU, the possible range of frequencies excited in these regions extends from the lower hybrid (due to the modified twostream instability) through the ion acoustic frequency range to harmonics of the electron cyclotron frequency.…”

Section: Summary Of the Observationssupporting

confidence: 85%

Very low frequency waves in the heliosphere: Ulysses observations

Lin¹,

Kellogg²,

MacDowall³

et al. 1998

J. Geophys. Res.

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Section: Summary Of the Observationssupporting

confidence: 85%

Very low frequency waves in the heliosphere: Ulysses observations

Lin¹,

Kellogg²,

MacDowall³

et al. 1998

J. Geophys. Res.

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“…This instability had been studied earlier in the electrostatic limit by Stepanov [1973] reported detailed studies of growth rate variations with 0; they showed that at v o • v e, the maximum growth rate typically occurs at Electromagnetic or nonzero fi effects on the modified two-_ stream instability were first examined in detail by Lemons and Gary [1977], who showed that as fie is increased, Ym decreases but also shifts to larger values of k:/k. This subject was pursued in greater detail by Eviatar and Goldstein [1980] and Wu et al [1983]. In particular, the latter demonstrated that the modified two-stream instability (or, in their terminology, the "kinetic cross-field streaming instability") is not stabilized by electromagnetic effects' since the •e stabilization criterion of McBride and Ott [1972] requires nonresonant electrons and 0 very close to re/2, it may apply to the ion/ion lower hybrid instability but not to the modified two-stream instability.…”

supporting

confidence: 68%

“…However, it may be possible to use existing particle data to indirectly infer the relative {mportance of the two electron/ion instabilities in the following A recent experimental study [Bavassano-Cattaneo et al, 1986] has demonstrated the existence of a magnetic foot at some interplanetary shocks. We expect that these structures are also due to the presence of ions reflected from the shock and that our theory (as well as the earlier work of Papadopoulos [1973] and Eviatar and Goldstein [1980]) should apply to the generation of lower hybrid frequency noise at interplanetary shocks as well.…”

Section: In This Papermentioning

confidence: 75%

“…Since these instabilities are fundamenmum growth out of the Bo-V o plane. More recent theories of tally electrostatic in nature, it is simpler and more elegant to the ion/ion lower hybrid instability include the electrostatic first establish their properties at zero •e and then examine studies of Roth et al [1983] and Barbosa [1986], as well as electromagnetic studies by Eviatar and Goldstein [1980] and Wu et al [1983].…”

mentioning

confidence: 99%

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Ion/ion and electron/ion cross‐field instabilities near the lower hybrid frequency

Gary¹,

Tokar²,

Winske³

1987

J. Geophys. Res.

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Instabilities near the lower hybrid frequency are investigated by numerically solving the linear Vlasov electromagnetic dispersion equation. The configuration is that of two unmagnetized ion components, a less dense beam and a more dense core, streaming across a uniform magnetic field with magnetized electrons in the zero momentum frame. All three components are considered to have similar temperatures. This paper studies the parametric dependences of maximum growth rate for three distinct modes: the electron/ion beam modified two-stream instability, the electron/ion core modified two-stream instability, and the ion/ion lower hybrid instability. In the electrostatic limit the electron/beam instability has a lower threshold and larger growth rate than its electron/core counterpart. Except near equal beam and core densities, our results also suggest that the electron/beam instability has a maximum growth rate that is equal to or greater than that of the ion/ion instability for all plasma beta values. Thus the electron/beam modified two-stream instability is a likely candidate to account for the presence of lower hybrid fluctuations in the foot of the earth's bow shock at low beta. INTRODUCTION bow shock [Wu et al., 1984' Winske et al., 1985]. We consider Collisionless shocks of sufficiently high Mach number re-the following homogeneous plasma configuration' two unflect a significant fraction of the incident ions as a means of magnetized ion components, a more dense core and a less dissipation [e.g., Tidman and Krall, 1971, chapter 3]. There-dense beam, streaming across a uniform magnetic field B o, in the presence of a magnetized electron component at rest in the fore Auer et al. [1971] and Papadopoulos et al. [1971a] proposed that instabilities driven by the counterstreaming of the zero momentum frame. In this configuration there are at least incident ions and the reflected ions would develop upstream of six distinct instabilities. The high-frequency trio consisting of the shock. Both observations [Paschmann et al., 1982; Sckopke the ion/ion acoustic, the electron/ion acoustic, and the elecet al., 1983] and computer simulations [Papadopoulos et al., 1971b' Leroy et al., 1981, 1982] demonstrated the correlation between reflected ions which gyrate in front of the shock and a "foot" signature in the magnetic field magnitude at supercritical shocks. Furthermore, it has now been shown that there is a correlation between enhanced electrostatic fluctuations in both the lower hybrid and the ion acoustic frequency regimes and the presence of a foot at the earth's bow shock [Vaisber•I et al., 1982, 1983; Gurnett, 1985' Greenstadt and Mellott, 1987' Mellott and Greenstadt, 1986]. The recent work of Mellott and Greenstadt [1986] demonstrates not only that enhanced lower hybrid fluctuations at the earth's bow shock are correlated with the upstream turnaround distance of specularly reflected ions but also that the fluctuating field energy density typically increases through the foot region and peaks in the shock ramp. In this pa...

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