Generation of downshifted oscillations in the electron foreshock: A loss‐cone instability

Lobzin, V. V.; Krasnoselskikh, V.; Schwartz, S. J.; Cairns, Iver H.; Lefebvre, Bertrand; Décréau, Pierrette; Fazakerley, A. N.

doi:10.1029/2005gl023563

Cited by 22 publications

(32 citation statements)

References 19 publications

(31 reference statements)

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“…This method was suggested by Lobzin et al (2003) and was previously proven to be useful in a case study of a nonstationary bow shock observed by Cluster spacecraft on 24 January 2001 at 07:05:00-07:09:00 UT. The method is based on analysis of high frequency electric field fluctuations corresponding to Langmuir, upshifted, and downshifted oscillations in the electron foreshock.…”

Section: Discussionmentioning

confidence: 99%

“…To find convincing experimental evidence of shock front rippling or wrinkling, it is desirable to follow the shock evolution during relatively long time intervals, much longer than the ion gyroperiod. Fortunately, when spacecraft are in the electron foreshock, there exists a possibility for remote sensing of the quasiperpendicular region of bow shock surface during relatively long time intervals (Lobzin et al, 2003). To this end, one can analyze high-frequency electric field fluctuations corresponding to Langmuir, upshifted, and downshifted waves.…”

Section: Data Selection and Analysis Proceduresmentioning

confidence: 99%

“…These waves are generated by superthermal electrons that were reflected from the bow shock and propagate in the sunward direction along the magnetic field lines (e.g. Filbert and Kellogg, 1979;Lacombe et al, 1985;Lobzin et al, 2005, and references therein). The deformation of the shock front should lead to significant changes of these fluxes, which in their turn result in changes of observed electric field spectra.…”

Section: Introductionmentioning

confidence: 99%

“…For example, the spacecraft separation varies in the range 100-10 000 km for Cluster mission, while the thickness of a typical quasiperpendicular shock is about 600 km. However, when spacecraft are in the electron foreshock, there exists an indirect method for remote sensing of the bow shock surface during relatively long time intervals (see Lobzin et al, 2003, and the details in the following). This method is based on analysis of high-frequency electric field fluctuations corresponding to Langmuir, upshifted, and downshifted waves.…”

Section: Introductionmentioning

confidence: 99%

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On nonstationarity and rippling of the quasiperpendicular zone of the Earth bow shock: Cluster observations

et al. 2008

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Abstract. A new method for remote sensing of the quasiperpendicular part of the bow shock surface is presented. The method is based on analysis of high frequency electric field fluctuations corresponding to Langmuir, upshifted, and downshifted oscillations in the electron foreshock. Langmuir waves usually have maximum intensity at the upstream boundary of this region. All these waves are generated by energetic electrons accelerated by quasiperpendicular zone of the shock front. Nonstationary behavior of the shock, in particular due to rippling, should result in modulation of energetic electron fluxes, thereby giving rise to variations of Langmuir waves intensity. For upshifted and downshifted oscillations, the variations of both intensity and central frequency can be observed. For the present study, WHISPER measurements of electric field spectra obtained aboard Cluster spacecraft are used to choose 48 crossings of the electron foreshock boundary with dominating Langmuir waves and to perform for the first time a statistical analysis of nonstationary behavior of quasiperpendicular zone of the Earth's bow shock. Analysis of hidden periodicities in plasma wave energy reveals shock front nonstationarity in the frequency range 0.33 f Bi

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Section: Discussionmentioning

confidence: 99%

Section: Data Selection and Analysis Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On nonstationarity and rippling of the quasiperpendicular zone of the Earth bow shock: Cluster observations

et al. 2008

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“…Recent studies by Lobzin et al (2005) of so-called downshifted oscillations have shown that different types of waves are associated with the features of the electron distribution functions; such waves are a consequence of the interaction of the shock front with the incident electrons; their frequency is typically several tens of kHz. First studies were carried out using ISEE and later with Cluster.…”

Section: Extending the Frequency Range Of Acbmentioning

confidence: 99%

AC magnetic field measurements onboard Cross-Scale: Scientific objectives and instrument design

Wit¹,

Coillot

Jannet³

et al. 2011

Planetary and Space Science

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a b s t r a c tThe ACB search-coil magnetometer for Cross-Scale will measure three components of the AC magnetic field up to 4 kHz, and one component up to 100 kHz. Turbulent and coherent magnetic field fluctuations in that frequency range play an important role in the acceleration, scattering, and thermalisation of particles. ACB will, together with the other instruments of the Cross-Scale wave consortium, allow to address the key science objectives associated with plasma waves. Here, we list some of the important issues, based on the experience drawn from Cluster, and describe the instrument.

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The Dynamic Quasiperpendicular Shock: Cluster Discoveries

Krasnoselskikh

Balikhin

Walker

et al. 2013

Microphysics of Cosmic Plasmas

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The physics of collisionless shocks is a very broad topic which has been studied for more than five decades. However, there are a number of important issues which remain unresolved. The energy repartition amongst particle populations in quasiperpendicular shocks is a multi-scale process related to the spatial and temporal structure of the electromagnetic fields within the shock layer. The most important processes take place in the close vicinity of the major magnetic transition or ramp region. The distribution of electromagnetic fields in this region determines the characteristics of ion reflection and thus defines the conditions for ion heating and energy dissipation for supercritical shocks and also the region where an important part of electron heating takes place. In other words, the ramp region determines the main characteristics of energy repartition. All of these processes are crucially dependent upon the characteristic spatial scales of the ramp and foot region provided that the shock is stationary. The process of shock formation consists of the steepening of a large amplitude nonlinear wave. At some point in its evolution the steepening is arrested by processes occurring within the shock transition. From the earliest studies of collisionless shocks these processes were identified as nonlinearity, dissipation, and dispersion. Their relative role determines the scales of electric and magnetic fields, and so control the characteristics of processes such as of ion reflection, electron heating and particle acceleration. The determination of the scales of the electric and magnetic field is one of the key issues in the physics of collisionless shocks. Moreover, it is well known that under certain conditions shocks manifest a nonstationary dynamic behaviour called reformation. It was suggested that the transition from stationary to nonstationary quasiperiodic dynamics is related to gradients, e.g. scales of the ramp region and its associated whistler waves that form a precursor wave train. This implies that the ramp region should be considered as the source of these waves. All these questions have been studied making use observations from the Cluster satellites. The Cluster project continues to provide a unique viewpoint from which to study the scales of shocks. During is lifetime the inter-satellite distance between the Cluster satellites has varied from 100 km to 10000 km allowing scientists to use the data best adapted for the given scientific objective.The purpose of this review is to address a subset of unresolved problems in collisionless shock physics from experimental point of view making use multi-point observations onboard Cluster satellites. The problems we address are determination of scales of fields and of a scale of electron heating, identification of energy source of precursor wave train, an estimate of the role of anomalous resistivity in energy dissipation process by means of measuring short scale wave fields, and direct observation of reformation process during one single shock front...

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Generation of downshifted oscillations in the electron foreshock: A loss‐cone instability

Cited by 22 publications

References 19 publications

On nonstationarity and rippling of the quasiperpendicular zone of the Earth bow shock: Cluster observations

On nonstationarity and rippling of the quasiperpendicular zone of the Earth bow shock: Cluster observations

AC magnetic field measurements onboard Cross-Scale: Scientific objectives and instrument design

The Dynamic Quasiperpendicular Shock: Cluster Discoveries

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