Fine structure of Langmuir waves observed upstream of the bow shock at Venus

<div>The Sun frequently accelerates near-relativistic electron beams that travel out through the solar corona and interplanetary space. Interacting with their plasma environment, these beams produce type III radio bursts, the brightest astrophysical radio sources detected by humans. The formation and motion of type III fine frequency structures is a puzzle but is commonly believed to be related to plasma turbulence in the solar corona and solar wind. Combining a theoretical framework with kinetic simulations and high-resolution radio type III observations, we quantitatively show that the fine structures are caused by the moving intense clumps of Langmuir waves in a turbulent medium. Our results show how type III fine structure can be used to remotely analyse the intensity and spectrum of compressive density fluctuations, and can infer ambient temperatures in astrophysical plasma, both significantly expanding the current diagnostic potential of solar radio emission.</div><div>&#160;</div>

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

Annales Geophysicae ◽

10.5194/angeo-26-2899-2008 ◽

2008 ◽

Vol 26 (9) ◽

pp. 2899-2910 ◽

Cited By ~ 10

Author(s):

V. V. Lobzin ◽

V. V. Krasnoselskikh ◽

K. Musatenko ◽

T. Dudok de Wit

Keyword(s):

Electric Field ◽

Shock Front ◽

Energetic Electron ◽

Bow Shock ◽

Langmuir Waves ◽

Shock Surface ◽

High Frequency Electric Field ◽

Earth’S Bow Shock ◽

Hidden Periodicities ◽

Field Fluctuations

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 fBi<f<fBi, where fBi is the proton gyrofrequency upstream of the shock, and shows that the probability to observe such a nonstationarity increases with Mach number. The profiles observed aboard different spacecraft and the dominating frequencies of the periodicities are usually different. Hence nonstationarity and/or rippling seem to be rather irregular both in space and time rather than resembling a quasiregular wave propagating on the shock surface.

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Spatial distribution of Langmuir waves observed upstream of Saturn's bow shock by Cassini

Journal of Geophysical Research Space Physics ◽

10.1002/2016ja022912 ◽

2016 ◽

Vol 121 (8) ◽

pp. 7771-7784 ◽

Cited By ~ 3

Author(s):

D. Píša ◽

O. Santolík ◽

G. B. Hospodarsky ◽

W. S. Kurth ◽

D. A. Gurnett ◽

...

Keyword(s):

Spatial Distribution ◽

Bow Shock ◽

Langmuir Waves

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Fine structure of Langmuir waves produced by a solar electron event

Journal of Geophysical Research Atmospheres ◽

10.1029/92ja02838 ◽

1993 ◽

Vol 98 (A4) ◽

pp. 5631-5637 ◽

Cited By ~ 79

Author(s):

D. A. Gurnett ◽

G. B. Hospodarsky ◽

W. S. Kurth ◽

D. J. Williams ◽

S. J. Bolton

Keyword(s):

Fine Structure ◽

Langmuir Waves ◽

Electron Event

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Study of the fine structure of charged particles flows in the bow shock wave

Czechoslovak Journal of Physics ◽

10.1007/bf01597672 ◽

1987 ◽

Vol 37 (2) ◽

pp. 239-249

Author(s):

I. Kozák ◽

Z. Němeček ◽

J. Šafránková ◽

G. N. Zastenker

Keyword(s):

Shock Wave ◽

Fine Structure ◽

Charged Particles ◽

Bow Shock ◽

Bow Shock Wave

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Observations of the fine structure of ion distribution function at the bow shock

Advances in Space Research ◽

10.1016/s0273-1177(97)00464-x ◽

1997 ◽

Vol 20 (4-5) ◽

pp. 735-739

Author(s):

V.N. Smirnov ◽

O.L. Vaisberg ◽

L.A. Avanov ◽

A.A. Petrukovich ◽

A.A. Skalsky ◽

...

Keyword(s):

Distribution Function ◽

Fine Structure ◽

Bow Shock ◽

Ion Distribution

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Fine Structure of Platelet Interaction with a New Microcrystalline Collagen Preparation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100050305 ◽

1974 ◽

Vol 32 ◽

pp. 58-59

Author(s):

W. H. Zucker ◽

R. G. Mason

Keyword(s):

Fine Structure ◽

Platelet Aggregation ◽

Hydrochloric Acid ◽

Whole Blood ◽

Platelet Adhesion ◽

Hemostatic Agent ◽

Native Collagen ◽

Fibrillar Morphology ◽

Clinical Interest ◽

New Form

Platelet adhesion initiates platelet aggregation and is an important component of the hemostatic process. Since the development of a new form of collagen as a topical hemostatic agent is of both basic and clinical interest, an ultrastructural and hematologic study of the interaction of platelets with the microcrystalline collagen preparation was undertaken.In this study, whole blood anticoagulated with EDTA was used in order to inhibit aggregation and permit study of platelet adhesion to collagen as an isolated event. The microcrystalline collagen was prepared from bovine dermal corium; milling was with sharp blades. The preparation consists of partial hydrochloric acid amine collagen salts and retains much of the fibrillar morphology of native collagen.

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Pituitary Follicular Cells: Their Origin, Possible Function and Fate

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100050184 ◽

1974 ◽

Vol 32 ◽

pp. 34-35

Author(s):

E. Horvath ◽

K. Kovacs ◽

G. Penz ◽

C. Ezrin

Keyword(s):

Fine Structure ◽

Secretory Granules ◽

Follicular Cells ◽

Human Pituitary ◽

Rat Pituitary ◽

Pituitary Glands ◽

Junctional Complexes

Follicular structures, in the rat pituitary, composed of cells joined by junctional complexes and possessing few organelles and few, if any, secretory granules, were first described by Farquhar in 1957. Cells of the same description have since been observed in several species including man. The importance of these cells, however, remains obscure. While studying human pituitary glands, we have observed wide variations in the fine structure of follicular cells which may lead to a better understanding of their morphogenesis and significance.

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