Spatial structures in solar wind superthermal electrons and polar rain aurora

2021 ◽  
pp. 105633
Author(s):  
Dennis Herschbach ◽  
Yongliang Zhang
Keyword(s):  
Solar Wind ◽  
Spatial Structures ◽  
Superthermal Electrons ◽  
Polar Rain

Dynamical features and spatial structures of the plasma interaction region of 67P/Churyumov–Gerasimenko and the solar wind

2015 ◽  
Vol 105 ◽  
pp. 101-116 ◽  
Author(s):  
C. Koenders ◽  
K.-H. Glassmeier ◽  
I. Richter ◽  
H. Ranocha ◽  
U. Motschmann
Keyword(s):  
Solar Wind ◽  
Interaction Region ◽  
Spatial Structures ◽  
Plasma Interaction ◽  
Dynamical Features

Bidirectional solar wind electron heat flux and hemispherically symmetric polar rain

1986 ◽  
Vol 91 (A10) ◽  
pp. 11352 ◽  
Author(s):  
J. T. Gosling ◽  
D. N. Baker ◽  
S. J. Bame ◽  
R. D. Zwickl
Keyword(s):  
Heat Flux ◽  
Solar Wind ◽  
Electron Heat ◽  
Polar Rain ◽  
Solar Wind Electron

scholarly journals Plasma flow channels at the dawn/dusk polar cap boundaries: momentum transfer on old open field lines and the roles of IMF <I>B<sub>y</sub></I> and conductivity gradients

2009 ◽  
Vol 27 (4) ◽  
pp. 1527-1554 ◽  
Author(s):  
P. E. Sandholt ◽  
C. J. Farrugia
Keyword(s):  
Solar Wind ◽  
Momentum Transfer ◽  
Open Field ◽  
Flow Channel ◽  
Polar Cap ◽  
Ionospheric Conductivity ◽  
Flow Channels ◽  
Precipitation Regimes ◽  
Polar Rain ◽  
Field Lines

Abstract. Using DMSP F13 data in conjunction with IMF data we investigate the newly discovered channels of enhanced (1.5–3 km/s) antisunward convection occurring at the dawn (06:00–09:00 MLT) or dusk (15:00–18:00 MLT) flanks of the polar cap for different combinations of IMF By polarity, hemisphere (NH/SH) and the dawn/dusk MLTs. Dawn-side cases where this flow channel appears occur for the following combinations: NH-dawn/By>0 and SH-dawn/By<0. The dusk-side cases are: NH-dusk/By<0 and SH-dusk/By>0. The flow channels are placed in the context of particle precipitation regimes/boundaries and ionospheric conductivity gradients. They are found to be threaded by "old open field lines" ("time since reconnection" >10 min) characterized by polar rain precipitation. In the dawn-side cases (NH-dawn/By>0 and SH-dawn/By<0) and in a Parker spiral field, the polar rain contains the "solar wind strahl" component. The convection enhancement is attributed to the Pedersen current closure of Birkeland current sheets (C1 and C2) in the polar cap (C1) and at the polar cap boundary (C2). The low ionospheric conductivity in the polar cap, particularly in the winter hemisphere, is compensated by an enhanced electric field driving the flow channel there. This is momentum transfer from the solar wind via dynamo action taking place in the combined current system of the high- and low-latitude boundary layers (HBL/LLBL). The conductivity gradient at the polar cap boundary contributes to establishing the convection channel and the associated enhancement of the dawn-dusk convection asymmetry extending beyond the dawn-dusk terminator during intervals of nonzero IMF By component. The HBL/LLBL-ionosphere coupling via Birkeland currents C1/C2 is a source of dawn-dusk convection asymmetry and Svalgaard-Mansurov effect which must be added to the effect of magnetic tension acting on "newly open field lines".

scholarly journals Cusp structures: combining multi-spacecraft observations with ground-based observations

2003 ◽  
Vol 21 (10) ◽  
pp. 2031-2041 ◽  
Author(s):  
K. J. Trattner ◽  
S. A. Fuselier ◽  
T. K. Yeoman ◽  
A. Korth ◽  
M. Fraenz ◽  
...  
Keyword(s):  
Solar Wind ◽  
Boundary Layers ◽  
Large Scale ◽  
Temporal Variations ◽  
Energetic Particles ◽  
Spatial Structures ◽  
Magnetospheric Physics ◽  
Convection Pattern ◽  
Radar Observations ◽  
Delay Times

Abstract. Recent simultaneous observations of cusp structures with Polar, FAST and Interball revealed remarkably similar features at spacecraft crossing the cusp. Such stable cusp structures could be observed up to several hours only during stable solar wind conditions. Their similarities led to the conclusion that for such conditions large-scale cusp structures are spatial structures related to a global ionospheric convection pattern and not the result of temporal variations in reconnection parameters. With the launch of the Cluster fleet we are now able to observe precipitating ion structures in the cusp with three spacecraft and identical instrumentation. The orbit configuration of the Cluster spacecraft allows for delay times between spacecraft of about 45 min in crossing the cusp. The compact configuration of three spacecraft at about the same altitude allows for the analysis of cusp structures in great de-tail and during changing solar wind conditions. Cluster observations on 25 July 2001 are combined with SuperDARN radar observations that are used to derive a convection pattern in the ionosphere. We found that large-scale cusp structures for this Cluster cusp crossing are in agreement with structures in the convection pattern and conclude that major cusp structures can be consistent with a spatial phenomenon.Key words. Magnetospheric physics (energetic particles, precipitating, magnetopause, cusp arid and boundary layers; solar wind-magnetosphere interactions)

Space and Time Distribution of Hard X-Ray Emission in a Loop at the Beginning of a Flare

1994 ◽  
Vol 144 ◽  
pp. 275-277
Author(s):  
M. Karlický ◽  
J. C. Hénoux
Keyword(s):  
Time Distribution ◽  
Electron Bombardment ◽  
Spatial Evolution ◽  
Superthermal Electrons ◽  
Flare Loop ◽  
X Ray ◽  
Superthermal Electron ◽  
Flare Loops ◽  
Chromospheric Evaporation ◽  
Temporal And Spatial

AbstractUsing a new ID hybrid model of the electron bombardment in flare loops, we study not only the evolution of densities, plasma velocities and temperatures in the loop, but also the temporal and spatial evolution of hard X-ray emission. In the present paper a continuous bombardment by electrons isotropically accelerated at the top of flare loop with a power-law injection distribution function is considered. The computations include the effects of the return-current that reduces significantly the depth of the chromospheric layer which is evaporated. The present modelling is made with superthermal electron parameters corresponding to the classical resistivity regime for an input energy flux of superthermal electrons of 109erg cm−2s−1. It was found that due to the electron bombardment the two chromospheric evaporation waves are generated at both feet of the loop and they propagate up to the top, where they collide and cause temporary density and hard X-ray enhancements.

Saturn's E, G and F rings: modulated by the plasma sheet

1984 ◽  
Vol 75 ◽  
pp. 597
Author(s):  
E. Grün ◽  
G.E. Morfill ◽  
T.V. Johnson ◽  
G.H. Schwehm
Keyword(s):  
Solar Wind ◽  
Direct Contact ◽  
Transport Processes ◽  
Time Variable ◽  
Dust Particles ◽  
Spatial Diffusion ◽  
Drag Forces ◽  
Orbit Perturbation ◽  
Time Variations ◽  
F Ring

ABSTRACTSaturn's broad E ring, the narrow G ring and the structured and apparently time variable F ring(s), contain many micron and sub-micron sized particles, which make up the “visible” component. These rings (or ring systems) are in direct contact with magnetospheric plasma. Fluctuations in the plasma density and/or mean energy, due to magnetospheric and solar wind processes, may induce stochastic charge variations on the dust particles, which in turn lead to an orbit perturbation and spatial diffusion. It is suggested that the extent of the E ring and the braided, kinky structure of certain portions of the F rings as well as possible time variations are a result of plasma induced electromagnetic perturbations and drag forces. The G ring, in this scenario, requires some form of shepherding and should be akin to the F ring in structure. Sputtering of micron-sized dust particles in the E ring by magnetospheric ions yields lifetimes of 102to 104years. This effect as well as the plasma induced transport processes require an active source for the E ring, probably Enceladus.

Quantitative surface damage studies by H.R.E.M.

1989 ◽  
Vol 47 ◽  
pp. 632-633
Author(s):  
S. R. Singh ◽  
H. J. Fan ◽  
L. D. Marks
Keyword(s):  
Solar Wind ◽  
Quantitative Analysis ◽  
Surface Science ◽  
Surface Damage ◽  
Space Environment ◽  
Oxygen Desorption ◽  
The Past ◽  
Diffusion Controlled ◽  
Original Observation ◽  
Substantial Interest

Since the original observation that the surfaces of materials undergo radiation damage in the electron microscope similar to that observed by more conventional surface science techniques there has been substantial interest in understanding these phenomena in more detail; for a review see. For instance, surface damage in a microscope mimics damage in the space environment due to the solar wind and electron beam lithographic operations.However, purely qualitative experiments that have been done in the past are inadequate. In addition, many experiments performed in conventional microscopes may be inaccurate. What is needed is careful quantitative analysis including comparisons of the behavior in UHV versus that in a conventional microscope. In this paper we will present results of quantitative analysis which clearly demonstrate that the phenomena of importance are diffusion controlled; more detailed presentations of the data have been published elsewhere.As an illustration of the results, Figure 1 shows a plot of the shrinkage of a single, roughly spherical particle of WO3 versus time (dose) driven by oxygen desorption from the surface.

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