scholarly journals Impact of Foreshock Transients on the Flank Magnetopause and Magnetosphere and the Ionosphere

2021 ◽  
Vol 8 ◽  
Author(s):  
Chih-Ping Wang ◽  
Xueyi Wang ◽  
Terry Z. Liu ◽  
Yu Lin
Keyword(s):  
Magnetic Field ◽  
3D Structure ◽  
Hybrid Simulation ◽  
High Density ◽  
Low Density ◽  
Simulation Results ◽  
Ground Magnetic ◽  
Pressure Perturbations

Mesoscale (on the scales of a few minutes and a few RE) magnetosheath and magnetopause perturbations driven by foreshock transients have been observed in the flank magnetotail. In this paper, we present the 3D global hybrid simulation results to show qualitatively the 3D structure of the flank magnetopause distortion caused by foreshock transients and its impacts on the tail magnetosphere and the ionosphere. Foreshock transient perturbations consist of a low-density core and high-density edge(s), thus, after they propagate into the magnetosheath, they result in magnetosheath pressure perturbations that distort magnetopause. The magnetopause is distorted locally outward (inward) in response to the dip (peak) of the magnetosheath pressure perturbations. As the magnetosheath perturbations propagate tailward, they continue to distort the flank magnetopause. This qualitative explains the transient appearance of the magnetosphere observed in the flank magnetosheath associated with foreshock transients. The 3D structure of the magnetosheath perturbations and the shape of the distorted magnetopause keep evolving as they propagate tailward. The transient distortion of the magnetopause generates compressional magnetic field perturbations within the magnetosphere. The magnetopause distortion also alters currents around the magnetopause, generating field-aligned currents (FACs) flowing in and out of the ionosphere. As the magnetopause distortion propagates tailward, it results in localized enhancements of FACs in the ionosphere that propagate anti-sunward. This qualitatively explains the observed anti-sunward propagation of the ground magnetic field perturbations associated with foreshock transients.

scholarly journals Electric fields and double layers in plasmas

1987 ◽  
Vol 5 (2) ◽  
pp. 233-255 ◽  
Author(s):  
Nagendra Singh ◽  
H. Thiemann ◽  
R. W. Schunk
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Electric Fields ◽  
Sheet Thickness ◽  
High Density ◽  
Effective Length ◽  
Double Layers ◽  
Low Density ◽  
Ambient Magnetic Field ◽  
Cold Plasmas

Various mechanisms for driving double layers in plasmas are briefly described, including applied potential drops, currents, contact potentials, and plasma expansions. Some dynamic features of the double layers are discussed. These features, as seen in simulations, laboratory experiments and theory, indicate that double layers and the currents through them undergo slow oscillations, which are determined by the ion transit time across an effective length of the system in which the double layers form. It is shown that a localized potential dip forms at the low potential end of a double layer, which interrupts the electron current through it according to the Langmuir criterion, whenever the ion flux into the double is disrupted. The generation of electric fields perpendicular to the ambient magnetic field by contact potentials is also discussed. Two different situations have been considered; in one, a low-density hot plasma is sandwiched between high-density cold plasmas, while in the other a high-density current sheet permeates a low-density background plasma. Perpendicular electric fields develop near the contact surfaces. In the case of the current sheet, the creation of parallel electric fields and the formation of double layers are also discussed when the current sheet thickness is varied. Finally, the generation of electric fields (parallel to an ambient magnetic field) and double layers in an expanding plasma are discussed.

Analyzing the Effect of Node Density on the Performance of the LAR-1P Algorithm

2012 ◽  
Vol 7 (2) ◽  
pp. 16-29
Author(s):  
Hussein Al-Bahadili ◽  
Ali Maqousi ◽  
Reyadh S. Naoum
Keyword(s):  
Network Performance ◽  
Ad Hoc ◽  
High Density ◽  
Low Density ◽  
Probabilistic Algorithms ◽  
Excellent Performance ◽  
Node Density ◽  
Simulation Results ◽  
Mobile Ad Hoc ◽  
Hoc Networks

The location-aided routing scheme 1 (LAR-1) and probabilistic algorithms are combined together into a new algorithm for route discovery in mobile ad hoc networks (MANETs) called LAR-1P. Simulation results demonstrated that the LAR-1P algorithm reduces the number of retransmissions as compared to LAR-1 without sacrificing network reachability. Furthermore, on a sub-network (zone) scale, the algorithm provides an excellent performance in high-density zones, while in low-density zones; it preserves the performance of LAR-1. This paper provides a detailed analysis of the performance of the LAR-1P algorithm through various simulations, where the actual numerical values for the number of retransmissions and reachability in high- and low-density zones were computed to demonstrate the effectiveness and significance of the algorithm and how it provides better performance than LAR-1 in high-density zones. In addition, the effect of the total number of nodes on the average network performance is also investigated.

Mercury’s magnetosphere–solar wind interaction for northward and southward interplanetary magnetic field: Hybrid simulation results

Icarus ◽  
2010 ◽  
Vol 209 (1) ◽  
pp. 11-22 ◽  
Author(s):  
Pavel M. Trávníček ◽  
David Schriver ◽  
Petr Hellinger ◽  
David Herčík ◽  
Brian J. Anderson ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Interplanetary Magnetic Field ◽  
Hybrid Simulation ◽  
Solar Wind Interaction ◽  
Simulation Results

scholarly journals Polyamorphism and Two State Model in Liquid GeO\(_{2}\) under Compression: Insight from Visualization of Molecular Dynamics Data

2014 ◽  
Vol 24 (3S1) ◽  
pp. 95-98
Author(s):  
Nguyen Van Hong ◽  
Mai Thi Lan ◽  
Nguyen Thu Nhan
Keyword(s):  
Molecular Dynamics ◽  
Phase Region ◽  
High Density ◽  
State Model ◽  
Dynamics Simulation ◽  
Low Density ◽  
Wide Pressure Range ◽  
Simulation Results ◽  
Two State Model ◽  
Wide Pressure

The polyamorphism and two-state model based on the coordination number distribution in liquid GeO\(_{2}\) at 3200~K and in a wide pressure range are investigated by molecular dynamics simulation. Results show that the structure of liquid GeO\(_{2}\) mainly consists of GeO\(_{x}\) coordination units \((x=4,5,6)\) and OGe\(_{y}\) linkages \((y=2, 3)\). The distribution of OGe\(_{y}\) linkages in network structure is not uniform but tends to form clusters of OGe\(_{y}\). The cluster of OGe\(_{2}\) will form low-density phase region, conversely the cluster of OGe\(_{3}\) will form high-density phase region. In other word, under compression, in the liquid GeO\(_{2}\) coexist two states: low-density and high-density. The size of phase regions significantly depends on compression.

Quantitative defect studies in semiconductor TEM samples prepared by low angle ion milling

1995 ◽  
Vol 53 ◽  
pp. 512-513
Author(s):  
L. Mulestagno ◽  
J.C. Holzer ◽  
P. Fraundorf
Keyword(s):  
Sample Preparation ◽  
Milling Time ◽  
High Density ◽  
Low Density ◽  
Ion Milling ◽  
High Quality ◽  
Variable Angle ◽  
Major Disadvantage ◽  
Induced Defects

Due to the wealth of information, both analytical and structural that can be obtained from it TEM always has been a favorite tool for the analysis of process-induced defects in semiconductor wafers. The only major disadvantage has always been, that the volume under study in the TEM is relatively small, making it difficult to locate low density defects, and sample preparation is a somewhat lengthy procedure. This problem has been somewhat alleviated by the availability of efficient low angle milling.Using a PIPS® variable angle ion -mill, manufactured by Gatan, we have been consistently obtaining planar specimens with a high quality thin area in excess of 5 × 104 μm2 in about half an hour (milling time), which has made it possible to locate defects at lower densities, or, for defects of relatively high density, obtain information which is statistically more significant (table 1).

Scanning Electron Microscopic and Electrophoretic Observations on Barium Sulphate Used to Adsorb Clotting Factors

1975 ◽  
Vol 33 (02) ◽  
pp. 256-270
Author(s):  
R. M Howell ◽  
S. L. M Deacon
Keyword(s):  
Electron Microscopy ◽  
Factor Xa ◽  
Barium Sulphate ◽  
High Density ◽  
Low Density ◽  
Factor X ◽  
Clotting Factors ◽  
Electron Microscopic ◽  
Complementary Techniques ◽  
Scanning Electron

SummaryElectron microscopy and particle electrophoresis were found to be complementary techniques with which to complete the physical data from an earlier study on barium sulphates used to adsorb clotting factors from serum. The differences revealed by scanning electron microscopy (S. E. M.) in the physical shape of low and high density grades of barium sulphate particles appear to be of greater significance than charge as expressed by electrophoretic mobility, in determining whether or not precursor or preformed factor Xa is eluted.This conclusion was based on the finding that at pH values close to 7, where the adsorption from serum occurs, all samples with the exception of natural barytes were uncharged. However as the high-density, or soil-grade, was found by S. E. M. to consist of large solid crystals it was suggested that this shape might induce activation of factor X as a result of partial denaturation and consequent unfolding of the adsorbed protein. In contrast, uptake of protein into the centre of the porous aggregates revealed by S. E. M. pictures of low-density or X-ray grade barium sulphate may afford protection against denaturation and exposure of the enzyme site.The porous nature of particles of low-density barium sulphate compared with the solid crystalline forms of other grades accounts not only for its lower bulk density but also for its greater surface/gram ratio which is reflected by an ability to adsorb more protein from serum.Neither technique produced evidence from any of the samples to indicate the presence of stabilising agents sometimes used to coat particles in barium meals.

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