Upper limit on the inner radiation belt MeV electron intensity

Recent analysis of energetic electron measurements from the Magnetic Electron Ion Spectrometer instruments onboard the Van Allen Probes showed a local time variation of the equatorial electron intensity in the Earth’s inner radiation belt. The local time asymmetry was interpreted as evidence of drift shell distortion by a large-scale electric field. It was also demonstrated that the inclusion of a simple dawn-to-dusk electric field model improved the agreement between observations and theoretical expectations. Yet, exactly what drives this electric field was left unexplained. We combine in-situ field and particle observations, together with a physics-based coupled model, the Rice Convection Model (RCM) Coupled Thermosphere-Ionosphere-Plasmasphere-electrodynamics (CTIPe), to revisit the local time asymmetry of the equatorial electron intensity observed in the innermost radiation belt. The study is based on the dawn-dusk difference in equatorial electron intensity measured at L = 1.30 during the first 60 days of the year 2014. Analysis of measured equatorial electron intensity in the 150–400 keV energy range, in-situ DC electric field measurements and wind dynamo modeling outputs provide consistent estimates of the order of 6–8 kV for the average dawn-to-dusk electric potential variation. This suggests that the dynamo electric fields produced by tidal motion of upper atmospheric winds flowing across Earth’s magnetic field lines - the quiet time ionospheric wind dynamo - are the main drivers of the drift shell distortion in the Earth’s inner radiation belt.

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The multiple scattering of 4.5 MeV electrons

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1956.0019 ◽

1956 ◽

Vol 234 (1196) ◽

pp. 116-124 ◽

Cited By ~ 1

Keyword(s):

Multiple Scattering ◽

Photographic Method ◽

Scattered Electron ◽

Upper Limit ◽

Aluminium Copper ◽

Electron Intensity ◽

Good Agreement

The multiple scattering of 4.5 MeV electrons by foils of aluminium, copper, molybdenum, silver and platinum has been determined, using a photographic method to measure the variation of scattered electron intensity with angle. It was found that the results were in good agreement with the Moliere theory into the region of plural scattering, this being the upper limit of angles covered by the observations.

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Venus: An Upper Limit on Intrinsic Magnetic Dipole Moment Based on Absence of a Radiation Belt

Science ◽

10.1126/science.158.3809.1673 ◽

1967 ◽

Vol 158 (3809) ◽

pp. 1673-1675 ◽

Cited By ~ 15

Author(s):

J. A. Van Allen ◽

S. M. Krimgis ◽

L. A. Frank ◽

T. P. Armstrong

Keyword(s):

Dipole Moment ◽

Magnetic Dipole ◽

Magnetic Dipole Moment ◽

Radiation Belt ◽

Upper Limit

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Thickness and composition determinations from T.E.M. specimens using both x-ray and backscattered electron data

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100112816 ◽

1984 ◽

Vol 42 ◽

pp. 576-577

Author(s):

M.D. Ball ◽

H. Lagace ◽

M.C. Thornton

Keyword(s):

Electron Microscope ◽

Atomic Number ◽

Transmission Electron Microscope ◽

Convenient Method ◽

Flow Chart ◽

X Ray ◽

Intensity Measurements ◽

Transmission Electron ◽

Electron Intensity ◽

Backscattered Electron

The backscattered electron coefficient η for transmission electron microscope specimens depends on both the atomic number Z and the thickness t. Hence for specimens of known atomic number, the thickness can be determined from backscattered electron coefficient measurements. This work describes a simple and convenient method of estimating the thickness and the corrected composition of areas of uncertain atomic number by combining x-ray microanalysis and backscattered electron intensity measurements.The method is best described in terms of the flow chart shown In Figure 1. Having selected a feature of interest, x-ray microanalysis data is recorded and used to estimate the composition. At this stage thickness corrections for absorption and fluorescence are not performed.

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Local thickness determination by Electron Energy Loss Spectroscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100172450 ◽

1994 ◽

Vol 52 ◽

pp. 944-945

Author(s):

Suichu Luo ◽

John R. Dunlap ◽

Richard W. Williams ◽

David C. Joy

Keyword(s):

Energy Loss ◽

Analytical Electron Microscopy ◽

Mean Free Path ◽

Single Scattering ◽

Specimen Thickness ◽

Three Dimension ◽

Angular Correction ◽

Electron Intensity ◽

Image Position ◽

Inelastic Mean Free Path

In analytical electron microscopy, it is often important to know the local thickness of a sample. The conventional method used for measuring specimen thickness by EELS is:where t is the specimen thickness, λi is the total inelastic mean free path, IT is the total intensity in an EEL spectrum, and I0 is the zero loss peak intensity. This is rigorouslycorrect only if the electrons are collected over all scattering angles and all energy losses. However, in most experiments only a fraction of the scattered electrons are collected due to a limited collection semi-angle. To overcome this problem we present a method based on three-dimension Poisson statistics, which takes into account both the inelastic and elastic mixed angular correction.The three-dimension Poisson formula is given by:where I is the unscattered electron intensity; t is the sample thickness; λi and λe are the inelastic and elastic scattering mean free paths; Si (θ) and Se(θ) are normalized single inelastic and elastic angular scattering distributions respectively ; F(E) is the single scattering normalized energy loss distribution; D(E,θ) is the plural scattering distribution,

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Quantitative Electron Microscope with imaging plate

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100169778 ◽

1994 ◽

Vol 52 ◽

pp. 408-409

Author(s):

D. Shindo

Keyword(s):

Electron Microscope ◽

Dynamic Range ◽

Processing System ◽

Digital Data ◽

Imaging Plate ◽

Crystal Thickness ◽

X Ray Diffraction ◽

Resolution Electron ◽

Electron Intensity ◽

Diffraction Patterns

Imaging plate has good properties, i.e., a wide dynamic range and good linearity for the electron intensity. Thus the digital data (2048x1536 pixels, 4096 gray levels in log scale) obtained with the imaging plate can be used for quantification in electron microscopy. By using the image processing system (PIXsysTEM) combined with a main frame (ACOS3900), quantitative analysis of electron diffraction patterns and high-resolution electron microscope (HREM) images has been successfully carried out.In the analysis of HREM images observed with the imaging plate, quantitative comparison between observed intensity and calculated intensity can be carried out by taking into account the experimental parameters such as crystal thickness and defocus value. An example of HREM images of quenched Tl2Ba2Cu1Oy (Tc = 70K) observed with the imaging plate is shown in Figs. 1(b) - (d) comparing with a structure model proposed by x-ray diffraction study of Fig. 1 (a). The image was observed with a JEM-4000EX electron microscope (Cs =1.0 mm).

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