scholarly journals Energy transfer from lower energy to higher‐energy electrons mediated by whistler waves in the radiation belts

2017 ◽  
Vol 122 (1) ◽  
pp. 640-655 ◽  
Author(s):  
D. R. Shklyar
Keyword(s):  
Energy Transfer ◽  
Lower Energy ◽  
Radiation Belts ◽  
Whistler Waves

scholarly journals Ultrafast wave-particle energy transfer in the collapse of standing whistler waves

2019 ◽  
Vol 100 (5) ◽  
Author(s):  
Takayoshi Sano ◽  
Masayasu Hata ◽  
Daiki Kawahito ◽  
Kunioki Mima ◽  
Yasuhiko Sentoku
Keyword(s):  
Energy Transfer ◽  
Particle Energy ◽  
Whistler Waves

Improved wear properties of high energy ion-implanted polycarbonate

1995 ◽  
Vol 10 (1) ◽  
pp. 190-201 ◽  
Author(s):  
G.R. Rao ◽  
E.H. Lee ◽  
R. Bhattacharya ◽  
A.W. McCormick
Keyword(s):  
Energy Transfer ◽  
Lower Energy ◽  
Sliding Wear ◽  
Ion Irradiation ◽  
Surface Hardness ◽  
High Energy ◽  
Cross Linking ◽  
Wear Properties ◽  
Hardness Values ◽  
Wear Tests

Polycarbonate (LexanTM) (PC) was implanted with 2 MeV B+ and O+ ions separately to fluences of 5 × 1017, 1 × 1018, and 5 × 1018 ions/m2, and characterized for changes in surface hardness and tribological properties. Results of tests showed that hardness values of all implanted specimens increased over those of the unirradiated material, and the O+ implantation was more effective in improving hardness for a given fluence than the B+ implantation. Reciprocating sliding wear tests using a nylon ball counterface yielded significant improvements for all implanted specimens except for the 5 × 1017 ions/m2 B+-implanted PC. Wear tests conducted with a 52100 steel ball yielded significant improvements for the highest fluence of 5 × 1018 ions/m2 for both ions, but not for the two lower fluences. The improvements in properties were related to Linear Energy Transfer (LET) mechanisms, where it was shown that the O+ implantation caused greater ionization, thereby greater cross-linking at the surface corresponding to much better improvements in properties. The results were also compared with a previous study on PC using 200 keV B+ ions. The present study indicates that high energy ion irradiation produces thicker, more cross-linked, harder, and more wear-resistant surfaces on polymers and thereby improves properties to a greater extent and more efficiently than lower energy ion implantation.

scholarly journals Mechanisms Affecting Emission in Rare-Earth-Activated Phosphors

2000 ◽  
Vol 621 ◽  
Author(s):  
David R. Tallant ◽  
Carleton H. Seager ◽  
Regina L. Simpson
Keyword(s):  
Energy Transfer ◽  
Rare Earth ◽  
Lower Energy ◽  
Electron Beams ◽  
Low Energy ◽  
Flat Panel Displays ◽  
Relaxation Model ◽  
Activator Concentration ◽  
Flat Panel ◽  
Low Energy Electron

ABSTRACTThe relatively poor efficiency of phosphor materials in cathodoluminescence with low accelerating voltages is a major concern in the design of field emission flat panel displays operated below 5 kV. Our research on rare-earth-activated phosphors indicates that mechanisms involving interactions of excited activators have a significant impact on phosphor efficiency. Persistence measurements in photoluminescence (PL) and cathodoluminescence (CL) show significant deviations from the sequential relaxation model. This model assumes that higher excited manifolds in an activator de-excite primarily by phonon-mediated sequential relaxation to lower energy manifolds in the same activator ion. In addition to sequential relaxation, there appears to be strong coupling between activators, which results in energy transfer interactions. Some of these interactions negatively impact phosphor efficiency by nonradiatively de-exciting activators. Increasing activator concentration enhances these interactions. The net effect is a significant degradation in phosphor efficiency at useful activator concentrations, which is exaggerated when low–energy electron beams are used to excite the emission.

Electron Acceleration in the Heart of the Van Allen Radiation Belts

Science ◽  
2013 ◽  
Vol 341 (6149) ◽  
pp. 991-994 ◽  
Author(s):  
G. D. Reeves ◽  
H. E. Spence ◽  
M. G. Henderson ◽  
S. K. Morley ◽  
R. H. W. Friedel ◽  
...  
Keyword(s):  
Lower Energy ◽  
Radiation Belt ◽  
Radiation Belts ◽  
Source Population ◽  
Acceleration Process ◽  
Radial Acceleration ◽  
High Energies ◽  
Radial Profiles ◽  
Radiation Belt Storm Probes

The Van Allen radiation belts contain ultrarelativistic electrons trapped in Earth’s magnetic field. Since their discovery in 1958, a fundamental unanswered question has been how electrons can be accelerated to such high energies. Two classes of processes have been proposed: transport and acceleration of electrons from a source population located outside the radiation belts (radial acceleration) or acceleration of lower-energy electrons to relativistic energies in situ in the heart of the radiation belts (local acceleration). We report measurements from NASA’s Van Allen Radiation Belt Storm Probes that clearly distinguish between the two types of acceleration. The observed radial profiles of phase space density are characteristic of local acceleration in the heart of the radiation belts and are inconsistent with a predominantly radial acceleration process.

Nonlinear evolution of oblique whistler waves in radiation belts

2017 ◽  
Vol 362 (2) ◽  
Author(s):  
R. P. Sharma ◽  
P. Nandal ◽  
N. Yadav ◽  
Swati Sharma
Keyword(s):  
Nonlinear Evolution ◽  
Radiation Belts ◽  
Whistler Waves

Upward propagation of lightning-generated whistler waves into the radiation belts

2019 ◽  
Vol 63 (2) ◽  
pp. 243-248
Author(s):  
MingYue Guo ◽  
QingHua Zhou ◽  
FuLiang Xiao ◽  
Si Liu ◽  
YiHua He ◽  
...  
Keyword(s):  
Radiation Belts ◽  
Whistler Waves

A quantitative approach to inner shell losses

1978 ◽  
Vol 36 (1) ◽  
pp. 526-527 ◽  
Author(s):  
R.D. Leapman ◽  
P. Rez ◽  
D.F. Mayers
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Determination ◽  
Background Intensity ◽  
Core Excitation ◽  
Quantitative Basis ◽  
Cross Section Differential ◽  
Bound Electrons

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as

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