The Experts below are selected from a list of 573360 Experts worldwide ranked by ideXlab platform

Shinichiro Oyama - One of the best experts on this subject based on the ideXlab platform.

Yasunobu Ogawa - One of the best experts on this subject based on the ideXlab platform.

Kazushi Asamura - One of the best experts on this subject based on the ideXlab platform.

  • relativistic electron microbursts as high energy tail of pulsating aurora Electrons
    Geophysical Research Letters, 2020
    Co-Authors: S Kurita, Kazushi Asamura, K Hosokawa, Takeshi Sakanoi, Takefumi Mitani, Yasunobu Ogawa, Shinichiro Oyama
    Abstract:

    In this study, by simulating the wave-particle interactions, we show that sub-relativistic/relativistic electron microbursts form the high-energy tail of pulsating aurora (PsA). Whistler-mode choru...

  • time of flight analysis of pulsating aurora Electrons considering wave particle interactions with propagating whistler mode waves
    Journal of Geophysical Research, 2010
    Co-Authors: Yoshizumi Miyoshi, Kazushi Asamura, Takeshi Sakanoi, Yuto Katoh, Takanori Nishiyama, M Hirahara
    Abstract:

    [1] We propose a model for the energy dispersion of electron precipitation associated with pulsating auroras, considering the wave-particle interactions with propagating whistler mode waves from the equator. Since the resonant energy depends on the magnetic latitude, the pitch angle scattering of different energy Electrons can occur continuously along the field line. Considering the energy-dependent path length and the precipitation start time of the precipitating Electrons, the transit time of whistler mode waves, and the frequency drift, we calculated the precipitation of Electrons observed at the topside ionosphere. Note that higher energy Electrons precipitate into the ionosphere of the opposite hemisphere earlier than lower energy Electrons. As a result, an energy dispersion of precipitating Electrons is observed at the topside ionosphere, even though the modulation of low energy Electrons occurs prior to that of high energy Electrons. Using the model, we conducted a time-of-flight (TOF) analysis of precipitating Electrons observed by the REIMEI satellite, assuming an interaction with the whistler mode chorus rising tone. Our TOF analysis suggests that the modulation region of the pitch angle scattering is near the magnetic equator, whereas previous models expected that the modulation region is far from the magnetic equator. The estimated parameters, such as wave-frequency and latitudinal distribution of the modulation region, are consistent with previous statistical studies of whistler waves at the magnetosphere.

Takeshi Sakanoi - One of the best experts on this subject based on the ideXlab platform.

  • relativistic electron microbursts as high energy tail of pulsating aurora Electrons
    Geophysical Research Letters, 2020
    Co-Authors: S Kurita, Kazushi Asamura, K Hosokawa, Takeshi Sakanoi, Takefumi Mitani, Yasunobu Ogawa, Shinichiro Oyama
    Abstract:

    In this study, by simulating the wave-particle interactions, we show that sub-relativistic/relativistic electron microbursts form the high-energy tail of pulsating aurora (PsA). Whistler-mode choru...

  • time of flight analysis of pulsating aurora Electrons considering wave particle interactions with propagating whistler mode waves
    Journal of Geophysical Research, 2010
    Co-Authors: Yoshizumi Miyoshi, Kazushi Asamura, Takeshi Sakanoi, Yuto Katoh, Takanori Nishiyama, M Hirahara
    Abstract:

    [1] We propose a model for the energy dispersion of electron precipitation associated with pulsating auroras, considering the wave-particle interactions with propagating whistler mode waves from the equator. Since the resonant energy depends on the magnetic latitude, the pitch angle scattering of different energy Electrons can occur continuously along the field line. Considering the energy-dependent path length and the precipitation start time of the precipitating Electrons, the transit time of whistler mode waves, and the frequency drift, we calculated the precipitation of Electrons observed at the topside ionosphere. Note that higher energy Electrons precipitate into the ionosphere of the opposite hemisphere earlier than lower energy Electrons. As a result, an energy dispersion of precipitating Electrons is observed at the topside ionosphere, even though the modulation of low energy Electrons occurs prior to that of high energy Electrons. Using the model, we conducted a time-of-flight (TOF) analysis of precipitating Electrons observed by the REIMEI satellite, assuming an interaction with the whistler mode chorus rising tone. Our TOF analysis suggests that the modulation region of the pitch angle scattering is near the magnetic equator, whereas previous models expected that the modulation region is far from the magnetic equator. The estimated parameters, such as wave-frequency and latitudinal distribution of the modulation region, are consistent with previous statistical studies of whistler waves at the magnetosphere.

Ilona Mullerova - One of the best experts on this subject based on the ideXlab platform.

  • collection of secondary Electrons in scanning electron microscopes
    Journal of Microscopy, 2009
    Co-Authors: Ilona Mullerova, Ivo Konvalina
    Abstract:

    Collection of the secondary Electrons in the scanning electron microscope was simulated and the results have been experimentally verified for two types of the objective lens and three detection systems. The aberration coefficients of both objective lenses as well as maximum axial magnetic fields in the specimen region are presented. Compared are a standard side-attached secondary electron detector, in which only weak electrostatic and nearly no magnetic field influence the signal trajectories in the specimen vicinity, and the side-attached (lower) and upper detectors in an immersion system with weak electrostatic but strong magnetic field penetrating towards the specimen. The collection efficiency was calculated for all three detection systems and several working distances. The ability of detectors to attract secondary electron trajectories for various initial azimuthal and polar angles was calculated, too. According to expectations, the lower detector of an immersion system collects no secondary Electrons I and II emitted from the specimen and only backscattered Electrons and secondary Electrons III form the final image. The upper detector of the immersion system exhibits nearly 100% collection efficiency decreasing, however, with the working distance, but the topographical contrast is regrettably suppressed in its image. The collection efficiency of the standard detector is low for short working distances but increases with the same, preserving strong topographical contrast.

  • the trajectories of secondary Electrons in the scanning electron microscope
    Scanning, 2007
    Co-Authors: Ivo Konvalina, Ilona Mullerova
    Abstract:

    : Three-dimensional simulations of the trajectories of secondary Electrons (SE) in the scanning electron microscope have been performed for plenty of real configurations of the specimen chamber, including all its basic components. The primary purpose was to evaluate the collection efficiency of the Everhart-Thornley detector of SE and to reveal fundamental rules for tailoring the set-ups in which efficient signal acquisition can be expected. Intuitive realizations about the easiness of attracting the SEs towards the biased front grid of the detector have shown themselves likely as false, and all grounded objects in the chamber have been proven to influence the spatial distribution of the signal-extracting field. The role of the magnetic field penetrating from inside the objective lens is shown to play an ambiguous role regarding possible support for the signal collection.