A5033227748- Ionosphere and magnetosphere dynamics
- Earthquake Detection and Analysis
- Solar and Space Plasma Dynamics
- Seismic Waves and Analysis
- GNSS positioning and interference
- Astro and Planetary Science
- Geomagnetism and Paleomagnetism Studies
- Geophysics and Gravity Measurements
- Planetary Science and Exploration
- Spacecraft Design and Technology
- Geophysics and Sensor Technology
- Plasma Diagnostics and Applications
- Advanced Frequency and Time Standards
- Magnetic confinement fusion research
- Lightning and Electromagnetic Phenomena
- Space Exploration and Technology
- Atmospheric Ozone and Climate
- Gyrotron and Vacuum Electronics Research
- Spacecraft and Cryogenic Technologies
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Robotics and Sensor-Based Localization
- Diverse Musicological Studies
- Particle accelerators and beam dynamics
- Advanced Data Storage Technologies
NanoDesign (Slovakia)
2023
Japan Aerospace Exploration Agency
2012-2022
Institute of Space and Astronautical Science
2015-2022
Kyoto University
2009-2021
United Nations University Institute for Sustainability and Peace
2021
National Sagamihara Hospital
2017-2020
Nagoya University
2014-2018
Charles University
2018
Tohoku University
2014
Kyoto Bunkyo University
2011
We develop a nonlinear wave growth theory of magnetospheric chorus emissions, taking into account the spatial inhomogeneity static magnetic field and plasma density variation along line. derive theoretical expressions for rate amplitude threshold generation self‐sustaining emissions. assume that whistler mode is initiated at equator where linear maximizes. Self‐sustaining emissions become possible when propagates away from during which process increasing gradients electron provide conditions...
The Exploration of energization and Radiation in Geospace (ERG) project aims to study acceleration loss mechanisms relativistic electrons around the Earth. Arase satellite was launched on December 20, 2016, explore heart Earth's radiation belt. In present paper, we introduce specifications Plasma Wave Experiment (PWE) board satellite. inner magnetosphere, plasma waves, such as whistler-mode chorus, electromagnetic ion cyclotron wave, magnetosonic are expected interact with particles over a...
Abstract We perform test particle simulations of energetic electrons interacting with whistler mode chorus emissions. compute trajectories a large number forming delta function the same energy and equatorial pitch angle. The are launched at different locations along magnetic field line timings respect to pair emissions generated equator. follow evolution obtain distribution in angle, which is numerical Green's for one cycle wave‐particle interaction. functions range 10 keV–6 MeV all angles...
We developed the onboard processing software for Plasma Wave Experiment (PWE) Exploration of energization and Radiation in Geospace, Arase satellite. The PWE instrument has three receivers: Electric Field Detector, Waveform Capture/Onboard Frequency Analyzer (WFC/OFA), High-Frequency Analyzer. designed a pseudo-parallel scheme with time-sharing system achieved simultaneous signal each receiver. Since electric magnetic field signals are processed by different CPUs, we synchronized observation...
We perform an electromagnetic full particle simulation to study the generation mechanism of VLF whistler‐mode chorus emissions in equatorial region magnetosphere. Parabolic variation static magnetic field is assumed as a model for dipole vicinity equator. have cold thermal electrons and relatively low anisotropic hot plasma particles. In initial phase, amplitude growth incoherent waves determined by linear rate. When wave reaches certain level, it begins grow more rapidly with series rising...
Electron microbursts, which are short‐duration (<1 sec) bursts of energetic electrons that precipitate into the Earth's atmosphere, comprise an important loss process from outer radiation belt. By means a self‐consistent full‐particle simulation, we show microburst precipitation energies 10 keV–100 keV accompanies generation discrete bursty chorus wave emissions. Specifically, demonstrate one‐to‐one correspondence between electron microbursts and elements. This simulation study is first...
Abstract Recent observations of plasmaspheric hiss emissions by the Van Allen Probes show that broadband in plasmasphere comprise short‐time coherent elements with rising and falling tone frequencies. Based on nonlinear wave growth theory whistler mode chorus emissions, we have examined applicability to emissions. We generalized derivation optimum amplitude for triggering cases both elements. The profiles are well approximated amplitudes or tones. Through formation electron holes tones hills...
Abstract Pulsating auroras (PsAs) are thought to be generated by precipitating electrons scattered lower‐band chorus (LBC) waves near the magnetic equator. One‐to‐one correlation between LBC intensity and PsA has been reported. Electrostatic electron cyclotron harmonic (ECH) can also scatter electrons. However, direct ECH not reported yet. In this study, using a coordinated Exploration of energization Radiation in Geospace (Arase) satellite ground‐based imager observation, we report that...
Chorus waves, among the most intense electromagnetic emissions in Earth's magnetosphere, magnetized planets, and laboratory plasmas, play an important role acceleration loss of energetic electrons plasma universe through resonant interactions with electrons. However, spatial evolution electron waves remains poorly understood owing to imaging difficulties. Here we provide a compelling visualization chorus element wave-particle magnetosphere. Through in-situ measurements waveforms Arase...
We perform self‐consistent electromagnetic particle simulations to analyze whistler‐mode triggered emissions in the magnetosphere. The triggering waves with different wave amplitudes and a constant frequency are injected at equator. With greater than threshold for nonlinear growth, rising‐tone successfully excited near detailed time evolutions of frequencies show similar development. A recent theoretical study found optimum amplitude emissions. condition is confirmed by simulations. an much...
Abstract Rapid (<1 s) intensity modulation of pulsating auroras is caused by successive chorus elements as a response to wave‐particle interactions in the magnetosphere. Here we found that auroral patch responds time spacing for and possibly subpacket structures with scale tens milliseconds. These responses were identified from coordinated Arase satellite ground (Gakona, Alaska) observations high‐speed imager (100 Hz). The temporal variations few‐hertz frequency range exhibited spatial...
Abstract Whistler mode chorus waves have recently been established as the most likely candidate for scattering relativistic electrons to produce electron microbursts observed by low altitude satellites and balloons. These would propagate from equatorial source region significantly higher magnetic latitude in order scatter of these energies. This theoretically proposed propagation has never directly observed. We present first direct observations same discrete rising tone elements propagating...
Self‐consistent electromagnetic particle simulations were performed to analyze whistler mode triggered emissions in the magnetosphere. Triggering waves injected at magnetic equator induces a nonlinear absolute instability that results rising tone similar natural chorus emissions. The triggering wave causes depletion of resonant electrons resonance velocity. phase‐organized released by generate coherent undergo growth with increasing frequencies. essential mechanism is same as for generation...
Abstract Chorus waves are a kind of intense electromagnetic emission wave in magnetized planets and can play important roles the kinetic electron dynamics planetary magnetospheres. Rapid changes ring current belt Mercury’s magnetosphere contribution chorus have remained long‐standing scientific issues from first Mercury flyby observations by Mariner 10 1970s because small size magnetosphere. Based on theoretical analyses simulations successfully reconstructing Earth’s properties, we report...
We describe the principles of Wave–Particle Interaction Analyzer (WPIA) and implementation Software-type WPIA (S-WPIA) on Arase satellite. The is a new type instrument for direct quantitative measurement wave–particle interactions. S-WPIA installed satellite as software function running mission data processor. board uses an electromagnetic field waveform that measured by capture receiver plasma wave experiment (PWE), velocity vectors electrons detected medium-energy particle...
Cyclotron resonant wave‐particle interaction of whistler mode chorus emissions drives pitch angle scatterings a wide range energetic electrons in the magnetosphere. We study coherent scattering process associated with generation rising near geomagnetic equator self‐consistent electromagnetic full‐particle simulation. The simulation shows that scatter very effectively through formation an electron hole. nonlinear induces acceleration trapped by wave and deceleration untrapped electrons. When...
Abstract Nonlinear gyroresonant acceleration is an essential mechanism for the formation of relativistic electrons in Earth's radiation belts, yet we still have only limited knowledge how electron motion interacts nonlinearly with plasma waves. Here demonstrate compelling suppression whistler‐mode chorus emissions as a resonant wave energetic by tuning external transmitter signal space plasmas. Through forcible modification motions via phase trapping waves, nonlinear current suppressed along...
The software-type wave–particle interaction analyzer (S-WPIA) is an instrument package onboard the Arase satellite, which studies magnetosphere. S-WPIA represents a new method for directly observing interactions spacecraft in space plasma environment. main objective of to quantitatively detect associated with whistler-mode chorus emissions and electrons over wide energy range (from several keV MeV). quantity exchanges between waves particles can be represented as inner product wave...
Abstract Using the plasma wave and electron data obtained from Time History of Events Macroscale Interactions during Substorms, we show a signature pitch angle scattering driven by Electrostatic Cyclotron Harmonic (ECH) waves in velocity distribution function (VDF). The diffusion curve whistler mode is used as proxy to identify changes VDFs due wave‐particle interactions. We confirm that shape VDF well agrees with when chorus alone active. On other hand, find deviates curves at low angles...
Arase is a small scientific satellite program conducted by the Institute of Space and Astronautical Science/Japan Aerospace Exploration Agency, which dedicated to detailed study radiation belts around Earth through in situ observations. In particular, goal directly observe interaction between plasma waves particles, cause generation high-energy electrons. To particles detail, we must record large volumes burst data with high transmission rates onboard mission network systems. For this...
Abstract We present the first and direct comparison between magnetospheric plasma waves polar mesosphere winter echoes (PMWE) simultaneously observed by conjugate observation with Arase satellite high‐power atmospheric radars in both hemispheres, namely, Program of Antarctic Syowa Mesosphere, Stratosphere, Troposphere/Incoherent Scatter Radar at Station (SYO; −69.00°S, 39.58°E), Antarctica, Middle Atmosphere Alomar System Andøya (AND; 69.30°N, 16.04°E), Norway. The PMWE were during 03–07 UT...
Abstract We have conducted a one‐dimensional electromagnetic particle simulation with parabolic magnetic field to reproduce whistler‐mode hiss emissions in the plasmasphere. assume bi‐Maxwellian distribution temperature anisotropy for energetic electrons injected into plasmasphere and find that are generated spectrum characteristics typical of those observed by spacecraft near equator. The contain fine structures involving rising tone falling elements variation frequencies. amplitude profile...