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Papers by Masahiro Hoshino

Journal of geomagnetism and geoelectricity, 1993

Scientific Reports, Jun 30, 2022

Physical review research, Apr 27, 2020

Japan Geoscience Union, 2018

Heating and acceleration of magnetospheric plasma have been studied using in-situ plasma and fiel... more Heating and acceleration of magnetospheric plasma have been studied using in-situ plasma and field observations. There are a large number of observation reports that cold and hot plasma coexist in the Earth’s magnetosphere. However, the dominant heating/acceleration mechanisms and regions are not well understood. Moreover, it remains unclear whether the heating/acceleration mechanisms depend on mass. It can help the more understanding of the heating/acceleration mechanism to investigate the hot and cold plasma in the Earth’s magnetosphere. However, only a few satellite missions have been able to observe the thermal component of magnetospheric plasma with mass determination. Therefore, a small number of studies focused on mass-dependent processes in the typical energy range (<1-10 keV) of magnetospheric ions. In this study, we first separated the plasma into hot and cold populations, and then perform statistical analysis for each population. We also perform similar analysis for di...

Nonlinear Processes in Geophysics, 2018

We discuss a non-stochastic particle acceleration mechanism under the cyclotron resonance with tw... more We discuss a non-stochastic particle acceleration mechanism under the cyclotron resonance with two electromagnetic ion-cyclotron (EMIC) waves. We find that the strong ion acceleration occurs in multi-component plasma if a heavy ion can resonate with both the EMIC wave near the cutoff frequency and the other EMIC wave with the Alfven velocity. The particle is preferentially accelerated perpendicular to the

Plasma Physics and Controlled Fusion, 2012

Journal of Plasma Physics, 2016

The Universe is permeated by hot, turbulent, magnetized plasmas. Turbulent plasma is a major cons... more The Universe is permeated by hot, turbulent, magnetized plasmas. Turbulent plasma is a major constituent of active galactic nuclei, supernova remnants, the intergalactic and interstellar medium, the solar corona, the solar wind and the Earth’s magnetosphere, just to mention a few examples. Energy dissipation of turbulent fluctuations plays a key role in plasma heating and energization, yet we still do not understand the underlying physical mechanisms involved. THOR is a mission designed to answer the questions of how turbulent plasma is heated and particles accelerated, how the dissipated energy is partitioned and how dissipation operates in different regimes of turbulence. THOR is a single-spacecraft mission with an orbit tuned to maximize data return from regions in near-Earth space – magnetosheath, shock, foreshock and pristine solar wind – featuring different kinds of turbulence. Here we summarize the THOR proposal submitted on 15 January 2015 to the ‘Call for a Medium-size miss...

Journal of Geophysical Research, Nov 1, 2001

Physical Review Letters, May 7, 2010

Japan Geoscience Union, Mar 14, 2019

AGU Fall Meeting Abstracts, Dec 1, 2009

ABSTRACT It is well known that the plasma sheet becomes cold and dense under prolonged northward ... more ABSTRACT It is well known that the plasma sheet becomes cold and dense under prolonged northward IMF conditions [e.g., Terasawa et al., 1997]. Two major candidates, (1) high latitude reconnections in both hemispheres which capture magnetosheath plasmas on the newly closed field lines (double lobe reconnection) [e.g., Song and Russell, 1992] and (2) effective diffusive transport of magnetosheath plasma induced by the Kelvin-Helmholtz instability at the flank magnetopause [e.g., Hasegawa et al., 2004], have been discussed to account for the formation of the cold dense plasma sheet. The relative importance of the double lobe reconnection and the Kelvin-Helmholtz instability in the formation of the cold dense plasma sheet is so far an open question. We quantitatively examined the properties of the cold dense plasma sheet by fitting the observed ion and electron velocity distributions to a single/two-component Maxwellian. We statistically show that the cold dense plasma sheet in the dusk magnetosphere is characterized by ions consisting of separate cold and hot component and electrons consisting of a single cold component. Although the absence of a hot electron component in the cold dense plasma sheet can be explained naturally if we blame the formation of the cold dense plasma sheet on the double lobe reconnection scenario, it is hard to be explained by diffusion induced by the Kelvin-Helmholtz instability at the magnetopause. We also show that a sharp boundary exists between the cold dense plasma sheet and the hot tenuous plasma sheet. The observed velocity distributions of ions and electrons in the cold dense plasma sheet bordered by the hot tenuous plasma sheet indicate the supply of the hot ion component by diffusion and gradient/curvature B drift. The cold dense plasma sheet observed just inside the Kelvin-Helmholtz unstable magnetopause further suggests that the double lobe reconnection and the Kelvin-Helmholtz instability can occur simultaneously.