scholarly journals Hybrid simulations of EMIC waves in a dipolar magnetic field

2011 ◽  
Vol 116 (A9) ◽  
pp. n/a-n/a ◽  
Author(s):  
N. Omidi ◽  
R. Thorne ◽  
J. Bortnik
Keyword(s):  
Magnetic Field ◽  
Emic Waves ◽  
Hybrid Simulations

Plasma instabilities driven by pickup ions of ring-beam velocity distributions in the outer heliosheath 

2021 ◽  
Author(s):  
Ameneh Mousavi ◽  
Kaijun Liu ◽  
Sina Sadeghzadeh
Keyword(s):  
Magnetic Field ◽  
Maximum Growth ◽  
Dispersion Analysis ◽  
Maximum Growth Rate ◽  
Injection Velocity ◽  
Plasma Instabilities ◽  
Pickup Ions ◽  
Beam Velocity ◽  
Background Magnetic Field ◽  
Hybrid Simulations

<p><span>The stability of the pickup ions in the outer heliosheath has been studied by many researchers because of its relevance to the energetic neutral atom (ENA) ribbon observed by the Interstellar Boundary EXplorer. However, previous studies are primarily limited to pickup ions of near </span><span>90° </span><span>pickup angles, the angle between the pickup ion injection velocity and the background, local interstellar magnetic field. Investigations on pickup ions of smaller pickup angles are still lacking. In this paper, linear kinetic dispersion analysis and hybrid simulations are carried out to examine the plasma instabilities driven by pickup ions of ring-beam velocity distributions at various pickup angles between zero and </span><span>90°</span><span>. </span><span>Parallel propagating waves are studied in the parameter regime where the parallel thermal spread of the pickup ions falls into the Alfvén cyclotron stability gap. </span><span>The linear analysis results and hybrid simulations both show that the fastest growing modes are the right-hand helicity waves propagating in the direction of the background magnetic field, and the maximum growth rate occurs at the pickup angle of </span><span>82°</span><span>. The simulation results further reveal that the saturation level of the fluctuating magnetic fields for pickup angles below </span><span>45° </span><span>is higher than that for pickup angles above </span><span>45°</span><span>. So, the scattering of pickup ions at near zero pickup angles is likely more pronounced than that at near </span><span>90° </span><span>pickup angles</span> .</p>

Feasibility study of an adaptive mount system based on magnetorheological elastomer using real-time hybrid simulation

2018 ◽  
Vol 30 (5) ◽  
pp. 701-707 ◽  
Author(s):  
Seung-Hyun Eem ◽  
Jeong-Hoi Koo ◽  
Hyung-Jo Jung
Keyword(s):  
Magnetic Field ◽  
Control System ◽  
Real Time ◽  
Control Algorithm ◽  
Vibration Reduction ◽  
Hybrid Simulation ◽  
Shaking Table ◽  
Magnetorheological Elastomer ◽  
Experimental Part ◽  
Hybrid Simulations

This article investigates an adaptive mount system based on magnetorheological elastomer in reducing the vibration of an equipment on the isolation table. Incorporating MR elastomers, whose elastic modulus or stiffness can be adjusted depending on the applied magnetic field, the proposed mount system strives to alleviate the limitations of existing passive-type mount systems. The primary goal of this study is to evaluate the vibration reduction performance of the proposed MR elastomer mount using the hybrid simulation technique. For real-time hybrid simulations, the MR elastomer mount and the control system are used as an experimental part, which is installed on the shaking table, and an equipment on the table is used as a numerical part. A suitable control algorithm is designed for the real-time hybrid simulations to avoid the responses of the equipment’s natural frequency by tracking the frequencies of the responses. After performing a series of real-time hybrid simulation on the adaptive mount system and the passive-type mount system under sinusoidal excitations, this study compares the effectiveness of the adaptive mount system over its passive counterpart. The results show that the proposed adaptive elastomer mount system outperforms the passive-type mount system in reducing the responses of the equipment for the excitations considered in this study.

Observations of simultaneously occurring ULF and Ion Cyclotron Waves by the GOES-16 satellite magnetometer and particle detectors at geostationary orbit

2020 ◽  
Author(s):  
Paul Loto'aniu
Keyword(s):  
Magnetic Field ◽  
Ring Current ◽  
Resonance Condition ◽  
Sampling Rate ◽  
Ion Fluxes ◽  
Ulf Waves ◽  
Ulf Wave ◽  
Ion Cyclotron ◽  
Generation Mechanisms ◽  
Emic Waves

<p>The GOES-16 spacecraft, launched in November 2016, is the first of the GOES-R series next generation NOAA weather satellites. The spacecraft has a similar suite of space weather instruments to previous GOES satellites but with improved magnetometer sampling rate and wider energy range of particle flux observations. Presented are observations of simultaneously occurring Pc 4/5 ULF waves and electromagnetic ion cyclotron (EMIC) waves with a discussion on the relationship between the two wave modes including possible generation mechanisms. The waves were also observed in the particle data and we discuss both adiabatic and non-adiabatic wave-particle effects. Relativistic electron fluxes showed strong adiabatic motion with the magnetic field ULF waves. Estimates of Pc 4/5 ULF wave m-numbers suggest they were high, while ring current energy ion fluxes showed ULF variations with non-zero phasing relative to magnetic field ULF wave. This suggests ULF wave drift resonance with ring current ions. In one event we observed EMIC variations in the ion fluxes around energies that can drift resonate with simultaneously observed Pc 5 waves, suggesting that one particle population may be responsible for generating and/or modifying both observed Pc 5 and EMIC waves. ULF variations were also observed in electron/ion fluxes at lower energies down to 30 eV. We looked into ULF bounce resonance with 30 eV electrons, but the resonance condition did not match the observations. We will also discuss future plans to expand this study of ULF waves and wave-particle interactions using the two newest GOES satellites.</p>

A case study of EMIC waves associated with sudden geosynchronous magnetic field changes

2017 ◽  
Vol 122 (3) ◽  
pp. 3322-3341 ◽  
Author(s):  
Khan‐Hyuk Kim ◽  
Yoshiharu Omura ◽  
Ho Jin ◽  
Junga Hwang
Keyword(s):  
Magnetic Field ◽  
Emic Waves

scholarly journals Ionospheric Pc1 waves during a storm recovery phase observed by CSES

2020 ◽  
Author(s):  
Xiaochen Gou ◽  
Lei Li ◽  
Yiteng Zhang ◽  
Bin Zhou ◽  
Yongyong Feng ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Storms ◽  
Recovery Phase ◽  
Ground Station ◽  
Source Regions ◽  
Background Magnetic Field ◽  
Injection Region ◽  
Wave Normal ◽  
Northern And Southern Hemispheres ◽  
Emic Waves

Abstract. During the storm recovery phase on August 27, 2018, the China Seismo-Electromagnetic Satellite (CSES) detected Pc1 wave activities both in the Northern and Southern hemispheres in the high latitude post-midnight ionosphere with a central frequency about 2 Hz. Meanwhile, the typical Pc1 waves were simultaneously observed by the Sodankylä Geophysical Observatory (SGO) stations on the ground for several hours. In this paper, we study the propagation characteristics and possible source regions of those waves. Firstly, we find that the satellites observed Pc1 waves exhibit mixed polarization and the wave normal is almost parallel with the background magnetic field. The field-aligned Poynting fluxes point downward in both hemispheres, implying the satellites are close to the wave injection regions in the ionosphere at about L = 3. Furthermore, we also find that the estimated position of the plasmapause calculated by models is almost at L = 3. Therefore, we suggest the possible sources of waves are near the plasmapause, which is consistent with previous studies that the outward expansion of the plasmasphere into the ring current during the recovery phase of geomagnetic storms may generate electromagnetic ion cyclotron (EMIC) waves and then these EMIC waves propagate along the background magnetic field northward and southward to the ionosphere at about L = 3. Additionally, the ground station data show that Pc1 wave power attenuates with increasing distance from L = 3, supporting the idea that CSES observes the wave activities near the injection region. The observations are unique in that the Pc1 waves are observed in the ionosphere in nearly conjugate regions, where transvers Alfven waves propagate down into the ionosphere.

scholarly journals Titan's magnetic field signature during the Cassini T34 flyby: Comparison between hybrid simulations and MAG data

2008 ◽  
Vol 35 (4) ◽  
Author(s):  
S. Simon ◽  
U. Motschmann ◽  
G. Kleindienst ◽  
K.-H. Glassmeier ◽  
C. Bertucci ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Hybrid Simulations

scholarly journals Ionospheric Pc1 waves during a storm recovery phase observed by the China Seismo-Electromagnetic Satellite

2020 ◽  
Vol 38 (3) ◽  
pp. 775-787
Author(s):  
Xiaochen Gou ◽  
Lei Li ◽  
Yiteng Zhang ◽  
Bin Zhou ◽  
Yongyong Feng ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Storms ◽  
Recovery Phase ◽  
Central Frequency ◽  
Ground Station ◽  
Source Regions ◽  
Background Magnetic Field ◽  
Injection Region ◽  
Wave Normal ◽  
Emic Waves

Abstract. During the storm recovery phase on 27 August 2018, the China Seismo-Electromagnetic Satellite (CSES) detected Pc1 wave activities in both the Northern Hemisphere and Southern Hemisphere in the high-latitude, post-midnight ionosphere with a central frequency of about 2 Hz. Meanwhile, the typical Pc1 waves were simultaneously observed for several hours by the Sodankylä Geophysical Observatory (SGO) stations on the ground. In this paper, we study the propagation characteristics and possible source regions of those waves. Firstly, we find that the Pc1 waves observed by the satellites exhibited mixed polarisation, and the wave normal is almost parallel with the background magnetic field. The field-aligned Poynting fluxes point downwards in both hemispheres, implying that the satellites are close to the wave injection regions in the ionosphere at about L=3. Furthermore, we also find that the estimated position of the plasmapause calculated by models is almost at L=3. Therefore, we suggest that the possible sources of waves are near the plasmapause, which is consistent with previous studies in that the outward expansion of the plasmasphere into the ring current during the recovery phase of geomagnetic storms may generate electromagnetic ion cyclotron (EMIC) waves, and these EMIC waves propagate northwards and southwards along the background magnetic field to the ionosphere at about L=3. Additionally, the ground station data show that Pc1 wave power attenuates with increasing distance from L=3, supporting the idea that the CSES observes the wave activities near the injection region. The observations are unique in that the Pc1 waves are observed in the ionosphere in nearly conjugate regions where transverse Alfvén waves propagate down into the ionosphere.

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