Combined scattering loss of radiation belt relativistic electrons by simultaneous three-band EMIC waves: A case study

2016 ◽  
Vol 121 (5) ◽  
pp. 4446-4451 ◽  
Author(s):  
Fengming He ◽  
Xing Cao ◽  
Binbin Ni ◽  
Zheng Xiang ◽  
Chen Zhou ◽  
...  
Keyword(s):  
Radiation Belt ◽  
Relativistic Electrons ◽  
Scattering Loss ◽  
Emic Waves

scholarly journals Trapping and amplification of unguided mode EMIC waves in the radiation belt

2021 ◽  
Author(s):  
Geng Wang ◽  
Zhonglei Gao ◽  
Mingyu Wu ◽  
Guoqiang Wang ◽  
Sudong Xiao ◽  
...  
Keyword(s):  
Radiation Belt ◽  
Abundance Ratio ◽  
Relativistic Electrons ◽  
Scattering Loss ◽  
Propagation Behavior ◽  
Guided Mode ◽  
Waves Propagation ◽  
Spatial Locations ◽  
First Time ◽  
Emic Waves

Abstract Electromagnetic ion cyclotron (EMIC) waves can cause the scattering loss of the relativistic electrons in the earth's radiation belt. They can be classified into the guided mode and the unguided mode, according to waves propagation behavior. The guided mode waves have been widely investigated in the radiation belt, but the observation of the unguided mode waves have not been expected. Based on the observations of Van Allen Probes, we demonstrate for the first time the existence of the intense unguided mode EMIC waves. The reflection interface formed by the spatial locations of local helium cutoff frequencies can be nearly parallel to the equatorial plane when the proton abundance ratio decreases sharply with L-shell. This structure combined with the anisotropic hot protons can lead to the trapping and significant amplification of the unguided mode waves. These results may help to understand the nature of EMIC waves in the radiation belt.

Interactions between H+band EMIC waves and radiation belt relativistic electrons: Comparisons of test particle simulations with quasi-linear calculations

2019 ◽  
Vol 26 (3) ◽  
pp. 032901 ◽  
Author(s):  
Song Fu ◽  
Binbin Ni ◽  
Xin Tao ◽  
Yasong Ge ◽  
Jiang Liu ◽  
...  
Keyword(s):  
Test Particle ◽  
Radiation Belt ◽  
Relativistic Electrons ◽  
Particle Simulations ◽  
Emic Waves

scholarly journals Rapid Loss of Radiation Belt Relativistic Electrons by EMIC Waves

2017 ◽  
Vol 122 (10) ◽  
pp. 9880-9897 ◽  
Author(s):  
Zhenpeng Su ◽  
Zhonglei Gao ◽  
Huinan Zheng ◽  
Yuming Wang ◽  
Shui Wang ◽  
...  
Keyword(s):  
Radiation Belt ◽  
Relativistic Electrons ◽  
Rapid Loss ◽  
Emic Waves

Statistical EMIC diffusion models calculated by averaging observation specific diffusion coefficients

2021 ◽  
Author(s):  
Johnathan Ross ◽  
Sarah Glauert ◽  
Richard Horne ◽  
Nigel Meredith ◽  
Clare Watt
Keyword(s):  
Diffusion Coefficients ◽  
Radiation Belt ◽  
Diffusion Models ◽  
Relativistic Electrons ◽  
Particle Interactions ◽  
Resonant Wave ◽  
Van Allen Probes ◽  
Through Diffusion ◽  
Wave Particle Interactions ◽  
Emic Waves

<p>Electromagnetic ion cyclotron (EMIC) waves play an important role in relativistic electron losses in the radiation belts through diffusion via resonant wave-particle interactions. We present a new statistical model of electron diffusion by EMIC waves calculated, using Van Allen Probe observations, by averaging observation specific diffusion coefficients. The resulting diffusion coefficients therefore capture a wider range of wave-particle interactions than previous average models which are calculated using average observations. These calculations, and their role in radiation belt simulations, are then compared against existing diffusion models. The new diffusion coefficients are found to significantly improve the agreement between the calculated decay of relativistic electrons and Van Allen Probes data.</p><p> </p>

scholarly journals Discovery of proton hill in the phase space during interactions between ions and electromagnetic ion cyclotron waves

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Masafumi Shoji ◽  
Yoshizumi Miyoshi ◽  
Lynn M. Kistler ◽  
Kazushi Asamura ◽  
Ayako Matsuoka ◽  
...  
Keyword(s):  
Phase Space ◽  
Interaction Analysis ◽  
Particle Interaction ◽  
Observational Evidence ◽  
Frequency Drift ◽  
Frequency Change ◽  
Relativistic Electrons ◽  
Scattering Loss ◽  
Ion Cyclotron ◽  
Emic Waves

AbstractA study using Arase data gives the first observational evidence that the frequency drift of electromagnetic ion cyclotron (EMIC) waves is caused by cyclotron trapping. EMIC emissions play an important role in planetary magnetospheres, causing scattering loss of radiation belt relativistic electrons and energetic protons. EMIC waves frequently show nonlinear signatures that include frequency drift and amplitude enhancements. While nonlinear growth theory has suggested that the frequency change is caused by nonlinear resonant currents owing to cyclotron trapping of the particles, observational evidence for this has been elusive. We survey the wave data observed by Arase from March, 2017 to September 2019, and find the best falling tone emission event, one detected on 11th November, 2017, for the wave particle interaction analysis. Here, we show for the first time direct evidence of the formation of a proton hill in phase space indicating cyclotron trapping. The associated resonance currents and the wave growth of a falling tone EMIC wave are observed coincident with the hill, as theoretically predicted.

Nonlinear Interactions Between Relativistic Electrons and EMIC Waves in Magnetospheric Warm Plasma Environments

2020 ◽  
Vol 125 (12) ◽  
Author(s):  
Jiang Yu ◽  
L. Y. Li ◽  
Jun Cui ◽  
J. B. Cao ◽  
Jing Wang ◽  
...  
Keyword(s):  
Relativistic Electrons ◽  
Nonlinear Interactions ◽  
Warm Plasma ◽  
Emic Waves

scholarly journals A subauroral polarization stream driven by field‐aligned currents associated with precipitating energetic ions caused by EMIC waves: A case study

2016 ◽  
Vol 121 (2) ◽  
pp. 1696-1705 ◽  
Author(s):  
Zhigang Yuan ◽  
Ying Xiong ◽  
Zheng Qiao ◽  
Haimeng Li ◽  
Shiyong Huang ◽  
...  
Keyword(s):  
Energetic Ions ◽  
Emic Waves

Direct measurements of cold and hot plasma composition and EMIC waves in the outer magnetosphere: Implications for inner magnetosphere wave-particle interactions

2021 ◽  
Author(s):  
Justin Lee ◽  
Drew Turner ◽  
Sarah Vines ◽  
Robert Allen ◽  
Sergio Toledo-Redondo
Keyword(s):  
Unstable Wave ◽  
Linear Wave ◽  
Plasma Composition ◽  
Inner Magnetosphere ◽  
Hot Plasma ◽  
Emic Wave ◽  
Direct Measurements ◽  
Wave Numbers ◽  
Emic Waves

<p>Although thorough characterization of magnetospheric ion composition is rare for EMIC wave studies, convective processes that occur more frequently in Earth’s outer magnetosphere have allowed the Magnetospheric Multiscale (MMS) satellites to make direct measurements of the cold and hot plasma composition during EMIC wave activity. We will present an observation and linear wave modeling case study conducted on EMIC waves observed during a perturbed activity period in the outer dusk-side magnetosphere. During the two intervals investigated for the case study, the MMS satellites made direct measurements of cold plasmaspheric plasma in addition to multiple hot ion components at the same time as EMIC wave emissions were observed. Applying the in-situ plasma composition data to wave modeling, we find that wave growth rate is impacted by the complex interactions between the cold as well as the hot ion components and ambient plasma conditions. In addition, we observe that linear wave properties (unstable wave numbers and band structure) can significantly evolve with changes in cold and hot ion composition. Although the modeling showed the presence of dense cold ions can broaden the range of unstable wave numbers, consistent with previous work, the hot heavy ions that were more abundant nearer storm main phase could limit the growth of EMIC waves to smaller wave numbers. In the inner magnetosphere, where higher cold ion density is expected, the ring current heavy ions could also be more intense near storm-time, possibly resulting in conditions that limit the interactions of EMIC waves with trapped radiation belt electrons to multi-MeV energies. Additional investigation when direct measurements of cold and hot plasma composition are available could improve understanding of EMIC waves and their interactions with trapped energetic particles in the inner magnetosphere.</p>

Radial diffusion coefficients database in the frame of SafeSpace project

2021 ◽  
Author(s):  
Christos Katsavrias ◽  
Ioannis A. Daglis ◽  
Afroditi Nasi ◽  
Constantinos Papadimitriou ◽  
Marina Georgiou
Keyword(s):  
Diffusion Coefficients ◽  
Radiation Belt ◽  
Field Measurements ◽  
Radial Diffusion ◽  
Relativistic Electrons ◽  
Outer Radiation Belt ◽  
Horizon 2020 ◽  
Research And Innovation ◽  
The Difference ◽  
Cycle 24

<p>Radial diffusion has been established as one of the most important mechanisms contributing the acceleration and loss of relativistic electrons in the outer radiation belt. Over the past few years efforts have been devoted to provide empirical relationships of radial diffusion coefficients (D<sub>LL</sub>) for radiation belt simulations yet several studies have suggested that the difference between the various models can be orders of magnitude different at high levels of geomagnetic activity as the observed D<sub>LL</sub> have been shown to be highly event-specific. In the frame of SafeSpace project we have used 12 years (2009 – 2020) of multi-point magnetic and electric field measurements from THEMIS A, D and E satellites to create a database of calculated D<sub>LL</sub>. In this work we present the first statistics on the evolution of D<sub>LL </sub>during the various phases of Solar cycle 24 with respect to the various solar wind parameters and geomagnetic indices.</p><p>This work has received funding from the European Union's Horizon 2020 research and innovation programme “SafeSpace” under grant agreement No 870437.</p>

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