College of Sciences and Mathematics: Recent submissions
Now showing items 281-300 of 389
Study of EMIC wave excitation using direct ion measurements
(2020-06-05)
With data from Van Allen Probes, we investigate electromagnetic ion cyclotron (EMIC) wave excitation using simultaneously observed ion distributions. Strong He band waves occurred while the spacecraft was moving through ...
Fast magnetosonic waves driven by shell velocity distributions
(2020-06-05)
Using linear dispersion theory and particle-in-cell simulations, we explore the ion Bernstein instability driven by the shell-type ion velocity distribution which is related to the excitation of fast magnetosonic waves in ...
Dipolarization fronts as earthward propagating flux ropes: A three-dimensional global hybrid simulation
(2020-06-03)
Dipolarization fronts (DFs) as earthward propagating flux ropes (FRs) in the Earth's magnetotail are presented and investigated with a three-dimensional (3-D) global hybrid simulation for the first time. In the simulation, ...
Regime transition of ion Bernstein instability driven by ion shell velocity distributions
(2020-06-03)
Linear kinetic dispersion theory is used to investigate a regime transition of the ion Bernstein instability driven by a proton velocity distribution with positive slopes with respect to the perpendicular velocity, ...
Proton velocity ring-driven instabilities in the inner magnetosphere: Linear theory and particle-in-cell simulations
(2020-06-03)
Linear dispersion theory and electromagnetic particle-in-cell (PIC) simulations are used to investigate linear growth and nonlinear saturation of the proton velocity ring-driven instabilities, namely, ion Bernstein instability ...
Scalings of Alfven-cyclotron and ion Bernstein instabilities on temperature anisotropy of a ring-like velocity distribution in the inner magnetosphere
(2020-06-03)
A ring-like proton velocity distribution with f(p)(v)/v>0 and which is sufficiently anisotropic can excite two distinct types of growing modes in the inner magnetosphere: ion Bernstein instabilities with multiple ion ...
Statistical correlation of low-altitude ENA emissions with geomagnetic activity from IMAGE/MENA observations
(2020-06-03)
Plasma sheet particles transported Earthward during times of active magnetospheric convection can interact with exospheric/thermospheric neutrals through charge exchange. The resulting Energetic Neutral Atoms (ENAs) are ...
Understanding the growth rate patterns of ion Bernstein instabilities driven by ring-like proton velocity distributions
(2020-06-03)
Fast magnetosonic waves in Earth's inner magnetosphere, which have as their source ion Bernstein instabilities, are driven by hot proton velocity distributions (f(p)) with partial derivative f(p)(v(perpendicular to))/partial ...
Ion Bernstein instability dependence on the proton-to-electron mass ratio: Linear dispersion theory
(2020-06-03)
Fast magnetosonic waves, which have as their source ion Bernstein instabilities driven by tenuous ring-like proton velocity distributions, are frequently observed in the inner magnetosphere. One major difficulty in the ...
Kinetic Alfven waves in three-dimensional magnetic reconnection
(2020-06-03)
Alfvenic waves are believed to be fundamentally important in magnetic reconnection. Kinetic dynamics of particles can break the Alfven speed limit in the evolution and propagation of perturbations during reconnection. In ...
Global images of trapped ring current ions during main phase of 17 March 2015 geomagnetic storm as observed by TWINS
(2020-06-03)
A unique view of the trapped particles in the inner magnetosphere provided by energetic neutral atom (ENA) imaging is used to observe the dynamics of the spatial structure and the pitch angle anisotropy on a global scale ...
Hall effect control of magnetotail dawn-dusk asymmetry: A three-dimensional global hybrid simulation
(2020-06-03)
Magnetotail reconnection and related phenomena (e.g., flux ropes, dipolarizing flux bundles, flow bursts, and particle injections) occur more frequently on the duskside than on the dawnside. Because this asymmetry can ...
Rapid evolution of disease resistance is accompanied by functional changes in gene expression in a wild bird
(2020-06-03)
Wild organisms are under increasing pressure to adapt rapidly to environmental changes. Predicting the impact of these changes on natural populations requires an understanding of the speed with which adaptive phenotypes ...
Reproductive Value and the Stochastic Demography of Age-Structured Populations
(2020-06-03)
The dynamics of an age-structured population in a fluctuating environment is determined by the stochastic individual contributions from annual survival and fecundity to the total reproductive value of the population the ...
Scalings for the Alfven-cyclotron instability: Linear dispersion theory and hybrid particle-in-cell simulations
(2020-06-01)
The Alfven-cyclotron instability is driven by an ion temperature anisotropy such that T-perpendicular to/T-|| >1 where and || denote directions perpendicular and parallel to a uniform background magnetic field B-o, ...
Cross-scale observations of the 2015 St. Patrick's day storm: THEMIS, Van Allen Probes, and TWINS
(2020-06-01)
We present cross-scale magnetospheric observations of the 17 March 2015 (St. Patrick's Day) storm, by Time History of Events and Macroscale Interactions during Substorms (THEMIS), Van Allen Probes (Radiation Belt Storm ...
Ion Bernstein instability as a possible source for oxygen ion cyclotron harmonic waves
(2020-06-01)
This paper demonstrates that an ion Bernstein instability can be a possible source for recently reported electromagnetic waves with frequencies at or near the singly ionized oxygen ion cyclotron frequency, Omega(+)(O), and ...
Spectral properties and associated plasma energization by magnetosonic waves in the Earth's magnetosphere: Particle-in-cell simulations
(2020-06-01)
In this paper, we perform a 1-D particle-in-cell (PIC) simulation model consisting of three species, cold electrons, cold ions, and energetic ion ring, to investigate spectral structures of magnetosonic waves excited by ...
Foreshock wave interaction with the magnetopause: Signatures of mode conversion
(2020-06-01)
Our previous hybrid simulation (Shi et al., 2013) under a radial interplanetary magnetic field (IMF) and a supercritical solar wind Mach number has shown that foreshock compressional waves originated from the quasi-parallel ...
The ion temperature gradient: An intrinsic property of Earth's magnetotail
(2020-06-01)
Although the ion temperature gradient along (X GSM) and across (Z GSM) the Earth's magnetotail, which plays a key role in generating the cross‐tail current and establishing pressure balance with the lobes, has been extensively ...