Radio relics are extended regions of synchrotron radio emission that have been found in the outskirts of a few dozen galaxy clusters. Relics are often associated with clusters undergoing merger activity. They are not associated optically with a...
This thesis presents two-fluid simulations of forced magnetic reconnection with finite electron inertia in two and three dimensional periodic systems. Reconnection in the system is driven by a spatially localized forcing function, added to the ion...
The discovery of the Van Allen radiation belts in the 1958 was the first major discovery of the Space Age. There are two belts of energetic particles. The inner belt is very stable, but the outer belt is extremely variable, especially during...
Whistler-mode chorus waves have recently drawn tremendous attention as an important mechanism for controlling the energetic electron flux in Earthâ€™s radiation belt. This dissertation aims to answer questions about whistler-mode chorus waves, such...
Magnetic fields at all scales are prevalent in our universe. However, current cosmological models predict that initially the universe was bereft of large-scale fields. Standard magnetohydrodynamics (MHD) does not permit magnetogenesis; in the MHD...
Van Allen radiation belts -- Mathematical models. Electrons -- Diffusion -- Mathematical models. Magnetohydrodynamic waves -- Mathematical models.
It is becoming increasingly important to understand the dynamics of radiation belt energetic particles given their potentially hazardous effects on satellites and our ever-increasing dependence on those satellites. There is a need to determine...
In this thesis data from four sounding rocket experiments (PHAZE II, SIERRA, RACE and HIBAR) are used to explore the high and medium frequency waves seen in the auroral ionosphere. All rockets were launched into active aurora and carried both...
We present results from a modeling effort of simple shock phenomena in the Cygnus Loop and Cassiopeia A. Using multi-epoch MDM observations of a small, isolated cloud in the southwest region of the Cygnus Loop, we measure the velocity of the...
In this thesis we review the methods for computation of cosmological correlations in the early universe known as the in-in formalism which are then applied to the problem of magnetogenesis from inflation. For this computation, a power-law single...
The thesis is devoted to the effects of electromagnetic coupling between the Earth's magnetosphere and the active auroral ionosphere. The research has been focused, in particular, on the concept of ionospheric feedback instability. The feedback...
Auroras -- Alaska -- Observations. Magnetospheric currents. Electric currents. Magnetic fields.
Auroral downward-current regions balance the upward currents of visible auroral arcs. FAST satellite data show conclusive evidence to confirm that these downward current regions (DCR) contain positive potential structures with diverging DC electric...
Loss processes greatly impact the dynamics of the Earth's radiation belts. In 1996, a balloon-borne germanium detector flown over Kiruna, Sweden detected the first terrestrial X-rays with energies on the order of 1 MeV. The spectrum for these...
Space plasmas. ; Magnetopause. ; Solar wind. ; Magnetic flux. ; Plasma astrophysics.
Two types of two-dimensional (2-D), coherent (time-stationary) space plasma structures, described by one-fluid, magnetostatic and isotropic plasma theory, are examined. One is the internal structure of the Earth's magnetopause and the other is...
Electric fields in the high-latitude regions of Earth's ionosphere are an important component of the coupled magnetosphere-ionosphere-thermosphere system. Characterizing the average behavior of these fields (or the corresponding drifts) is useful...
Magnetosphere -- Mathematical models. Magnetic reconnection -- Mathematical models.
In this thesis we present the results of two studies of magnetic reconnection at the dayside magnetopause using the Lyon-Fedder-Mobarry magnetospheric simulation code. The first study examined the global properties of reconnection as a function of...
Predictive control. Adaptive control systems -- Design. Airplanes -- Control systems.
A direct method to design data-based model predictive controllers is presented. The design method uses system identification techniques to identify model predictive controller gains directly from a set of excitation input and disturbance corrupted...
The ability to forecast the weather of the geospace environment depends critically on the ability to accurately model the dynamics of the coupled magnetosphere-ionosphere (MI) system. The MI interaction involves a set of electrodynamic and plasma...
Numerical modeling of the global heliosphere provides key insights into the physics of the outer heliosphere. The solar wind data utilized by these models impacts their accuracy and should be as close as possible to the actual solar wind. Ideally,...
The ionosphere is an important source of plasma in the magnetosphere, especially during geomagnetic storms. While satellite data has confirmed this population of ions, their effect on the dynamics of the magnetosphere-ionosphere (MI) system is not...
Two auroral sounding rocket case studies, one in the dayside and one in the nightside, explore aspects of poleward boundary aurora. The nightside sounding rocket, Cascades-2 was launched on 20 March 2009 at 11:04:00 UT from the Poker Flat Research...
There is a renewed interest in the study of the radiation belts with the recent launch of the Van Allen Probes satellites. The mechanisms that drive the global response of the radiation belts to geomagnetic storms are not yet well understood....
Currently, the hypothesis that discrete auroral arcs are produced by fluxes of magnetospheric electrons accelerated along the ambient magnetic field into the ionosphere by linear/non-linear mechanisms associated with magnetic field-aligned currents...
Strong evidence exists showing that stellar evolution models are unable to accurately predict the fundamental properties of low-mass stars. Observations of low-mass stars in detached eclipsing binaries (DEBs) indicate that stellar models...
The resonant excitation of low-frequency MHD waves by energetic ring current ions has been studied by means of hybrid MHD-gyrokinetic particle simulations. The purpose of the investigation is to identify the instability mechanism for internally...
Most theoretical and computational studies of turbulence in Navier-Stokes fluids and/or guiding-center plasmas have been carried out in the presence of spatially periodic boundary conditions. In view of the frequently-reproduced result that...
Van Allen radiation belts -- Mathematical models. ; Magnetosphere -- Mathematical models. ; Magnetohydrodynamics -- Mathematical models.
The physics of geomagnetically-trapped radiation has been a topic of interest since the discovery of the Van Allen belts in 1958. As the energetic particles comprising these belts can pose a hazard to human activity in space, considerable effort...