Browsing by Department "Physics"
Now showing items 81-100 of 101
The role of excited state electron-impact ionization and configuration mixing in the population modeling of neutral Ne and W in fusion-capable plasmas using large-scale R-matrix collisional data
(2019-12-09)
This work reports on large-scale non-perturbative \textit{R}-matrix quantum mechanical calculations for neutral neon and tungsten. In addition, generalized collisional-radiative modeling of neutral neon and tungsten is ...
Silicon Carbide/Aluminum Oxide Field-Effect Transistors
(2020-07-22)
4H-Silicon Carbide is a wide band gap semiconductor with attractive physical properties for high power, high-frequency devices, and electronics that operate under harsh environments that are not accessible to conventional ...
Simulation of Pickup ions - Local Interstellar Medium Interactions in the Outer Heliosphere
(2021-11-29)
The energetic neutral atoms (ENAs) received by Interstellar Boundary Explorer (IBEX) shows a ribbon structure of the ENA source around the heliopause, the plasma boundary of solar system. The reason behind it is still a ...
Simulations of Sawtoothing in the CTH Stellarator-Tokamak Hybrid
(2016-07-28)
Numerical extended MHD simulations are used to gain insight into the effect of three-dimensional shaping from the Compact Toroidal Hybrid (CTH) stellarator field on sawteeth. Numerical solutions having repeated sawtooth ...
Simulations of the Compact Toroidal Hybrid Using the Finite Element Extended MHD Code NIMROD
(2015-07-29)
Magnetohydrodynamic (MHD) modeling of magnetic confinement devices is an important tool in the understanding of plasma processes. With the nearly axisymmetric tokamak being the leading candidate for a plasma fusion reactor, ...
A spectroscopic neutral density diagnostic and exploration of the role of metastable states in fusion and astrophysical plasmas
(2023-12-04)
Understanding the transition region between fully ionized and neutrally dominated plasmas is important to the study of the magnetosphere of the earth, the corona/chromosphere transition regions of the sun, and detached ...
Spontaneous Electromagnetic Emission from a Strongly Localized Plasma Flow
(2011-04-29)
The laboratory experiments described in this dissertation establish that strongly localized DC electric fields perpendicular to the ambient magnetic field can behave as a radiation source for electromagnetic ion cyclotron ...
STRAHL modeling of iron impurity transport with on- and off-axis heating during the first divertor campaign on Wendelstein 7-X
(2021-12-07)
Impurity transport characterization and ultimately impurity control is critical to the future prospects of magnetic confinement fusion energy.
In particular for an optimized stellarator like Wendelstein 7-X the characterization ...
Study of Sb surface doping and borosilicate glass gate dielectric for 4H-SiC MOSFETs
(2017-11-28)
Silicon carbide (SiC) is a compound material with a wide bandgap, high critical electric
field strength, high saturation drift velocity and high thermal conductivity, which makes it an
outstanding material among wide ...
Surface and Interfacial Studies of Perovskite Oxides Grown by Hybrid Molecular Beam Epitaxy
(2022-04-19)
Perovskite oxides are well known for their intriguing properties such as ferroelectricity, ferromagnetism, and superconductivity that can be tuned by different crystalline degrees of freedom. SrTiO3 (STO) is a perovskite ...
Synthesis and Characterization of Mn-based Spinels Grown by Molecular Beam Epitaxy
(2022-05-02)
A developed energy infrastructure that relies predominately on renewable energy is critical to the longevity of society. Water-splitting and fuel cell devices will have a place in this infrastructure, although this technology ...
Theoretical modeling combined with experimental spectroscopic measurements for the diagnosis of high-Z erosion and transport applications in plasmas
(2020-12-11)
Understanding plasma-material interaction (PMI) continues to be a challenge for future
fusion reactors. High-Z materials (e.g. tungsten, molybdenum) have emerged as leading
solutions for plasma facing materials. Erosion ...
Theoretical Study of Pressure-Induced Phase Transitions and Thermal Properties for Main-Group Oxides and Nitrides
(2009-08-03)
Main group nitrides and oxides are important solid compounds with applications in fields ranging from structural ceramics to catalysts and electronic materials. We have theoretically investigated the pressure-induced phase ...
Theoretical Study of Thermal Properties and Thermal Conductivities of Crystals
(2008-08-15)
Standard first-principles total energy and force calculations were extended to the calculations of harmonic force constant matrices and third order lattice anharmonicity tensors with an efficient super-cell finite-difference ...
Thermal Diffusion of Dopants in Silicon Carbide
(2012-07-27)
Despite considerable advancement in SiC material and device technology, there are still vital issues to be resolved such as metallization and doping. In SiC, ohmic contacts require high concentration doping. Commonly used ...
Three-Dimensional Hybrid Simulation Of Dayside Magnetic Reconnection
(2011-04-27)
With a three dimensional (3-D) global hybrid simulation model, we
investigate magnetopause reconnection and the energy spectra of cusp precipitating ions under different IMF conditions.
First, the magnetic configuration ...
Time-Dependent Studies of Fundamental Atomic Processes in Rydberg Atoms
(2007-08-15)
This dissertation consists of four time-dependent studies of various fundamental
atomic processes involving highly excited atoms and ions. We use time-dependent
close-coupling theory besides other perturbative and and ...
Transmission-Type Impedance Probes for Use in Complex Plasmas
(2023-12-04)
Impedance probes measure electron density (ne ) and electron temperature (Te) by interpreting frequency-dependent transmission or reflection spectra (S21 or S11) of radiofrequency (RF) signals of low power (10−5 W). This ...
Transport Properties of 2D Heterostructures Determined via First Principles Calculations
(2023-08-03)
Atomically thin, two-dimensional materials have demonstrated their great potentials in nanoelectronics due to their mechanical and optoelectronic properties. With atomic layers free of dangling bonds, these materials possess ...
Tunneling Current and Topographical Measurements of Semiconducting Structures Relevant for Electronic Applications using Atomic Force Microscopy
(2017-07-27)
This thesis is a combination of a synopsis of techniques used in Atomic Force Microscopy and its subsidiary uses as well as a record of experimental data taken using the instrument for two separate experiments. The first ...