Superconductivity is a phenomenon that has been fascinating scientists, engineers, and the general public since its discovery in 1911. Many people associate the properties of superconductors with the astonishing demonstration of a levitating magnet over a superconductor when it is cooled down below its transition temperature. We now know that superconductivity is a very common phenomenon present in many metals in the periodic table. It was not until 1986 that superconductivity above about 30 K was discovered, giving birth to the era of high temperature superconductors. Today many applications take advantage of this property, ranging from medical instrumentation, transportation, high energy particle accelerators, to digital and analog electronics. Most of the applications fall within two well differentiated uses of superconductors, for which different properties are being exploited. One example is the use of superconductors to generate very large static magnetic fields, which usually employ newly discovered high temperature superconductors, taking advantage of their very large upper critical magnetic field. Alternatively, applications involving high-power microwaves usually rely on superconductors with high lower critical magnetic field, for which niobium is commonly the material of choice. Almost a century after the discovery of superconductivity, this dissertation explores potential new possibilities for high power microwave superconducting applications. First, we study and model a new method of determining the magnetic critical field of superconducting materials at microwave frequencies. Subsequently, we numerically study the theoretical performance of multilayer structures composed of alternating superconducting and dielectric materials. These structures theoretically allow us to sustain higher magnetic fields than niobium at microwave frequencies.

Planetary dynamos are responsible for the generation of large-scale magnetic fields and are ubiquitous in the solar system. Magnetic fields generated by dynamo action in a planetary core offer unique insight into the internal structure, composition, and energetics of the planet. This dissertation consists of two main parts, the first focuses on long period fluctuations in Earth’s magnetic field and the second explores conditions for dynamo action in the cores of terrestrial exoplanets. The first part consists of three projects using first-principle numerical magnetohydrodynamic models of the geodynamo to investigate the relationship between two fundamental, but poorly understood, aspects of the geomagnetic field: magnetic polarity reversals and the influence of core evolution. The first project explores the dependence of various dynamo properties on the relative strengths of buoyancy and rotation, and identifies several dynamical regimes whose magnetic field fluctuations over time are consistent with the paleomagnetic field. We find that normal evolution of buoyancy production in the core and planetary rotation rate over 100 Myr produce a negligible change in dynamo polarity reversal rate and field intensity, implying that the observed fluctuations in the geomagnetic reversal rate requires either anomalous core evolution or a rough dynamo regime boundary. The second project models the long time-scale evolution of the Earth’s core using time-dependent control parameters, which are constrained by the secular cooling of the core and tidal deceleration. We find that fluctuations in the geodynamo are closely coupled to the evolution of the core, which implies a connection between the long time-scale trends in the seafloor geomagnetic polarity reversal rate and the rate of core evolution over the last 100 Myr. In the third project we investigate the hypothesis that the long period (&sim；200 Myr) oscillation in paleomagnetic reversal frequency is controlled by the heat flow amplitude at the core-mantle boundary (CMB) by calculating a continuous 200 Myr long geodynamo simulation subject to an oscillation in core heat flow. We demonstrate that an increase in the superadiabatic core heat flow evolves the model from a superchron to a reversing state, and vice-versa, producing a simulated reversal record similar to the seafloor paleomagnetic reversal record. This implies that fluctuations in the thermal evolution of the core are recorded in the paleomagnetic record, with periods of high core heat flow corresponding to frequent polarity reversals, similar to the present-day geomagnetic reversal rate (&sim；4 Myr–1), and periods of low heat flow corresponding to superchron states with no polarity reversals, similar to the CNS. In the second part we explore the conditions for dynamo action in the core’s of terrestrial exoplanets and the possibility of their detection. We construct internal structure models for terrestrial exoplanets with 1-10 Earth masses and an Earth-like composition and structure. In order to maximize the magnetic field intensity at the planet surface, which is maintained by dynamo action in the convecting core, we assume these planets are in an optimal thermal state where the temperature profile in the mantle thermal boundary layers is at the silicate melting point. We find that magnetic field intensity increases slightly with mass and core size, such that the maximum magnetic dipole moment is about 23 times the geomagnetic dipole moment for a 10 Earth-mass planet with a large core. We find that estimates of the electron cyclotron emission spectrum for nearby exoplanet magnetic fields are generally below the current detection thresholds of the largest radio telescopes, but may be detectable in the future.

Magnetic Resonance MR) imaging is one of the most powerful tools in diagnostic medicine for soft tissue imaging. Image acquisition techniques and hardware receivers are very important in achieving high contrast and high resolution MR images. An aim of this dissertation is to design single and multi-element room and cryogenic temperature arrays and make assessments of their signal-to-noise ratio SNR) and SNR gain. In this dissertation, four sets of MR receiver coils are built. They are the receiver-only cryo-coils that are not commercially available. A tuning and matching circuit is attached to each coil. The tuning and matching circuits are simple； however, each device component has to operate at a high magnetic field and cryogenic temperature environment. Remote DC bias of the varactor controls the tuning and matching outside the scanner room. Active detuning of the resonator is done by two p-i-n junction PIN) diodes. Cooling of the receiver is done by a customized liquid nitrogen cryostat. The first application is to build a 3-Tesla 2×1 horseshoe counter-rotating current CRC) cryogenic array to image the tibia in a human body. With significant increase in SNR, the surface coil should deliver high contrast and resolution images that can show the trabecular bone and bone marrow structure. This structural image will be used to model the mechanical strength of the bone as well as bone density and chance of fracture. The planar CRC is a unique design of this surface array. The second application is to modify the coil design to 7-Tesla to study the growth of infant rhesus monkey eyes. Fast scan MR images of the infant monkey heads are taken for monitoring shapes of their eyeballs. The monkeys are induced with shortsightedness by eye lenses, and they are scanned periodically to get images of their eyeballs. The field-of-view FOV) of these images is about five centimeters and the area of interest is two centimeters deep from the surface. Because of these reasons, the MR counter-rotating current coil is sufficient and demonstrated its simplicity over a phased array in this application.

The Canadian Light Source CLS), a particle accelerator experimental facility located in Saskatoon, Canada, uses a high energy electron beam to create synchrotron light, which is millions of times brighter than sunlight. A superconducting radio frequency SRF) cavity, which is kept at 4.5 K by a liquid helium LHe) bath, is used to maintain the momentum of the electron beam during operation. CLS engineers have questions about the operation and optimization of the LHe cryogenic system that provides this LHe bath, and a computer model of this system has been proposed. In this work, a computer model of part of the LHe cryogenic system including the SRF cryostat and its supply and return lines, is constructed. A modular approach is taken, combining separate models of the LHe supply line, gaseous helium GHe) return system, and the cryostat. The LHe supply line model is designed to accommodate two-phase flows, as some LHe boils before reaching the cryostat. Conservation of mass, momentum and energy are used along with modified equations of state in an iterative method to solve pipe flows. The cryostat model is based on an established boiling vessel model. Virtual PID controllers are implemented on the combined model to drive the level and pressure control valves in realistic fashion. The model is validated against data obtained at the CLS, and is then used to answer several questions posed by CLS staff. The void fraction of gas exiting the LHe supply line is found to be around 20%. Oscillations in LHe line boundary conditions are found to have little dynamic effect at the CLS due to small magnitudes, but it is demonstrated that steady-state or quasi-steady models for boiling two-phase flows are generally insufficient to describe the corresponding flow dynamics. It is found that increasing the pressure controller gains can improve performance. Also, a proposed new supply and return line configuration is examined, and it is found that these proposed line changes can not only improve control issues but can also increase the maximum LHe supply rate for the system.

Artificially structured composite metamaterials consist of sub-wavelength sized structures that exhibit unusual electromagnetic properties not found in nature. Since the first experimental verification in 2000, metamaterials have drawn considerable attention because of their broad range of potential applications. One of the most attractive features of metamaterials is to obtain negative refraction, termed left-handed materials or negative-index metamaterials, over a limited frequency band. Negative-index metamaterials at near infrared wavelength are fabricated with circular, elliptical and rectangular holes penetrating through metal/dielectric/metal films. All three negative-index metamaterial structures exhibit similar figure of merit； however, the transmission is higher for the negative-index metamaterial with rectangular holes as a result of an improved impedance match with the substrate-superstrate air-glass) combination. In general, the processing procedure to fabricate the fishnet structured negative-index metamaterials is to define the hole-size using a polymetric material, usually by lithographically defining polymer posts, followed by deposition of the constitutive materials and dissolution of the polymer liftoff processing). This processing fabrication of posts: multi-layer deposition: liftoff) often gives rise to significant sidewall-angle because materials accumulate on the tops of the posts that define the structure, each successive film deposition has a somewhat larger aperture on the bottom metamaterial film, giving rise to a nonzero sidewall-angle and to optical bianisotropy. Finally, we demonstrate a nanometer-scale, sub-picosecond metamaterial device capable of over terabit/second all-optical communication in the near infrared spectrum. We achieve a 600 fs device response by utilizing a regime of sub-picosecond carrier dynamics in amorphous silicon and &sim；70% modulation in a path length of only 124 nm by exploiting the strong nonlinearities in metamaterials. We identify a characteristic signature associated with the negative index resonance in the pump-probe signal of a fishnet structure. We achieve much higher switching ratios at the fundamental resonance &sim；70%) relative to the secondary resonance &sim；20%) corresponding to the stronger negative index at the fundamental resonance. This device opens the door to other compact, tunable, ultrafast photonic devices and applications.

There have been many different technology advancements with the invention of solid state electronics, leading to the digital era which has changed the way users employ electronic circuits. Antennas are no different； however, they are still analog devices. With the advancements in technology, antennas are being fabricated on much higher frequencies and with greater bandwidths, all while trying to keep size and weight to a minimum. Centimeter and millimeter wave technologies have evolved for many different radio frequency RF) applications. Microstrip patch antennas have been developed, as wire and tubular antenna elements are difficult to fabricate with the tolerances required at micro-wavelengths. Microstrip patch antennas are continuously being improved. These types of antennas are great for embedded or conformal applications where size and weight are of the essence and the ease of manufacturing elements to tight tolerances is important. One of the greatest benefits of patch antennas is the ease in creating an array. Many simulation programs have been created to assist in the design of patch antennas and arrays. However, there are still discrepancies between simulated results and actual measurements. This research will focus on these differences. It begins with a literature research of patch antenna design, followed by an assessment of simulation programs used for patch antenna design. The resulting antenna design was realized by the fabrication of an antenna from the Genesys software. Laboratory measurements of the real-world antenna are then compared to the theoretical antenna characteristics. This process is used to illustrate deficiencies in the software models and likely improvements that need to be made.

Due to the wide availability and usage of wireless devices and systems there have been and are concerns regarding their effects on the human body. Respective regulatory agencies have developed safety standards based on scientific research on electromagnetic (EM) exposure from wireless devices and antennas. The metric that quantifies the exposure level is called the Specific Absorption Rate (SAR). Wireless devices must satisfy the regulatory standards before being marketed. In the past, researchers have primarily focused on investigating the EM exposure from wireless devices that are used very near to the user’s head or body (less than 25 mm). But as time progressed many more wireless devices have become ubiquitous (vehicular wireless devices, laptop PCMCIA cards, Bluetooth dongles, wireless LAN routers, cordless phone base stations, and pico base stations are to name a few) and are operated at distances greater than 25 mm yet smaller than 200 mm. Given the variations in operating frequency, distance, and antenna size and type it is challenging to develop an approach using which EM exposure from a wide variety of wireless devices can be evaluated. The problem becomes more involved owing to the difficulties in identifying the antenna zone boundaries, e.g. reactive near-field, radiating near-field, far-field etc. The focus of this thesis is to investigate a large class of low and highly directive antennas and evaluate the EM exposure from them into a large elliptical phantom. The objective is to be able to predict threshold power levels that meet the SAR limits imposed by the regulatory agencies. It was observed that among the low directivity antennas at close near-field distances, electrically small antennas induced distinguishably higher SAR than electrically larger antennas. But differences in SAR were small as the phantom moved into the far-fields of the antennas. SAR induced by highly directive antennas were higher when the phantom was in the far-field of the antennas and was facing the antenna frontal plane. The same was not true when the phantom was in the near-field of the antennas. Finally, by analyzing the simulation and measurement data threshold power formulas were developed for low directivity antennas using which power levels corresponding to the safe exposure limits independent of device type or geometry can be estimated.

The United States Department of Defense tests its weapons systems to many different real as well as man-made environments prior to deploying the systems to the troops. The intent of testing is to insure the systems function as they are intended without adverse reactions. One of the required tests is a Radiation Hazards test to insure that nonionizing radio frequency waves generated by transmitters, such as radios and jammers, do not cause harm to personnel, ordnance or fuel. This test is typically performed at a DoD test lab and data taken at the lab is used to determine safe operating parameters for a particular piece of equipment. This thesis presents measurements as well as mathematical models to demonstrate methods that can be employed to take more relevant Radiation Hazards data.

The multidentate nature of pyrophosphate makes it an attractive ligand for complexation of metal cations. The participation of pyrophosphate in a variety of biological pathways and its metal catalyzed hydrolysis has driven our investigation into its coordination chemistry. We have successfully synthesized a library of binuclear pyrophosphate bridge coordination complexes. The problem of pyrophosphate hydrolysis to phosphate in the presence of divalent metal ions was overcome by incorporating capping ligands such as 1,10-phenanthroline and 2,2-bipyridine prior to the addition of the pyrophosphate. The magnetic properties of these complexes was investigated and magneto-structural analysis was conducted. The biological abundance of pyrophosphate and the success of metal based drugs such as cisplatin, prompted our investigation of the cytotoxic properties of MII) pyrophosphate dimeric complexes where MII) is CoII, CuII, and NiII) in adriamycin resistant human ovarian cancer cells. Thess compounds were found to exhibit toxicity in the nanomolar to picomolar range. We conducted in vitro stability studies and the mechanism of cytoxicity was elucidated by performing DNA mobility and binding assays, enzyme inhibition assays, and in vitro oxidative stress studies.

In many wireless devices, antennas occupy the majority of the overall size. As compact device sizes become a greater focus in industry, the demand for small antennas escalates. In this thesis, detailed investigations on the design of a planar meandered line antenna with truncated ground plane and 3D dipole antenna at 2.4 GHz (ISM band) are presented. The primary goal of this research is to develop small, low coast, and low profile antennas for wireless sensor applications. The planar meandered line antenna was designed based on a study of different miniaturization techniques and a study of the ground plane effect. The study of the ground plane effect proved that it has a pivotal role on balancing the antenna current. The study of the miniaturization process proved that it affects directly the gain, bandwidth, and efficiency. The antenna efficiency and gain were improved using the truncated ground plane. This antenna has a measured gain of -0.86 dBi and measured efficiency of 49.7%, making it one of the efficient and high gain small antennas. The 3D dipole antenna was designed using a novel method for efficiently exploiting the available volume. This method consists of fabricating the dipole on a cube configuration with opening up the internal volume for other uses. This antenna was tested, and it was found that this antenna has good radiation characteristics according to its occupied volume. Ka of this antenna is 0.55, its measured gain is 1.69 dBi with 64.2% measured efficiency. Therefore, this design is very promising in low-power sensing applications. A Wheeler Cap was designed for measuring the efficiency and the 3-antenna method was used for measuring the designed antennas gain.