In all energy systems, the parameters necessary to calculate power are the same in functionality: an effort or force needed to create a movement in an object and a flow or rate at which the object moves. Therefore, the power equation can generalized as a function of these two parameters: effort and flow, P = effort * flow. Analyzing various power transfer media this is true for at least three regimes: electrical, mechanical and hydraulic but not for magnetic. This implies that the conventional magnetic system model (the reluctance model) requires modifications in order to be consistent with other energy system models. Even further, performing a comprehensive comparison among the systems, each system's model includes an effort quantity, a flow quantity and three passive elements used to establish the amount of energy that is stored or dissipated as heat. After evaluating each one of them, it was clear that the conventional magnetic model did not follow the same pattern: the reluctance, as analogous to the electric resistance, should be a dissipative element instead it is an energy storage element. Furthermore, the two other elements are not defined. This difference has initiated a reevaluation of the conventional magnetic model. In this dissertation the fundamentals on electromagnetism and magnetic materials that supports the modifications proposed to the magnetic model are presented. Conceptual tests to a case study system were performed in order to figure out the network configuration that better represents its real behavior. Furthermore, analytical and numerical techniques were developed in MATLAB and Simulink in order to validate our model. Finally, the feasibility of a novel concept denominated magnetic transmission line was developed. This concept was introduced as an alternative to transmit power. In this case, the media of transport was a magnetic material. The richness of the power-invariant magnetic model and its similarities with the electric model enlighten us to apply concepts and calculation techniques new to the magnetic regime but common to the electric one, such as, net power, power factor, and efficiency, in order to evaluate the power transmission capabilities of a magnetic system. The fundamental contribution of this research is that it presents an alternative to model magnetic systems using a simpler, more physical approach. As the model is standard to other systems' models it allows the engineer or researcher to perform analogies among systems in order to gather insights and a clearer understanding of magnetic systems which up to now has been very complex and theoretical.

Definir los parámetros de polarización de la luz procedente de una muestra aporta una mayor información sobre las propiedades de ésta que la simple medida de la intensidad luminosa difundida. Cuando un haz luminoso sufre una perturbación debida a cualquier interacción con un medio, los campos electromagnéticos del haz incidente y el del haz emergente, expresados en términos de los parámetros de Stokes, pueden ser relacionados mediante la denominada matriz de Mueller. En este aspecto, el conocer la evolución de los parámetros de dicha matriz del sistema, nos permitiría definir cómo se comporta éste frente a la luz incidente. Para tal objetivo, se ha puesto a punto un polarímetro dinámico basado en técnicas de Transformada de Fourier, que permite determinar con una sola medida los 16 elementos de la matriz de Mueller. Ésta nos mostrará los cambios sufridos por la polarización del haz incidente debido a su interacción con una muestra problema.Aplicando el método de Descomposición Polar, se puede ver que cualquier sistema puro, con matriz de Mueller M, responde a la siguiente relación: M=R*D, donde R y D simbolizan las matrices de Mueller de un medio Retardador ideal y de un medio Diatenuador ideal, respectivamente. En una versión extendida de éste teorema, teniendo en cuenta que no todos los medios son ideales, sino que hay medios en los que aparecen efectos de despolarización, la descomposición de la matriz de Mueller daría lugar a: M=Z*R*D, tomando Z como la matriz de Mueller de un sistema despolarizante. De esta forma, utilizando algebra matricial, podemos descomponer la matriz de un sistema problema, en matrices de menor complejidad, con un estricto sentido físico.Partiendo de éstos resultados teóricos, y por medio del uso del polarímetro dinámico para la caracterización polarimétrica de los sistemas, se han analizado muestras de diversos tipos: superficies planas microestructuradas, para evaluar el efecto de la composición, tamaño e interacción; suspensiones de micropartículas y nanopartículas en coloide, para caracterizar su tamaño y composición; y sustancias quirales en medios turbios (en éste aspecto, recientemente ha sido demostrada la validez de éste método para el análisis in situ de tejidos biológicos). Asimismo, se han caracterizado componentes ópticos y polarimétricos por transmisión y reflexión, demostrando la validez del método. Finalmente se han llevado a cabo simulaciones computacionales a fin de estudiar patrones de comportamiento en sistemas complejos por medio del método de Descomposición Polar. / Polarization parameters of light scattered from a sample give more information about its properties than the light scattering intensity measurement. When a light beam interacts with an object or a medium, the electromagnetic fields of the incident and the emerging beam, both expressed in terms of Stokes parameters, can be related by the so-called Mueller matrix. In this respect, the matrix elements are associated to the physical system and define its behaviour. For the analysis of real systems, Mueller matrix must be experimentally obtained. For this purpose, a dynamic polarimeter (DRCP or Dual Rotating Compensator Polarimeter) based on Fourier Transform techniques has been developed, which allow us to determine the 16 elements of the Mueller matrix in a single cycle of measurements.Applying an algebraic tool, as the Polar Decomposition method (PD), we can see that any Mueller matrix corresponding to a pure system satisfies: M = R * D, where R and D are the Mueller matrices of an ideal Retarder and a Diattenuator, respectively. In an extended version of PD, taking into account that not all matrices are ideal, but there are systems in which depolarization effects occur, the decomposition of the Mueller matrix would lead to: M = Z * R * D, with Z representing the depolarization. Thus, using matrix algebra, we can decompose the matrix of a system, in a product of matrices with a strict physical sense.Based on these theoretical results and by using a polarimetric characterization of systems (through PDRC measurements), we have analyzed samples of different types: flat microstructured surfaces to evaluate the effect of the composition, size and interaction; suspensions of microparticles or nanoparticles to characterize their size and composition; chiral substances in turbid media (in this aspect has recently been demonstrated the validity of this method for the analysis of biological tissues "in situ"); characterization and study of polarimetric optics in transmission and reflection, demonstrating the validity of the method. Finally, we have carried out computer simulations to explore patterns in complex systems using PD.

A helicon plasma source is a device that can efficiently ionize a gas to create high density, low temperature plasma. There is growing interest in utilizing a helicon plasma source in propulsive applications, but it is not yet known if the helicon plasma source is able to function as both an ion source and ion accelerator, or whether an additional ion acceleration stage is required. In order to evaluate the capability of the helicon source to accelerate ions, the acceleration and ionization processes must be decoupled and examined individually. To accomplish this, a case study of two helicon thruster configurations is conducted. The first is an electrodeless design that consists of the helicon plasma source alone, and the second is a helicon ion engine that combines the helicon plasma source with electrostatic grids used in ion engines. The gridded configuration separates the ionization and ion acceleration mechanisms and allows for individual evaluation not only of ion acceleration, but also of the components of total power expenditure and the ion production cost. In this study, both thruster configurations are fabricated and experimentally characterized. The metrics used to evaluate ion acceleration are ion energy, ion beam current, and the plume divergence half-angle, as these capture the magnitude of ion acceleration and the bulk trajectory of the accelerated ions. The electrode-less thruster is further studied by measuring the plasma potential, ion number density, and electron temperature inside the discharge chamber and in the plume up to 60 cm downstream and 45 cm radially outward. The two configurations are tested across several operating parameter ranges: 343-600 W RF power, 50-450 G magnetic field strength, 1.0-4.5 mg/s argon flow rate, and the gridded configuration is tested over a 100-600 V discharge voltage range. Both configurations have thrust and efficiency below that of contemporary thrusters of similar power, but are distinct in terms of ion acceleration capability. The gridded configuration produces a 65-120 mA ion beam with energies in the hundreds of volts that is relatively collimated. The operating conditions also demonstrate clear control over the performance metrics. In contrast, the electrodeless configuration generally produces a beam current less than 20 mA at energies between 20-40 V in a very divergent plume. The ion energy is set by the change in plasma potential from inside the device to the plume. The divergence ion trajectories are caused by regions of high plasma potential that create radial electric fields.. Furthermore, the operating conditions have limited control of the resulting performance metrics. The estimated ion production cost of the helicon ranged between 132-212 eV/ion for argon, the lower bound of which is comparable to the 157 eV/ion in contemporary DC discharges. The primary power expenditures are due to ion loss to the walls and high electron temperature leading to energy loss at the plasma sheaths. The conclusion from this work is that the helicon plasma source is unsuitable as a single-stage thruster system. However, it is an efficient ion source and, if paired with an additional ion acceleration stage, can be integrated into an effective propulsion system.

This document contains a proposal for the creation of a simulator that can accurately model the interaction of electromagnetic (EM) and semiconductor effects for modern wireless devices including nonlinear and/or active devices. The proposed simulator couples the balanced semiconductor equations (charge, momentum, kinetic energy) with a FDTD full-wave Yee-based electromagnetic (EM) simulator. The resultant CAD tool is able to model the response of one semiconductor device to both small signal and DC bias based on the process parameters (material, charge distribution and doping) without any a-priori knowledge of the device performance characteristics, thus making it extremely useful in modeling and integrating novel devices in RF and Wireless topologies. As a proof of concept an n+--i--n+ diode will be simulated. In the future, more complicated structures, such as MODFETs, will be modeled as well.

I review the construction of Hertz potentials in vector calculus starting from Maxwell's equations. From here, I lay the minimal foundations of differential geometry to construct Hertz potentials for a general (spatially compact) Lorentzian manifold with or without boundary. In this general framework, I discuss "scalar" Hertz potentials as they apply to the vector calculus situation, and I consider their possible generalization, showing which procedures used by previous authors fail to generalize and which succeed, if any. I give specific examples, including the standard at coordinate systems and an example of a non-flat metric, specifically a spherically symmetric black hole. Additionally, I generalize the introduction of gauge terms, and I present techniques for introducing gauge terms of arbitrary order. Finally, I give a treatment of one application of Hertz potentials, namely calculating electromagnetic Casimir interactions for a couple of systems.

This thesis concentrates on the algorithmic aspects of Method of Moments (MoM) and Locally Corrected Nyström (LCN) numerical methods in electromagnetics. The data dependency in each step of the algorithm is analyzed to implement a parallel version that can harness the powerful processing power of a General Purpose Graphics Processing Unit (GPGPU). The GPGPU programming model provided by NVIDIA's Compute Unified Device Architecture (CUDA) is described to learn the software tools at hand enabling us to implement C code on the GPGPU. Various optimizations such as the partial update at every iteration, inter-block synchronization and using shared memory enable us to achieve an overall speedup of approximately 10. The study also brings out the strengths and weaknesses in implementing different methods such as Crout's LU decomposition and triangular matrix inversion on a GPGPU architecture. The results suggest future directions of study in different algorithms and their effectiveness on a parallel processor environment. The performance data collected show how different features of the GPGPU architecture can be enhanced to yield higher speedup.

A quadrature phase shift keying (QPSK) retrodirective array phase modulator (RAPM) was designed and fabricated to characterize its backscatter signal constellation when placed near objects with varying conductivities and relative permittivities. The signal constellations produced when the RAPM was placed near objects were compared to a constellation in free space to determine relative magnitude and phase changes. When conductors and high permittivity dielectrics were placed close behind the RAPM, constellation points were found to shrink in magnitude by up to twenty percent and shift in phase by up to eight degrees. When conductors were placed between the RAPM and an interrogator, the signal constellation was found to collapse, shrinking by up to 95.6 percent. For materials similar to free space, minimal constellation shrinkage resulted, but signal constellation rotation by up to 68 degrees occurred. The power consumption of a RAPM was also characterized and found to decrease as the number of bits per symbol increased. This result demonstrates that in comparison to conventional backscatter tags, which implement one bit per symbol, the RAPM can implement a greater number of bits per symbol, reduce its power consumption, and increase its range in a passive backscatter communication system. To characterize the beamwidth of the RAPM's retrodirective array, a radar cross section (RCS) measurement of the RAPM was performed over a scan angle range of -90 to +90 degrees. The structural component generated by the RAPM's patch antenna ground plane was found to dominate the antenna mode of the retrodirective array. As a result, a novel homodyne receiver based RCS measurement was performed to filter out the structural RCS component and measure the pure antenna mode of the RAPM.

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

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