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Este trabalho discute o efeito do tamanho de grão, frequência de excitação e resistividade elétrica nas perdas magnéticas, destacando-se a perda anômala. Também é proposto um método de sobreposição de histereses onde é revelada a região de ocorrência da perda anômala durante o ciclo de magnetização e desmagnetização, e posteriormente a curva de histerese da perda anômala é construída. Para tal, três ligas de aço de grão não orientado, com teor de silício de 2,05%, 2,45%, 3,3%, foram tratadas termicamente para aumento do tamanho de grão por crescimento. Cada liga foi tratada sobre a mesma sequência de temperatura, em recozimento contínuo. Os tamanhos de grão das amostras foram medidos pelo método de interceptos. A caracterização das propriedades magnéticas foi realizada por meio do quadro de Epstein. As amostras, no total de 21 conjuntos, foram ensaiadas em regime de frequência de 50, 60, 100, 150 e 200 Hz e regime quase estático (5mHz), ambos a 1 e 1,5 T. Possibilitando desta forma, a construção da histerese da perda histerética e total. Por meio dos resultados da perda total, histerética e parasita, a perda anômala pode ser calculada. Os resultados mostraram o comportamento da perda anômala (Pa) em função do tamanho de grão (l) do tipo Pa ∝ l0,34 e em frequência (f) a relação de Pa ∝ f1,65. A respeito do comportamento da perda anômala em função da resistividade elétrica (ρ), os resultados encontrados são inconclusivos. Constatou-se empiricamente que, o tamanho de grão ótimo é função da frequência e da indução. A partir de tratamento matemático, a histerese da perda parasita mais histerética, foi construída e sobreposta à histerese da perda total. Os espaços vazios entre as curvas corresponder à perda anômala. É visto que a perda anômala ocorre em três regiões distintas da curva de histerese. Tais regiões podem supostamente ser associadas à fenômenos de dissipação de energia como; movimento de parede de domínio, nucleação de domínios e aniquilação de domínio. Como as histereses da perda total, histerética e parasita possuem a mesma indução, a histerese da perda anômala pode ser construída. O campo associado à perda anômala foi obtido como resultado da soma entre campo histerético mais parasita menos o campo magnético da perda total. / This paper discusses about the effect of grain size, excitation frequency and electrical resistivity in magnetic losses, especially the anomalous loss. Also is proposed a method of overlapping hysteresis where the region of occurrence of the anomalous loss during magnetization and demagnetization cycle is disclosed, and thereafter the hysteresis curve of anomalous loss is constructed. For this purpose, three non-oriented steel alloys, with silicon content of 2.05%, 2.45%, 3.3%, were heat treated to increase the grain size by grain growth. Each alloy was treated in the same sequence of temperature in continuous annealing. The grain sizes of the samples were measured by an intercept method. Characterization of magnetic properties was performed using the Epstein frame. The samples, in total 21 sets, were tested under a frequency of 50, 60, 100, 150 and 200 Hz and quasi-static regime (5mHz), both at 1 and 1.5 T. Thus allowing the construction of the hysteresis of quasi-static and total loss. Through the results of the total loss, quasi-static loss and parasite loss, the anomalous loss can be calculated. The results show the behavior of the anomalous loss (Pa) as a function of grain size (l) as Pa ∝ l0.34 and frequency (f) the relationship of Pa ∝ f1.65. Regarding the behavior of the anomalous loss due to resistivity (ρ), the results are inconclusive. It was found empirically that the optimum grain size is a function of frequency and induction. From a mathematical treatment, the hysteresis of parasite loss plus quasi-static loss was constructed and overlapped to the hysteresis of total loss. The areas between the curves correspond to anomalous loss. It can be seen that anomalous loss occurs in three distinct regions of the hysteresis curve. Such regions may be associated with energy dissipation phenomena, such as: domain wall motion, nucleation and annihilation of domain. Since the hysteresis of total loss, quasi-static loss and parasite loss have the same induction, anomalous hysteresis loss can be constructed. The field associated with anomalous loss was obtained as a result of the sum of quasi-static field plus parasite field minus the magnetic field of the total loss.

A Paul trap mass spectrometer has a three-electrode geometry mass analyzer consisting of two identical end cap electrodes and a ring electrode. Traditionally, the two end cap electrodes are electrically grounded and an RF potential is applied to the central ring electrode to generate the "trapping field". Ions of the analyte sample are formed in situ by electron bombardment and mass analysis of the fragment ions is performed by mass selectively destabilizing the ions from the trap. The inhornogeneities present in the trapping field (introduced either by misalignment of the trap geometry or by applying a dipolar auxiliary excitation across the end cap electrodes) give rise to various interesting phenomena including, resonance ejection of the trapped ions This thesis is concerned with taking a look into the experimental aspects associated with resonance ejection of ions caused by the dipolar excitation Additionally, u also reports the work undertaken to develop necessary instrumentation for resonant excitation experiments and my contribution to operational>zc the Paul trap mass spectrometer fabricated in the laboratory. The thesis is divided into 5 chapters. Chapter 1 is an introductory chapter. After discussing the conditions for stability of the trapped ions, it goes on to present a brief survey of a variety of applications in literature, which have used resonant excitation. Towards the end, the motivation of the present effort and the scope of work in the thesis have been spelt out. This includes (a) redesign of the ion detector electronics, (b) design of an auxiliary excitation generator, and (c) studies on resonance ejection. Chapter 2 outlines the design considerations, circuit description and fabrication details for the ion detector electronics. The circuits presented in this chapter include (a) electrometer amplifier and (b) -3 kV DC supply for the electron multiplier detector. The electrometer amplifier amplifies the ion current signal from the electron multiplier detector and it needs to have a high input impedance and a high slew rate. The electron multiplier detector requires -3 kV DC power supply for operation. The -3 kV DC power supply is required to have a regulated output voltage with low ripple in the output. Chapter 3 presents the design considerations, circuit description and fabrication details for the auxiliary excitation generator. The auxiliary excitation generator is a three channel DDS (Direct Digital Synthesis) oscillator with independent control of frequency amplitude, and phase of the output signal. Chapter 3 also discusses the micro controller based control sub-system that allows the user to set above mentioned output parameters. The control sub-system provides a user-friendly keyboard interface and 2-line alphanumeric LCD display per channel. It also provides various bus interfaces (such as I2C and SPI) to interface with DDS oscillator ICs, amplitude control DAC, and LCD displays. The chapter then goes on to describe the implementation details of the software written for the control sub-system. The hardware design is simplified by using a micro controller as heart of the control sub-system and employing the software to handle the complex functions. As an example, the design of the keyboard interface is simplified by directly connecting a matrix keyboard to the input/output port of the micro controller. The software is used to scan the keyboard, detect key press and find out the key pressed. Nonetheless, in order to meet specific performance required for the present work, the software needs to have a sense of time, be portable and scalable. Details of the "layered" architecture adopted by as to meet these specific requirements, the lower level "driver" functions implemented for various interfaces of the control sub-system, and the higher level or the "application" software, are described. The application software uses the driver functions to accomplish various tasks required to be executed by the control sub-system. Finally, the chapter presents the design consideration and fabrication details of the coupling transformer used to couple the output of the auxiliary excitation generator to the Paul trap Chapter 4 describes the resonant excitation experiments performed as part of the present work. First of all the chapter presents the improvement in the performance of the Paul trap mass spectrometer as a result of redesigned ion detector electronics It is seen that the resolution is improved significantly due to the improved response time of the electrometer amplifier. The chapter then describes the effect of the resonant excitation on the ions and also that the frequency of the applied auxiliary excitation should be between 500 kHz to 125 kHz. Next, a number of mass spectra for different frequencies of the applied auxiliary excitation are presented. These mass spectra indicate that the resonant ejection sets in for lower masses even at lower amplitude of the auxiliary excitation where as higher amplitude is required for the resonant ejection of the higher masses. It is seen that the resonant excitation of ions improves resolution of the mass spectrum. Moreover, the auxiliary excitation results in ejection of the ions at lower amplitude of the RF voltage and thus allows extending the mass range of the mass spectrometer. We present the mass spectrum of CCI4 which is not possible to normally record in our instrument. We also present results intended to understand the relation between frequency and amplitude of the auxiliary excitation on the mass spectra of benzene. Finally, results of an interesting experiment are presented which indicates the presence of the non-linear resonance points in the Paul trap. Chapter 5 presents the concluding remarks. References cited in the thesis are attached in their alphabetical order at the end of the thesis.

Este trabalho discute o efeito do tamanho de grão, frequência de excitação e resistividade elétrica nas perdas magnéticas, destacando-se a perda anômala. Também é proposto um método de sobreposição de histereses onde é revelada a região de ocorrência da perda anômala durante o ciclo de magnetização e desmagnetização, e posteriormente a curva de histerese da perda anômala é construída. Para tal, três ligas de aço de grão não orientado, com teor de silício de 2,05%, 2,45%, 3,3%, foram tratadas termicamente para aumento do tamanho de grão por crescimento. Cada liga foi tratada sobre a mesma sequência de temperatura, em recozimento contínuo. Os tamanhos de grão das amostras foram medidos pelo método de interceptos. A caracterização das propriedades magnéticas foi realizada por meio do quadro de Epstein. As amostras, no total de 21 conjuntos, foram ensaiadas em regime de frequência de 50, 60, 100, 150 e 200 Hz e regime quase estático (5mHz), ambos a 1 e 1,5 T. Possibilitando desta forma, a construção da histerese da perda histerética e total. Por meio dos resultados da perda total, histerética e parasita, a perda anômala pode ser calculada. Os resultados mostraram o comportamento da perda anômala (Pa) em função do tamanho de grão (l) do tipo Pa ∝ l0,34 e em frequência (f) a relação de Pa ∝ f1,65. A respeito do comportamento da perda anômala em função da resistividade elétrica (ρ), os resultados encontrados são inconclusivos. Constatou-se empiricamente que, o tamanho de grão ótimo é função da frequência e da indução. A partir de tratamento matemático, a histerese da perda parasita mais histerética, foi construída e sobreposta à histerese da perda total. Os espaços vazios entre as curvas corresponder à perda anômala. É visto que a perda anômala ocorre em três regiões distintas da curva de histerese. Tais regiões podem supostamente ser associadas à fenômenos de dissipação de energia como; movimento de parede de domínio, nucleação de domínios e aniquilação de domínio. Como as histereses da perda total, histerética e parasita possuem a mesma indução, a histerese da perda anômala pode ser construída. O campo associado à perda anômala foi obtido como resultado da soma entre campo histerético mais parasita menos o campo magnético da perda total. / This paper discusses about the effect of grain size, excitation frequency and electrical resistivity in magnetic losses, especially the anomalous loss. Also is proposed a method of overlapping hysteresis where the region of occurrence of the anomalous loss during magnetization and demagnetization cycle is disclosed, and thereafter the hysteresis curve of anomalous loss is constructed. For this purpose, three non-oriented steel alloys, with silicon content of 2.05%, 2.45%, 3.3%, were heat treated to increase the grain size by grain growth. Each alloy was treated in the same sequence of temperature in continuous annealing. The grain sizes of the samples were measured by an intercept method. Characterization of magnetic properties was performed using the Epstein frame. The samples, in total 21 sets, were tested under a frequency of 50, 60, 100, 150 and 200 Hz and quasi-static regime (5mHz), both at 1 and 1.5 T. Thus allowing the construction of the hysteresis of quasi-static and total loss. Through the results of the total loss, quasi-static loss and parasite loss, the anomalous loss can be calculated. The results show the behavior of the anomalous loss (Pa) as a function of grain size (l) as Pa ∝ l0.34 and frequency (f) the relationship of Pa ∝ f1.65. Regarding the behavior of the anomalous loss due to resistivity (ρ), the results are inconclusive. It was found empirically that the optimum grain size is a function of frequency and induction. From a mathematical treatment, the hysteresis of parasite loss plus quasi-static loss was constructed and overlapped to the hysteresis of total loss. The areas between the curves correspond to anomalous loss. It can be seen that anomalous loss occurs in three distinct regions of the hysteresis curve. Such regions may be associated with energy dissipation phenomena, such as: domain wall motion, nucleation and annihilation of domain. Since the hysteresis of total loss, quasi-static loss and parasite loss have the same induction, anomalous hysteresis loss can be constructed. The field associated with anomalous loss was obtained as a result of the sum of quasi-static field plus parasite field minus the magnetic field of the total loss.

Im Bereich der industriellen Metallurgie und Kristallzüchtung treten bei zahlreichen Anwendungen, wo magnetische Wechselfelder zur induktiven Beeinflussung von leitfähigen Werkstoffen eingesetzt werden, auch Strömungen mit freier Oberfläche auf. Das Anwendungsspektrum reicht dabei vom einfachen Aufschmelzen eines Metalls in einem offenen Tiegel bis hin zur vollständigen Levitation. Auch der sogenannte RGS-Prozess, ein substratbasiertes Kristallisationsverfahren zur Herstellung siliziumbasierter Dünnschichtmaterialien, ist dafür ein Beispiel. Um bei solchen Prozessen die Interaktion von Magnetfeld und Strömung zu untersuchen, ist die numerische Simulationen ein wertvolles Hilfsmittel. Für beliebige dreidimensionale Probleme werden entsprechende Berechnungen bisher durch eine externe Kopplung kommerzieller Programme realisiert, die für Magnetfeld und Strömung jeweils unterschiedliche numerische Techniken nutzen. Diese Vorgehensweise ist jedoch im Allgemeinen mit unnötigem Rechenaufwand verbunden. In dieser Arbeit wird ein neu entwickelter Methodenapparat auf Basis der FVM vorgestellt, mit welchem sich diese Art von Berechnungen effizient durchführen lassen. Mit der Implementierung dieser Methoden in foam-extend, einer erweiterten Version der quelloffenen Software OpenFOAM, ist daraus ein leistungsfähiges Werkzeug in Form einer freien Simulationsplattform entstanden, welches sich durch einen modularen Aufbau leicht erweitern lässt. Mit dieser Plattform wurden in foam-extend auch erstmalig dreidimensionale Induktionsprozesse im Frequenzraum gelöst.