Energy-Scale Systematics at the KATRIN Main Spectrometer

This thesis deals with the systematic uncertainties related to the high-precision energy filtering of electrons at the Karlsruhe Tritium Neutrino (KATRIN) experiment. A high degree of understanding of corresponding effects is essential to reach the targeted ?-mass sensitivity of 200 meV (90% C.L.)

Measurement Techniques for Impulse Puncture Testing in Air

Impulse voltage puncture testing (IPT) in air, as per IEC-61211, is used to assess the withstand strength of class B ceramic/glass insulators primarily against very fast front voltage transients (VFFTs) in power systems. This method uses short HV impulses of front times as low as 100 ns, therefore, adequate execution and reproducible results are not ensured because no standard impulse shape exists for VFFTs, no calibration service exists for such systems below 0.84 μs and the measurement system gets affected by many factors e.g. proximity effects, interferences, clearances and stray capacitances and inductances. This study focuses on investigating the testing practices and measurement techniques, for IPT in air as per IEC-61211, to find suitable testing methodologies. Based on the results of a research survey done to know practices and capabilities of HV labs in this regard, testing was performed on a cap and pin insulator, mounted on a metal plate using ball-socket and stressed with steep front HV impulses. A 500 mm wide copper sheet was used for grounding. Measurement system comprised of a fast resistive divider, a 50 tri-axial cable, a 10:1 attenuator of 50 input resistance and a 200 MHz, 8 bit, 2.5G S/s digitizer. The dependency of results on factors like divider-insulator distances, extra cable shielding, various target test voltages, HV damping resistor and different generation circuits was studied. No puncture of insulation happened. The divider showed high overshoot in step response and low bandwidth in impulse results. Due to these reasons, along with its damage during testing, a new divider design is proposed for 500-600 kV that is modular in structure and aims to solve the problem of low bandwidth by allowing its HV arm to be placed in direct contact with insulator. A novel algorithm is also proposed to analyse the linearity of front chopped impulses. It also revealed that following exact definition of Tc in IEC-60060-1 could result in it’s wrong determination from measurement software

Modeling and visualizing networked multi-core embedded software energy consumption

In this report we present a network-level multi-core energy model and a software development process workflow that allows software developers to estimate the energy consumption of multi-core embedded programs. This work focuses on a high performance, cache-less and timing predictable embedded processor architecture, XS1. Prior modelling work is improved to increase accuracy, then extended to be parametric with respect to voltage and frequency scaling (VFS) and then integrated into a larger scale model of a network of interconnected cores. The modelling is supported by enhancements to an open source instruction set simulator to provide the first network timing aware simulations of the target architecture. Simulation based modelling techniques are combined with methods of results presentation to demonstrate how such work can be integrated into a software developer's workflow, enabling the developer to make informed, energy aware coding decisions. A set of single-, multi-threaded and multi-core benchmarks are used to exercise and evaluate the models and provide use case examples for how results can be presented and interpreted. The models all yield accuracy within an average +/-5 % error margin

Printed Electronics Power Supply for IoT Systems

CeNTI - Center for Nanotechnology and Smart Materials is an institute of R&D located in Famalicão. The main goal of the institute is to promote activities of research, Technological Development, Innovation and Engineering with special focus in smart materials and systems. The Internet Of Things is the concept by which multiple devices, are connected and performing activities with each other, such as communication and processing, without human interference. The development of multiple technologies such Artificial Intelligence, Machine Learning, Smart homes, smart devices has accelerated the convergence of all into networks. These networks at the edge of the system possess devices that are meant to make the connection between cyber environments and physical ones. This type of devices are often referred to as Edge devices. Devices like these are most often low power devices used to sense aspects of the physical system and their dimension might be a defining factor to decide if such system is adequate to its function. In sensors the most common forms of power supplies are batteries, mains electricity with a transformer for voltage division and isolation or a combination of both. With the increasing need for miniaturization and technological means to achieve it, the investigation of novel forms becomes more and more relevant. The main objective of this thesis is to investigate the use of printed electronics and in particular printed inductors, to attain an efficient and safe power supply adequate for human handling while aiming to reduce the final volume of the system. The approach intents to use the traditional Transformerless Power Supply circuit configuration using capacitors to drop the mains voltage. Such goal is to prevent undesired power expenditure caused by the introduction of resistances. Besides the voltage drop and rectification the other major concern of the system is the safety of the human operator that may touch the device. Voltage dropping and rectification of grid power is an extremely dangerous circuit configuration due to different ground references and creates an electrocution hazard to both living beings and devices connected to it. The way to circumvent the danger is to introduce galvanic isolation. The system proposed in this project physically separates the output of the system from the input with energy being transferred magnetically. For that purpose, printed inductors are stacked to achieve a planar air-core transformer. The system aims contributes to the continued minimizing of Edge devices that will become progressively more present in everyday life.In recent times, connected devices are becoming increasingly more common. Such devices usually referred to as IoT (Internet of Things), are converging to ever small builds. This document aims to deepen the progress in the field of miniaturization of such devices. To achieve this goal a power supply is designed. The project intents to offer an alternative to common power supplies by making use of printed inductors. Such components intent to replace the traditional transformer by suppling a reduced volume alternative. An investigation into these inductors is conducted and an implementation of its use is presented. The investigation led to conclude that the inductors may be used to provide isolation but further improvements into the fabrication process are required. Due to the current fabrication process involving impure silver as the conductor the resulting coils have a resistance excessively high. This creates difficulties in magnetic field creation as well as introducing a great level of losses. To solve this problem the presented implementation uses high frequency switching to allows for better results in the receiver side of the system

Integrated MEMS-Based Phase Shifters

Multilayer microwave circuit processing technology is essential in developing more compact radio frequency (RF) electronically scanned arrays (ESAs) for next generation radar systems. ESAs are typically realized using the hybrid connection of four discrete components: RF manifold, phase shifters or Butler matrices, antennas and T/R modules. The hybrid connection of these components increases the system size, packaging cost and introduces parasitic effects that lead to higher losses. In order to eliminate these drawbacks, there is a need to integrate these components on the same substrate, forming a monolithic phased array. RF MEMS technology enables the monolithic integration of the ESA components into one highly integrated multifunctional module, thereby enhancing ESA designs by significantly reducing size, fabrication cost and interconnection losses. A novel capacitive dual-warped beam shunt MEMS switch is presented that utilizes warped beams to enhance its RF performance. This switch exhibits an off-to-on capacitive ratio of almost 170, isolation better than 40dB, switching speeds as low as 6μs without the need for thin dielectrics or high dielectric constant materials. These MEMS switches are implemented into single pole three throw (SP3T) and single pole four throw (SP4T) configurations. A novel 3-bit finite ground coplanar waveguide switched delay line MEMS phase shifter is developed with four cascaded SP3T dual-warped beam capacitive switches to achieve low-loss performance and simplify ESA design. The fabricated prototype unit exhibits an insertion loss of 2.5∓0.2dB with a phase error of ∓6°. Moreover, a compact 4 x 4 Butler matrix switchable with the use of a MEMS SP4T switch is investigated as an alternative passive beamforming method. The overall beam-switching network is monolithically integrated within a real-estate area of 0.49cm2. This technique provides a unique approach to fabricate the entire beamforming network monolithically. An 8-mask fabrication process is developed that monolithically integrates the MEMS phase shifter and RF combining network on one substrate. The wafer-scale integrated ESA prototype unit has an area of 2.2cm2. It serves as the basic building block to construct larger scanning array modules and introduces a new level of functionality previously achieved only by the use of larger, heavier and expensive system

An Investigation into the Frequency Stability of Non-oven Controlled Crystal Oscillators

Temperature induced frequency deviation of quartz crystal oscillators can be reduced by tuning the oscillator to compensate for the thermal effects. A varactor tuned AT cut resonator is typically used to make a voltage controlled crystal oscillator. Compensation is then achieved by applying a "compensation voltage" to the varactor. The earliest compensation circuits comprised resistors and thermistors. Over the temperature range -40° C to +85°C resistive compensation circuits have achieved frequency stabilities of approximately + Ippm. Alternative analogue circuits have achieved frequency stability of < +0.5ppm. The research described in this thesis is an investigation of resistive networks in order to improve the levels of stability that can be achieved by this method of temperature compensation for crystal oscillators. The objective was to achieve a stability of < +0.5ppm over the temperature range -40°C to +85°C. Optimisation techniques have been employed to identify a new temperature compensation circuit. This new circuit uses an amplifier with temperature sensitive gain to modify thermistor characteristics and improve the compensation over the high part of the temperature range. Two forms of this circuit are presented. Computer simulation of this circuit has shown that it is capable of achieving frequency stability of < ±0.3ppm in an oscillator operating from a 4.5 V supply over the temperature range -40°C to +85°C

A 12b 100MSps Split Pipeline ADC with Open-Loop Residue Amplification

The design of a low-power 12-bit 100MSps pipeline analog-to-digital converter (ADC) with open-loop residue amplification using the novel Split-ADC architecture is described. The choice of a 12b 100MSps specification targets medical applications such as portable ultrasound. For a representative ADC such as the ADS5270, the figure of merit (FOM) is approximately 1pJ/step and the power dissipation is 113mW. The use of an open-loop residue amplifier resulted in a FOM of 0.571pJ/step and a power dissipation of 11.2mW

Capacitive current interruption with high voltage air-break disconnectors

Disconnectors are low-cost switching devices in high voltage electrical power supply systems that basically have an insulation function only. Nevertheless, they have a very limited capability to interrupt current (below one Ampere), e.g. from unloaded busbars or short overhead lines. The present study is a search for possibilities to increase the current interruption capability with auxiliary devices interacting with the switching arc. In this project the state of the art of disconnector switching is investigated and an inventory is presented of models of the free burning arc in air. A series of experiments were arranged at different laboratories. The switching arc and the interruption process are studied in detail through electrical and optical measurements during the switching process for a disconnector with (without) auxiliary devices under high voltage (300 kV) conditions. Three options for auxiliary devices were investigated: (i) arc cooling by forced air flow; (ii) fast interrupting by high-velocity opening contacts; (iii) reduction of arc energy by added resistive elements. Finally, a qualitative description is provided on the physical nature of the arc and how the evaluated methods affect the arc characteristics. All results are obtained by analysis of highresolution measurement of arc current (including all relevant transients), voltages across the disconnector and high-speed video observation. It was found that, depending on the current to be interrupted, the interruption process is governed by dielectric and/or thermal processes. In the dielectric regime, the interrupted current is low (roughly below 1A) and the switching arc is characterized by a high rate of repetition of interruptions and restrikes that only cease after a sufficient gap spacing has been reached. The restrikes interact severely with the circuitry in which the disconnector is embedded, exciting transients in current and voltage with frequencies up to the megahertz range. High overvoltages can be generated. Their magnitudes can be limited by a proper choice of the capacitance at supply side of the disconnector. The arc-circuit interaction has been studied and relevant processes have been modelled and verified by experiments in full-power test-circuits. In the thermal regime, the switching arc behaves less vehemently, interrupting and re-igniting basically occur at every power frequency current zero. Because of the presence of sufficient thermal energy in the switching gap along the arc path, the voltage to re-ignite the arc is limited, and the arc-circuit interaction is less pronounced. Though not producing very severe overvoltages, the arc duration is longer and the current may not be interrupted at every current zero crossing. The ultimate thermal regime is reached when the arc continues to exist after power frequency current zero without any appreciable voltage to re-ignite. This situation must be avoided because arcing goes on until a higher level breaker interrupts the current. Before this, the arc can reach far away from its roots and can greatly reduce insulation clearance. The main factors influencing the interruption performance are the level of current to be interrupted, the system voltage, the ratio of capacitances at both sides of the disconnector and the gap length. These factors influence the energy supplied to the arc upon re-strike. This energy extends the arcing time by lowering the breakdown voltage. It has been observed that the arc in its thermal mode always re-ignites in its former trajectory. Key to the interruption process is the reduction of breakdown voltage in this path, created by hot gases remaining from the former arc. The existing breakdown models are reviewed in order to understand the influence of high temperature air on the breakdown process. Based on the observed arc behaviour, various methods have been researched to increase the interruption capability. The most successful methods are those that remove the residual (partially) ionized air from the arc path. Experiments were carried out to demonstrate the effectiveness of air flow directed into the arc’s foot point. A substantial gain in interruption capability is demonstrated, but at the cost of generating re-ignition transients at a very rapid succession. Specifically, the experiments showed that 7.5 A could be interrupted successfully at 90 kVrms voltage with a shorter arcing duration (a factor of 0.5 was observed) than without air flow. With application of air flow, the frequency of re-ignitions occurring, and the breakdown voltage are much higher than without air flow. Another method, the assistance of an auxiliary switch able to produce a very fast opening, was also successful. Herein, the arc is forced mechanically into ambient cool air, thus avoiding accumulation of thermal energy in the arc path. Specifically, it can interrupt currents up to 7 A at 100 kVrms safely and 9 A at 90 kVrms in the experiments with arcing time only a few tens of milliseconds instead of a few seconds. The arc exhibits a "stiff" (linear) character instead of the "erratic" (randomly moving) arc mode with a disconnector alone. This method reduces the number of re-strikes. The possible influence of energy absorbing elements (resistors) is investigated through circuit modelling, supported by some laboratory experiments. Other methods, such as the application of series auxiliary interrupting elements (vacuum, SF6 interrupter and ablation assisted approaches) have been evaluated. From the practical point of view, the auxiliary fast-opening interrupter is recommended due to its economic, simple and effective merits. Other approaches have certain disadvantages. The method with air flow needs a complex construction in order to introduce the compressed air flow into the disconnector, and the hazard for nearby equipments from the overvoltages caused by the interruption is greater. The method of inserted resistor requires very expensive arrangement. Regarding the application of auxiliary interrupters, vacuum interrupters have to be applied in considerable numbers in series and SF6 interrupters have good performance but at very high cost. An ablation assisted approach seems less promising because the level of the interrupted current is too low to be effective

A Current-Mode Multi-Channel Integrating Analog-to-Digital Converter

Multi-channel analog to digital converters (ADCs) are required where signals from multiple sensors can be digitized. A lower power per channel for such systems is important in order that when the number of channels is increased the power does not increase drastically. Many applications require signals from current output sensors, such as photosensors and photodiodes to be digitized. Applications for these sensors include spectroscopy and imaging. The ability to digitize current signals without converting currents to voltages saves power, area, and the design time required to implement I-to-V converters. This work describes a novel and unique current-mode multi-channel integrating ADC which processes current signals from sensors and converts it to digital format. The ADC facilitates the processing of current analog signals without the use of transconductors. An attempt has been made also to incorporate voltage-mode techniques into the current-mode design so that the advantages of both techniques can be utilized to augment the performance of the system. Additionally since input signals are in the form of currents, the dynamic range of the ADC is less dependant on the supply voltage. A prototype 4-channel ADC design was fabricated in a 0.5-micron bulk CMOS process. The measurement results for a 10Ksps sampling rate include a DNL, which is less than 0.5 LSB, and a power consumption of less than 2mW per channel