Browsing by Subject "Pulse generators"
Now showing 1 - 12 of 12
Results Per Page
Sort Options
Item Advanced compulsator topologies and technologies(2002-05) Walls, William Alan; Driga, Mricea D.Increasing the compactness of compensated pulsed alternators (compulsators) has been an ongoing effort at since the mid-1980’s, when the U. S. Army interest in electric armaments began to emerge in a significant way. Much progress has been made from the early proof of concept machine built at UTCEM in the late 1970’s after its invention by Weldon, Driga, and Woodson. Today, the compulsator is the best approach for achieving compact energy storage and pulsed power generation for multi-MJ, multi-GW applications requiring voltages of up to 20 kV and discharge durations between 1 and 10 milliseconds. Electromagnetic railguns, coil launchers, and directed energy systems requiring high-power, high-energy pulsed-power in compact form are ideal candidate loads for compulsators. Since the initial validation of compulsator theory in the late 1970’s, a transition from iron-core to air-core magnetic circuits and the associated incorporation of composite materials for the rotor and self-excitation has provided substantial increases in both stored energy density and power density. While the advancement has been significant, further gains in compactness are possible by exploiting continued innovation in the topology of the machine, the mode in which it operates, and by developing new component technologies specifically for compulsator application. In addition, the use of this type of machine in very high voltage (>50 kV) pulsed power application, a concept not previously explored, is considered through the novel integration of resonant and cascaded transformer arrangements to boost the output voltage. In contributing to the continued compulsator performance improvement, this research effort has performed an in depth study of machine topologies and identified a new topology, the flywheel-compulsator. When combined with improvements in materials and switching technologies, this new machine configuration can improve energy and power density by factors of three and five, respectively, compared to the current state of the art. To allow rapid sizing of compulsator systems, a scaling algorithm was developed, validated against demonstrated machines and advanced designs, and used to design systems for advanced applications. Reduced to a set of linked spreadsheets, the scaling algorithms were also used to identify compulsator component technologies areas where improvements will provide the greatest overall performance impact. Another area of significant contribution to compulsator technology embodied in this research is the application of these machines to very high voltage systems. Two general concepts were conceived and developed. The first combines the energy storage and pulsed power generation of the compulsator with voltage increasing circuits, including both resonant and cascaded transformers. For compact high voltage systems, the concept of generating the high voltage directly within the compulsator was evaluated, and a high voltage compulsator using a helical winding was optimized for a specific set of requirements.Item Development of open ferromagnetic circuit pulsed power generator(Texas Tech University, 2001-12) Llambes, Juan Carlos HernandezThe Pulsed Power Laboratory of the Electrical and Computer Engineering Department at Texas Tech has developed an open ferromagnetic system of pulsed power generation. In order to design a high performance compact pulsed power generator system, a detailed understanding of the physics of magnetic properties is needed. The objective of this work was to establish the fundamentals of the generator. The fundamentals will be very useful to predict its behavior and to design a specific compact pulsed power generator system. We could divide them as follows: Determine the current and voltage pulses that could be produced by this technique. Determine the fundamentals and parameters needed to build a model. Estimate the ultimate current, voltage pulses and power that could be produced by the generator. Perform tests and calculations for a specific load that will be used in the application for which this generator is designed. Simulate and calculate the behavior of the model in the transient operation to predict the output pulses. Study and determine the magnet parameters as well as how they affect the model. By following these fundamental principles procedures can be obtained for single turn ultimate current pulses of 6 to 7 kA with velocities of 250 to300 m/s in the current mode, with a projectile 2.54 cm diameter and 1.9 cm in length. Special software (Coil Designer Simulator) was programmed to determine the different parameters of the loads and pulse generating coils used. This paper describes the necessary methods in designing these test circuits to obtain the device characteristics just explained.Item Explosively-driven helical magneto-cumulative generators(Texas Tech University, 2002-08) Holt, Thomas AllenExplosively-Driven Helical Magneto-Cumulative Generators (HMCGs) have a wide variety of applications in today's pulsed power field. Though widely used, the physics of the anomalous flux loss associated with such devices is still poorly understood. Presented within are several different geometries of HMCGs designed to provide insight to, and possibly explain the anomalous flux loss. An overview of common loss mechanisms is provided as a baseline for determining whether poor performance reflects the presence of the anomalous loss or other loss mechanisms which are avoidable when proper design procedures are followed. The work presented herein was solely funded by the Explosively-Driven Power Generation MURI program funded by the Director of Defense Research & Engineering (DDR&E) and managed by the Air Force Office of Scientific Research (AFOSR).Item Item Nonlinear magnetic switches for pulse generation(Texas Tech University, 1980-05) Black, Susan ENot availableItem Operation of the HERA Railgun Facility at Texas Tech(Texas Tech University, 1992-12) Day, Phillip MichaelThe HERA Railgun Facility contains a 2 meter long, small bore railgun. Projectiles are injected into the railgun by a light gas injector (LGI). The railgun is to be used as a research tool to help understand the physics behind "velocity saturation" in railguns. Over the past two years, the railgun's power supply, controls, timing, and diagnostics have been designed and built The theory behind the various components that make up the railgun are discussed. The results from each component are also discussed. Velocity data from different projectile configurations are given and discussed.Item Optimization of the source function in an electron-beam sustained discharge containing attaching gases(Texas Tech University, 1986-08) Reinking, Gregory FranklinIn pulsed power work, large amounts of stored energy are frequently required. This energy may be stored more efficiently with respect to volume and weight with inductive storage rather than capacitive storage. In order to effectively transfer inductively stored energy to a load, a fast opening switch is necessary. Of the many opening switch methods under study, the externally sustained diffuse discharge switch has several advantages. In electron-beam sustained discharges, electrons are generated by the high energy beam electrons and depleted through recombination and attachment. The use of attachers is necessary to achieve fast opening times. This project considers the two processes, electron generation and depletion, which affect the conductivity of gas discharge switches. The optimization of electron generation is experimentally investigated through the introduction of a low ionization (Penning) additive to the switching gas mixture. The process of electron depletion is investigated theoretically with Monte Carlo Code calculations. These calculations concentrate on the thermalization process of the Initial fast electrons and the interaction of the thermalizing electrons with the attachers used in the gas discharge. The presented results provide information that is required to select suitable gas mixtures to optimize the efficiency of diffuse discharge switches.Item Pulser design and performance for an electron beam gun(Texas Tech University, 1977-05) Wilson, Dale GNot availableItem Reflex-triode geometry of the virtual cathode oscillator(Texas Tech University, 2003-12) Lara, Matthew BAn eight-stage four-hundred kilovolt Marx generator, in connection with a 60 nanosecond pulse-forming line, is constructed and utilized as a pulsed source to power a triode version of the Virtual Cathode Oscillator (Vircator). Eight . I uF capacitors, charged to 50kV each, are switched in series by dry-air pressurized spark gaps. The energy from the bank charges a 23 ohm oil transmission line, breaking a peaking gap when the maximum voltage is reached, delivering a 60 ns-400kV pulse to the diode. The design of the "Reflex-Triode" geometry Vircator is based upon claims of high efficiency by Didenko et al.[l] A previously constructed TTU Vircator includes a unique E-beam source, the "brush" cathode; in which a circular array of pins is used as an explosive field emission source to produce relatively high beam currents. The anode consists of a round wire mesh through which the E-beam passes, generating a dense cloud of negative charge known as a "Virtual Cathode." This initial phase of testing is composed of basic operation of the entire system and baseline output power and efficiency measurements.Item Synthesis of Pulse Forming Networks for General Resistive Loads(Texas Tech University, 1979-05) Roark, Ricki MorrisNot Available.Item The design of a high power electron beam generator(Texas Tech University, 1989-08) Augsburger, Blake W.The object of this experiment is to study high power microwave breakdown across a dielectric window. In order to achieve this objective a microwave source is designed and constructed. This report discusses the design of a pulsed power system used to drive this microwave source. This experiment is funded by the AFOSR/AFWL. The experiment was named THOR, after the Norse God of lightning and thunder.Item The evaluation and measurement of the effect of fuse materials and masses on railgun performance(Texas Tech University, 1995-05) Tanner, Mark RichardThe HERA (High Energy Railgun Apparatus) railgun device at Texas Tech University has been used to investigate the effects of armature fuses on plasma armature railguns. The fuse mass (thickness) was varied for both copper and aluminum fuses over a range of 0.05 g to l.l5 g in a l cm round bore geometry. Armature velocity and velocity saturation effects were observed. While holding railgun current and total projectile mass constant the fuse mass and material were varied. This paper will present the findings from the research, including representative data on velocity versus fuse material and mass, and velocity saturation. The experimental setup and methods will also be described.