Browsing by Subject "Breakdown voltage"
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Item A new design concept for field distortion triggered spark gaps(Texas Tech University, 1986-12) Pashaie-Awal, BijanCommon field-distortion triggered spark gaps utilizing geometric field enhancement at sharp edges usually operate in a cascade mode via the trigger electrode. A new trigger concept is proposed allowing strong field enhancement and direct breakdown between the two main electrodes. A test device was designed to prove the feasibility of this concept. Experimental results on hold-off voltage and on delay and jitter dependent on percent breakdown voltage are presented. Best results achieved are a delay of 9 nanoseconds (ns) and a jitter of 2 ns at a self-breakdown voltage of 15 KV. The fields code ELF (Tetra Corporation, Albuquerque, NM) was used to verify the experimental results. An optimum location of the trigger electrode was calculated, and it matched the experimental data within a 5% accuracy. A full-scale field distribution graph was generated in both the triggered and the non-triggered cases, which are believed to represent the triggering action.Item An electron beam triggered spark gap(Texas Tech University, 1981-08) McDonald, Kenneth FoxThe triggering of a high-voltage gas-insulated spark gap by an electron (e) beam has been investigated. Rise times of approximately 2.5 ns with sub-nanosecond jitter (~0.2 ns) have been obtained for 3 cm gaps charged at voltages as low as 50 percent of the self-breakdown voltage (varied up to 0.5 MV). The switch delay (including the e-beam diode) was 52 ns. The triggering e-beam pulse has a duration of 15 ns and a 0-50 percent rise time of 1.5 ns. The e-beam current is 0.5 kA, and the electron energy can be varied in the range from 80 to 145 keV. The working media were N2, mixture of N2 and Ar, and N2 and SF6 at pressures of 1-3 atm. Voltage, current and jitter measurements have been made for a wide range of gap conditions and e-beam parameters. The effects of varying the e-beam cross-sectional area and the beam energy are discussed.Item An improved data collection and processing system(Texas Tech University, 1987-12) O'Hair, John RNot availableItem Arc current, voltage, and resistance in a high energy, gas-filled spark gap(Texas Tech University, 1985-05) Maas, Brian LaneA spark gap was designed and constructed to measure the time dependent arc resistance. The arc current was measured and the arc resistance calculated using the current and the other circuit parameters. Typical operating parameters were: unipolar pulse, 35 kV breakdown voltage, 30 kA peak current, and 1.15 kJ total energy per shot. The dissipated arc energy was calculated from the arc current and resistance and found to be between 4.5% and 10.5% of the total energy. Arc resistance vs time curves were obtained for all possible combinations of three electrode materials (304 Stainless Steel, ACF-IOQ Graphite, and 3w3 Copper-Tungsten), three gases (Air, N2, and SF6), and three gas pressures ( 1 , 2, and 3 atmospheres). Statistical analysis was performed on the resultant data. Essential results are: within the statistical and measurement errors, the resistance is independent of the electrode material. For each gas, R is approximately proportional to pd (pressure and gap distance). The constants of proportionality are (31 ± 7) mΩ/(cm bar) for air, (47 + 15) mΩ/(cm bar) for N2, and (76 ± 17) mΩ/(cm bar) for SF6.Item Breakdown characteristics of an isolated conducting object in a uniform electric field(Texas Tech University, 1986-12) Grothaus, Michael GlennNot availableItem Breakdown processes in laser triggered switching(Texas Tech University, 1983-05) Dougal, Roger AdelbertAn investigation of laser triggered switching using a 1.06 µ NdrYAG laser to trigger a uniform field gap filled with 800 Torr of N2 has been performed in the following triggering geometries: 1) Transverse not striking electrodes, 2) Coaxial not striking electrodes, 3) Coaxial striking target electrode, and 4) Coaxial striking recess in target electrode. Streak photography, time resolved spectroscopy, and current measurements reveal great differences in the breakdown processes for the various geometries. The major differences are attributable to laser field interaction with the incipient arc channel. All breakdown processes except types 2 and 3 look quite similar to an overvolted breakdown. Diagnostics of type 2 triggering have shown a laser assisted streamer propagating from the laser fireball to the opposite electrode. Streak photography shows the streamer precursor of the breakdown channel initially proceeds across the gap at a few times 10 cm/sec, but slows to about 2X10 cm/sec as it advances in the focal cone to regions of lower laser intensity. The laser interaction with the streamer produces a uniform, high conductivity channel which emits intense continuum light once ohmic heating raises the channel temperature. When delay is greater than the laser pulse length two distinct regions can be detected in the arc channel; one, laser assisted, showing the abrupt, uniform continuum luminosity, and the other not laser assisted, appearing much like a weakly overvolted breakdown process, exhibiting a glow discharge stage followed by thermalization proceeding from the ends of the glow region towards the middle at 10 cm/sec.Item Development of a 100 kilovolt two nanosecond risetime probe with DC response(Texas Tech University, 1986-08) Power, John FNot availableItem Electrical characteristics of thermally evaporated stearic acid films(Texas Tech University, 1984-08) Huang, Ching-hsingThe d.c. dielectric breakdown properties of thermally deposited thin films of stearic acid (CH3, (CH2)16 COOH) have been investigated. The voltage vs. time (V-t) and current vs. voltage (I-V) characteristics were studied on test capacitors consisting of aluminum-stearic acid-aluminum. The film thickness (d) dependence studies of the dc breakdown field of these capacitors have been carried out in the thickness range 200-2000A. Electric breakdown processes in thin film insulators are discussed. Interpretation of the results are greatly facilitated by using specimens which were self-healed to eliminate most of the weak spots in the films. The experimental results are analyzed in the light of Forlani and Minnaja’s theory of ionization avalanche breakdown. The destruction of the capacitor after the breakdown has been studied using an optical microscope at constant magnification. Various types of rupture patterns are observed as a result of dielectric breakdown of these insulating films.Item Electrode erosion measurements in a high energy spark gap(Texas Tech University, 1982-08) Donaldson, Anthony LyleNot availableItem Energy considerations in second breakdown(Texas Tech University, 1984-12) McMullen, Scott AllenNot availableItem Experimental investigations of subnanosecond gas breakdown(Texas Tech University, 2000-12) Short, Brent D.The recentiy developed concept of plasma limiters requires breakdown in gas with subnanosecond delays. If subnanosecond breakdown can be achieved in a transmission line or waveguide, most incoming power could be reflected, protecting any circuitry on the other side. This experiment consisted of a study of breakdown in gas using a needle tip to plane geometry with high voltage pulsers, ranging from 1 to 7.5 kV, with a typical risetime of 500 ps. The setup consists of a pulser feeding a 50 U transmission line to a needle-plane test gap inside a vacuum chamber, terminated in a 50Q load line. The needles used have a tip radius of less than 1|xm to produce a high electric field enhancement at the test gap. Measurements were taken from current and voltage sensors on the input transmission line, and the luminosity of discharge was measured with a photomultiplier tube. For voltages of 1.7 kV and below, a minimum breakdown delay of 12 ns was measured. At 15 kV, achieved with a 7.5 kV pulser with the voltage doubling at an open circuit at the test gap, subnanosecond breakdown delays were observed. The pressure was varied from 10^-6 Torr to 600 Torr to obtain breakdown delay characteristics according to pressure. The results of the fastest breakdown observed point toward a vacuum type discharge with field emitted electrons as the dominant breakdown mechanism, with a certain pressure of gas required to sustain the discharge across the test gap.Item Fast transient switching in bipolar junction transistors and metal-oxide-semiconductor field effect transistors(Texas Tech University, 1985-12) Menhart, SteveNot availableItem Impact of surface conditioning of large area electrodes on the dielectric strength of water(Texas Tech University, 2004-08) Wetz, David A.Due to water's high dielectric constant, 6r = 81, there is considerable interest in breakdown phenomena in water, particularly as an insulator and/or switching media in pulsed power systems. In numerous research efforts conducted over the last several decades, it has been documented that electrical breakdown in water is initiated from localized field enhancements on the electrode surface caused from asperities or microprotrusions on the electiode surface. The research conducted here attempts to determine the impact of electiode surface conditions on the holdoff voltage of a water gap. In this document, experimental results are presented on the impact electrode material and surface treatment has on the dielectric strength of water. A 4mm water gap was tested under pulsed conditions with pulse widths greater than 1 /is, peak electric fields over 1 MV/cm and peak currents over 20 kA. Stainless steel electrodes machined with a Bruce profile and an effective area of 5cm^ were tested with surface roughnesses ranging from .34 /.im to 1.41 /xm. Results comparing electiodes that have additionally been electropohshed are compared to those without an additional tieatinent. These various surface tieatments remove microprotrusions from the electiode surface and reduce localized field enhancements. It is believed that this technique will minimize the number of breakdown initiation points, thereby, increasing tiie dielectiic stiength. Results are given on the degree to which each finish improves the dielectiic stiength of water.Item Investigations of overvoltage breakdown(Texas Tech University, 1981-08) Levinson, Scott JosephAn experiment has been constructed to investigate the highly overvolted, electrical gas discharge for the following parameters: pressure (< 1 Torr - 1350 Torr), electrode spacing (1 and 2 cm), electric field (55-110 kV/cm) and electrode material (aluminum, brass, and graphite). In order to determine the effects of these parameters on the statistics associated with the observational time lag, an automated data acquisition system has been built to reduce large amounts of time lag data. An insulator has been placed over the anode in a number of experiments to examine the current waveforms resulting from electron space charge motion in the gap during the pre-breakdown stage. The results indicate that large^ fast rising (~ 1 ns) currents (~ 100 A) exist in the gap before a conducting plasma channel bridging the cathode and anode is formed. These initial currents appear to be the result of runaway electron space charge motion. The results of the statistical investigation indicate that: (1) the graphite electrode is a promising candidate in low jitter switching applications because of its large emissivity (~ le~/ns); (2) the statistics associated with the formative time lag are comparable to those of the statistical time lag (when graphite electrodes are used) at overvoltages as high as 400%. An apparent pressure dependency of the electron emission rate is a consequence of this result; (3) the formative time lag reaches an asymptotic value at the highest values of overvoltage investigated (- 2800%); and (4) the formative time lag is significantly larger than that predicted by the Streamer Theory (Raether's criteria), particularly at the highest values of overvoltage.Item Item Minimum supply voltage outlier analysis of large scale CMOS devices(Texas Tech University, 2004-05) McDonald, DavidThe theory and experiment of low voltage testing outlier screening methods will be proposed in this paper. Including an active study of maximum operating frequencies in comparison to their minimum voltage operating conditions. The objective of this paper is to discuss the possibility of using low voltage testing and outlier screening methods to reduce bum in time of large scale Integrated Circuits (IC's). In today's ever growing semiconductor market the need for test time reduction and test cost is ever present. By decreasing test overhead a company has the ability to lower product cost and manufacturing time and at the same time increasing potential profit and revenue.Item Multichannel surface discharge switch(Texas Tech University, 1983-08) Johnson, Donald EA system designed to investigate the performance of dielectrics in a multichannel surface discharge switch was built and tested. The apparatus consisted of a constant current charging supply that produced 10 mA at 50 kV, a storage capacitor, a 6-ohm stripline, the surface switch, a matched 5-ohra copper sulfate water load, and diagnostics. Diagnostics to evaluate the dielectric performance included capacitive voltage probes in the stripline, a video camera to record multichannel events on videocassettes, and an optically isolated counter to record the number of events in a test run. Typical operating parameters were: 180 joules per pulse, a peak voltage of 40-50 kV, and a peak current of 7 kA. Dielectric samples were tested by placing them in the switch for 19,000 shots at a repetition rate of 1-1.2 pulses per second. The dielectrics were then compared by observing their erosion, changes in breakdown voltage, and the number of channels that occur during discharges. Further analysis to study possible chemical change in the surfaces of three of the dielectrics was performed using Electron Spectroscopy for Chemical Analysis (ESCA).Item Pulsed power conditioning with strongly coupled transformers(Texas Tech University, 2004-05) Dixon, BrandonPower conditioning systems which transform high current, low voltage sources to high voltage, low current sources with minimal losses are useful in pulsed power applications. The use of strongly coupled transformers with a high step-up ratio can facilitate this transformation. This research explores the use of Current Transformers in power conditioning, the related theory, and the limitations due to core saturation. The experimental setup compares the saturation effects on one transformer with a large core to series connected transformers with smaller cores. Various simulation models are then designed to model the behavior of Current Transformers and the effects of leakage, saturation, and residual flux. A common application which needs power conditioning is a magnetic flux compression generator which typically outputs high amounts of current while the pulsed power load requires high voltages. A magnetic flux compression generator generates a fast-rising current. To capture the energy and generate high voltages, a tightly coupled transformer with a large step-up ratio can be used. The output current would be the primary current of the transformer. The experimental setup involves a primary capacitor discharged through a step-up transformer into a secondary capacitor. The secondary capacitor is used to capture and hold the energy. The simulation models are based on Ideal, Linear, Ben-Yaakov and Perertz, Empirical, and Linear Empirical models. The empirical data showed that the series connected transformers performed approximately the same as the equivalent single transformer and the empirical model correctly predicts the up to the peak voltage.Item Reverse bias second breakdown in power switching transistors(Texas Tech University, 1982-12) Skelton, Dale JamesNot availableItem The effect of space charge induced by an electon beam on spark gap operation(Texas Tech University, 1981-08) Tzeng, YonhuaAn investigation into the effect of electron beam induced space charge on the insulating property of a gas in a spark gap is presented. The characteristics of the gas transition from insulator to conductor show strong dependence on the amount and location of the space charge introduced. Investigations of the delay time and the characteristics of the conducting channel have been made. The delay time from the injection of the electron beam to the collapse of the gap voltage ranges from 10^-9 to 10^-3 second. From open shutter photography, we observe that the character of the conducting channel is quite varied. Dark, diffuse, filamentary, or diffuse followed by filamentary (single or multi) channels have been observed, depending on the space charge conditions. The fundamental processes leading to the collapse of insulating property of the gas for various experimental conditions are discussed.