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The Use of Thyristors for Repetitive Narrow Pulse, High Power Switching

Description: Inverter type thyristors were switched repetitively to failure with 1 {micro}s pulses at repetition rates of 10, 50 and 100 pps and at peak currents up to 12 kA. Millions of pulses could be obtained before failure if the peak current were held at around 6 kA.
Date: January 13, 2000
Partner: UNT Libraries Government Documents Department

Design and testing of high power, repetitively pulsed solid-state closing switches

Description: Repetitively pulsed closing switches are often required in high-power physics experiments. Traditionally, ignitrons have been used for these applications. There are reasons why ignitrons have undesirable features, such as the high trigger current which causes electromagnetic interference, the arc instability and environmental concern with the mercury used in the switches. With the development of ever increasing power rating of solid-state switches, in particular thyristors, the designer has the tools to replace ignitrons with solid-state devices. Using as an example a recently designed and tested 10 kV, 80 kA high-power switch, the design philosophy for repetitively pulsed switches is developed. The parameters which impose the greatest challenge on the device, such as di/dt, temperature rise and reverse blocking voltage are investigated with respect to their capability when operating in the pulsed mode. Starting with the available device data sheet information and published results of the dependency of the number of life cycles as a function of the device temperature, it is shown how the overload capability of a device for short term pulsed applications can be exploited. The detailed design of a 2 Hz, 10{sup 8} cycle, 12.5 kV, 80 kA, 3 ms switch, with a short circuit capability of 250 kA, is presented. The paper concludes with a short summary about device limits in voltage, current amplitude and pulse length ratings for repetitively pulsed switches using available thyristors.
Date: April 1, 1997
Creator: Boenig, H.J.; Schwartzenberg, J.W.; Willinger, L.J.; Piccone, D.E.; Lopez, D.A. & Smolleck, H.A.
Partner: UNT Libraries Government Documents Department

MOS-Gated Thyristors (MCTs) for Repetitive High Power Switching

Description: Certain applications for pulse power require narrow, high current pulses for their implementation. This work was performed to determine if MCTS (MOS Controlled Thyristors) could be used for these applications. The MCTS were tested as discharge switches in a low inductance circuit delivering 1 {micro}s pulses at currents between roughly 3 kA and 11 kA, single shot and repetitively at 1, 10 and 50 Hz. Although up to 9000 switching events could be obtained, all the devices failed at some combination of current and repetition rate. Failure was attributed to temperature increases caused by average power dissipated in the thyristor during the switching sequence. A simulation was performed to confirm that the temperature rise was sufficient to account for failure. Considerable heat sinking, and perhaps a better thermal package, would be required before the MCT could be considered for pulse power applications.
Date: January 13, 2000
Partner: UNT Libraries Government Documents Department

Early-time turn-on characteristics of a high current thyristor

Description: Studies and experiments aimed at increasing the turn-on speed of high current thyristors have been carried out in recent years to meet an expanding need in the pulsed power handling capacity and high pulse repetition rate capability. The present tests were conducted to measure the early-time turn-on characteristics of ABB 2003-45A02 thyristors and to determine whether special triggering techniques could raise the safe turn-on rate to the 100,000 A/{micro}s range which would qualify it for applications such as direct drive accelerator circuits. Results were encouraging. With these devices and special triggering techniques a maximum turn-on rate of 65,373 A/{micro}s and a peak current of 19,040 A were recorded at a pulse repetition rate of 5 Hz.
Date: July 1, 1996
Creator: Roose, L.D. & Rohwein, G.J.
Partner: UNT Libraries Government Documents Department

Design of a gate-turn-off (GTO) switch for pulsed power application.

Description: A Gate-Turn-Off (GTO) thyristor switch and its gate drive circuit have been developed as a replacement for the thyratron switch used in the positron converter solenoid lens power supply at the Advanced Photon Source (APS) to deliver a current pulse of 6000 A at 60-Hz repetition rate. This paper discusses the characteristics of the GTOs under consideration, the gate drive circuit, and some test results.
Date: July 10, 1998
Creator: Despe, O.
Partner: UNT Libraries Government Documents Department

Estimating damping effectiveness of BPA`s thyristor controlled series capacitor by applying time and frequency domain methods to measured response

Description: Recently, a 500-kV thyristor controlled series capacitor (TCSC) was installed in the Bonneville Power Administration system in the northwestern United States. Extensive field testing has included modulation experiments to determine the effect of the TCSC on low- frequency procedures, analysis methods, and results for estimating the damping effectiveness of the TCSC. Modulation methods include driving the TCSC with step and random noise, and analysis techniques include time (Prony analysis) and frequency-domain identification. Results indicate that: (1) the TCSC can have significant impact on system dynamics; and (2) under a very small feedback gain, the TCSC provides measurable added damping.
Date: July 1995
Creator: Trudnowski, D. J.; Donnelly, M. K. & Hauer, J. F.
Partner: UNT Libraries Government Documents Department


Description: A new 5kV, 1.5MJ modular capacitor bank has been designed for the Sustained Spheromak Physics Experiment (SSPX) at LLNL. The new bank consists of thirty 4mF capacitors that are independently controlled by light-triggered thyristors. By closing all switches simultaneously, the bank will provide a mega-ampere discharge. The new bank will also allow additional capabilities to SSPX, including higher peak gun current, longer current pulses, and multi-pulse plasma buildup. Experiment results for a single stage prototype will be presented, deliver a single large current spike, or, switches can be triggered in sequence to deliver a longer lower current pulse. Multiple pulses can be created by triggering sections of the modular bank in intervals.
Date: May 31, 2005
Creator: Marchiano, M M; Cook, E G; Geer, R W; Kemptner, R O; McLean, H S; Martovetsky, N N et al.
Partner: UNT Libraries Government Documents Department

Commissioning of the new AGS MMPS transformers

Description: The Brookhaven AGS Main Magnet Power Supply (MMPS) is a thyristor control supply rated at 5500 Amps. +/-9000 Volts. The peak magnet power is 50 MWatts. The power supply is fed from a motor/generator manufactured by Siemens. During rectify and invert operation the P Bank power supplies are used. During the flattops the F Bank power supplies are used. The P Bank power supplies are fed from two 23 MVA transformers and the F Bank power supplies are fed from two 5.3 MYA transformers. The fundamental frequency of the F Bank power supplies is 1440 Hz, however the fundamental frequency of the P banks was 720 Hz. It was very important to reduce the ripple during rectify to improve polarized proton operations. For this reason and also because the original transformers were 45 years old we replaced these transformers with new ones and we made the fundamental frequency of both P and F banks 1440 Hz. This paper will highlight the major hurdles that were involved during the installation of the new transformers. It will present waveforms while running at different power levels up to 6MW full load. It will show the transition from the F-Bank power supplies to the P-Banks and also show the improvements in ripple made on the P-Bank power supplies.
Date: May 4, 2009
Creator: Bajon,E.; Badea, V. S.; Bannon, M.; Bonati, R.; Marneris, I. M.; Porqueddu, r. et al.
Partner: UNT Libraries Government Documents Department

Ultrafast gas switching experiments

Description: We describe recent experiments which studied the physics of ultrafast gas breakdown under the extreme overvoltages which occur when a high pressure gas switch is pulse charged to hundreds of kV in 1 ns or less. The highly overvolted peaking gaps produce powerful electromagnetic pulses with risetimes < 100 ps which can be used for ultrawideband radar systems, particle accelerators, laser drivers, bioelectromagnetic studies, electromagnetic effects testing, and for basic studies of gas breakdown physics. We have produced and accurately measured pulses with 50 to 100 ps risetimes to peak levels of 75 to 160 kV at pulse repetition frequencies (PRF) to I kHz. A unique gas switch was developed to hold off hundreds of kV with parasitic inductance less than I nH. An advanced diagnostic system using Fourier compensation was developed to measure single-shot risetimes below 35 ps. The complete apparatus is described and wave forms are presented. The measured data are compared with a theoretical model which predicts key features including dependence on gas species and pressure. We have applied this technology to practical systems driving ultrawideband radiating antennas and bounded wave simulators. For example, we have developed a thyristor/pulse transformer based system using a highly overvolted cable switch. This pulser driving a Sandia- designed TEM cell, provides an ultra wideband impulse with < 200 ps risetime to the test object at a PRF > 1 kHz at > 100 kV/m E field.
Date: November 1, 1996
Creator: Frost, C.A.; Martin, T.H.; Patterson, P.E.; Rinehart, L.F.; Rohwein, G.J.; Roose, L.D. et al.
Partner: UNT Libraries Government Documents Department

Testing results for the HCT-1400 switch

Description: The High Current Thyristor (HCT)-1400 was characterized for switching performance. This is a Soviet switching device that has recently become available to the U.S. community. Substantial claims have been made regarding the performance of this switch. In particular, the switch was claimed to be able to switch high currents, with very short risetime without any significant jitter. This is an independent evaluation of the high current thyristor.
Date: July 1, 1996
Creator: Hoeberling, R.F. & Wheeler, R.B.
Partner: UNT Libraries Government Documents Department

Control of Surface Mounted Permanent Magnet Motors with Special Application to Fractional-Slot Concentrated Windings

Description: It is well known that the ability of the permanent magnet synchronous machine (PMSM) to operate over a wide constant power speed range (CPSR) is dependent upon the machine inductance [1,2,3,4,5]. Early approaches for extending CPSR operation included adding supplementary inductance in series with the motor [1] and the use of anti-parallel thyristor pairs in series with the motor-phase windings [5]. The increased inductance method is compatible with a voltage-source inverter (VSI) controlled by pulse-width modulation (PWM) which is called the conventional phase advance (CPA) method. The thyristor method has been called the dual mode inverter control (DMIC). Neither of these techniques has met with wide acceptance since they both add cost to the drive system and have not been shown to have an attractive cost/benefit ratio. Recently a method has been developed to use fractional-slot concentrated windings to significantly increase the machine inductance [6]. This latest approach has the potential to make the PMSM compatible with CPA without supplemental external inductance. If the performance of such drive is acceptable, then the method may make the PMSM an attractive option for traction applications requiring a wide CPSR. A 30 pole, 6 kW, 6000 maximum revolutions per minute (rpm) prototype of the fractional-slot PMSM design has been developed [7]. This machine has significantly more inductance than is typical of regular PMSMs. The prototype is to be delivered in late 2005 to the Oak Ridge National Laboratory (ORNL) for testing and development of a suitable controller. In advance of the test/control development effort, ORNL has used the PMSM models developed over a number of previous studies to study the steady-state performance of high-inductance PMSM machines with a view towards control issues. The detailed steady-state model developed includes all motor and inverter-loss mechanisms and will be useful in assessing the performance of the ...
Date: December 21, 2005
Creator: Lawler, J.S.
Partner: UNT Libraries Government Documents Department

Ultra-high implant activation efficiency in GaN using novel high temperature RTP system

Description: Si{sup +} implant activation efficiencies above 90%, even at doses of 5 {times} 10{sup 15} cm{sup {minus}2}, have been achieved in GaN by RTP at 1,400--1,500 C for 10 secs. The annealing system utilizes with MoSi{sub 2} heating elements capable of operation up to 1,900 C, producing high heating and cooling rates (up to 100 C{center_dot}s{sup {minus}1}). Unencapsulated GaN show severe surface pitting at 1,300 C, and complete loss of the film by evaporation at 1,400 C. Dissociation of nitrogen from the surface is found to occur with an approximate activation energy of 3.8 eV for GaN (compared to 4.4 eV for AlN and 3.4 eV for InN). Encapsulation with either rf-magnetron reactively sputtered or MOMBE-grown AlN thin films provide protection against GaN surface degradation up to 1,400 C, where peak electron concentrations of {approximately} 5 {times} 10{sup 20} cm{sup {minus}3} can be achieved in Si-implanted GaN. SIMS profiling showed little measurable redistribution of Si, suggesting D{sub Si} {le} 10{sup {minus}13} cm{sup 2}{center_dot}s{sup {minus}1} at 1,400 C . The implant activation efficiency decreases at higher temperatures, which may result from Si{sub Ga} to Si{sub N} site switching and resultant self-compensation.
Date: April 1, 1998
Creator: Cao, X.A.; Abernathy, C.R. & Singh, R.K.
Partner: UNT Libraries Government Documents Department

National Spherical Torus Experiment Real Time Plasma Control Data Acquisition Hardware

Description: The National Spherical Torus Experiment (NSTX) is currently providing researchers data on low aspect-ratio toroidal plasmas. NSTX's Plasma Control System adjusts the firing angles of thyristor rectifier power supplies, in real time, to control plasma position, shape and density. A Data Acquisition system comprised of off-the-shelf and custom hardware provides the magnetic diagnostics data required in calculating firing angles. This VERSAmodule Eurocard (VME) bus-based system utilizes Front Panel Data Port (FPDP) for high-speed data transfer. Data coming from physically different locations is referenced to several different ground potentials necessitating the need for a custom FPDP multiplexer. This paper discusses the data acquisition system configuration, the in-house designed 4-to-1 FPDP Input Multiplexing Module (FIMM), and future expansion plans.
Date: August 5, 2002
Creator: Marsala, R. J. & Schneider, J.
Partner: UNT Libraries Government Documents Department

Thyristor converter simulation and analysis

Description: In this paper we present a simulation on thyristor converters. The simulation features nonlinearity, non-uniform firing, and the commutations. Several applications such as a current regulation, a converter frequency characteristics analysis, and a power line disturbance analysis will be presented. 4 refs., 4 figs.
Date: January 1, 1991
Creator: Zhang, S.Y.
Partner: UNT Libraries Government Documents Department

A SPICE Model and Electrostatic Field Analysis of the MOS Turn-Off Thyristor

Description: This paper presents a circuit model and an electrostatic field analysis with an approximate model of the SDM170HK MOS turn-off thyristor (MTO) fabricated by Silicon Power Corporation. The circuit model consists of five cells, each containing two bipolar junction transistors and three resistors. The turn-off feature of the MTO was simulated by inserting an array of 21 Fairchild FDS6670A MOSFET importable sub-circuit components between the cathode and the turn-on gate. The model was then used to create a four-terminal sub-circuit component representing the MTO that can be readily imported into computer-aided circuit design programs such as PSPICE and Micro-Cap. The generated static I-V characteristics and simulated switching waveforms are shown. The electrostatic field analysis was done for the maximum operating voltage of 4.5 kV using the Ansoft Maxwell 3D field simulator. Electrostatic field magnitudes that exceed the nominal air breakdown threshold of 30 kV/cm were observed surrounding the simulated turn-off gate wire, the turn-off gate ring contact, and the cathode ring contact. The resulting areas of high fields are a concern, as arc track marks have been found on the inner surface of the ceramic insulator near the internal gate connections of a failed device.
Date: August 5, 2002
Creator: Kelly, D Q; Mayhall, D J; Wilson, M J & Lahowe, D A
Partner: UNT Libraries Government Documents Department

Superconducting fault-current limiter and inductor design

Description: A superconducting fault current limiter (SFCL) that uses a biased superconducting inductor in a diode or thyristor bridge circuit was analyzed for transmission systems in 69, 138, and 230 rms kV utility transmission systems. The limiter was evaluated for costs with all components - superconducting coil, diode and/or SCR power electronics, high voltage insulation, high voltage bushings and vapor cooled leads, dewar, and refrigerator - included. A design was undertaken for the superconducting cable and coils for both diode and SCR 69 kV limiter circuits.
Date: January 1, 1982
Creator: Rogers, J.D.; Boenig, H.J.; Chowdhuri, P.; Schermer, R.I.; Wollan, J.J. & Weldon, D.M.
Partner: UNT Libraries Government Documents Department

Booster main magnet power supply, present operation and potential future upgrades

Description: The Brookhaven Booster Main Magnet Power Supply (MMPS) is a 24 pulse thyristor control supply, rated at 5500 Amps, +/-2000 Volts, or 3000 Amps, +/-6000 Volts. The power supply is fed directly from the power utility and the peak magnet power is 18 MWatts. This peak power is seen directly at the incoming ac line. This power supply has been in operation for the last 18 years. This paper will describe the present topology and operation of the power supply, the feedback control system and the different modes of operation of the power supply. Since the power supply has been in operation for the last 18 years, upgrading this power supply is essential. A new power supply topology has been studied where energy is stored in capacitor banks. DC to DC converters are used to convert the dc voltage stored in the capacitor banks to pulsed DC voltage into the magnet load. This enables the average incoming power from the ac line to be constant while the peak magnet power is pulsed to +/- 18 MWatts. Simulations and waveforms of this power supply will be presented.
Date: March 28, 2011
Creator: Bajon, E.; Bannon, M.; Marneris, I.; Danowski, G.; Sandberg, J. & Savatteri, S.
Partner: UNT Libraries Government Documents Department


Description: The Brookhaven AGS Main Magnet Power Supply (MMPS) is a thyristor control supply rated at 5500 Amps, +/-9000 Volts. The peak magnet power is 50 MWatts. The power supply is fed from a motor/generator manufactured by Siemens. The generator is 3 phase 7500 Volts rated at 50 MVA. The peak power requirements come from the stored energy in the rotor of the motor/generator. The motor generator is about 45 years old, made by Siemens and it is not clear if companies will be manufacturing similar machines in the future. We are therefore investigating different ways of storing energy for future AGS MMPS operations. This paper will present simulations of a power supply where energy is stored in capacitor banks. Two dc to dc converters will be presented along with the control system of the power section. The switching elements will be IGCT's made by ABB. The simulation program used is called PSIM version 6.1. The average power from the local power authority into the power supply will be kept constant during the pulsing of the magnets at +/-50 MW. The reactive power will also be kept constant below 1.5 MVAR. Waveforms will be presented.
Date: June 25, 2007
Partner: UNT Libraries Government Documents Department

A Preliminary Cost Study of the Dual Mode Inverter Controller

Description: In 1998, the Power Electronics and Electric Machinery Research Center (PEEMRC) at the Oak Ridge National Laboratory (ORNL) started a program to investigate alternate field weakening schemes for permanent magnet (PM) motors. The adjective ''alternate'' was used because at that time, outside research emphasis was on motors with interior-mounted PMs (IPMs). The PEEMRC emphasis was placed on motors with surface-mounted PMs (SPMs) because of the relative ease of manufacturing SPM motors compared with the IPM motors. Today the PEEMRC is continuing research on SPMs while examining the IPMs that have been developed by industry. Out of this task--the goal of which was to find ways to drive PM motors that inherently have low inductance at high speeds where their back-emf exceeds the supply voltage--ORNL developed and demonstrated the dual mode inverter control (DMIC) [1,2] method of field weakening for SPM motors. The predecessor of DMIC is conventional phase advance (CPA), which was developed by UQM Technologies, Inc. [3]. Fig. 1 shows the three sets of anti-parallel thyristors in the dashed box that comprise the DMIC. If one removes the dashed box by shorting each set of anti-parallel thyristors, the configuration becomes a conventional full bridge inverter on the left driving a three phase motor on the right. CPA may be used to drive this configuration ORNL's initial analyses of CPA and DMIC were based on driving motors with trapezoidal back-emfs [4-6], obtained using double layer lapped stator windings with one slot per pole per phase. A PM motor with a sinusoidal back-emf obtained with two poles per slot per phase has been analyzed under DMIC operation as a University of Tennessee-Knoxville (UTK) doctoral dissertation [7]. In the process of this research, ORNL has completed an analysis that explains and quantifies the role of inductance in these methods of control. The ...
Date: January 28, 2005
Creator: McKeever, J.W.
Partner: UNT Libraries Government Documents Department

CRADA Final Report: Application of Dual-Mode Inverter Control to Commercially Available Radial-Gap Mermanent Magnet Motors - Vol. I

Description: John Deere and Company (Deere), their partner, UQM Technologies, Inc. (UQM), and the Oak Ridge National Laboratory's (ORNL's) Power Electronics and Electric Machinery Research Center (PEEMRC) recently completed work on the cooperative research and development agreement (CRADA) Number ORNL 04-0691 outlined in this report. CRADA 04-0691 addresses two topical issues of interest to Deere: (1) Improved characterization of hydrogen storage and heat-transfer management; and (2) Potential benefits from advanced electric motor traction-drive technologies. This report presents the findings of the collaborative examination of potential operational and cost benefits from using ORNL/PEEMRC dual-mode inverter control (DMIC) to drive permanent magnet (PM) motors in applications of interest to Deere. DMIC was initially developed and patented by ORNL to enable PM motors to be driven to speeds far above base speed where the back-electromotive force (emf) equals the source voltage where it is increasingly difficult to inject current into the motor. DMIC is a modification of conventional phase advance (CPA). DMIC's dual-speed modes are below base speed, where traditional pulse-width modulation (PWM) achieves maximum torque per ampere (amp), and above base speed, where six-step operation achieves maximum power per amp. The modification that enables DMIC adds two anti-parallel thyristors in each of the three motor phases, which consequently adds the cost of six thyristors. Two features evaluated in this collaboration with potential to justify the additional thyristor cost were a possible reduction in motor cost and savings during operation because of higher efficiency, both permitted because of lower current. The collaborative analysis showed that the reduction of motor cost and base cost of the inverter was small, while the cost of adding six thyristors was greater than anticipated. Modeling the DMIC control displayed inverter efficiency gains due to reduced current, especially under light load and higher speed. This current reduction, which is the ...
Date: May 1, 2006
Creator: McKeever, John W; Lawler, Jack; Downing, Mark; Stahlhut, Ronnie D; Bremmer, R.; Shoemaker, J. M. et al.
Partner: UNT Libraries Government Documents Department


Description: The Brookhaven AGS is a strong focusing accelerator which is used to accelerate protons and various heavy ion species to equivalent maximum proton energy of 29 GeV. The AGS Main Magnet Power Supply (MMPS) is a thyristor control supply rated at 5500 Amps, +/-go00 Volts. The peak magnet power is 49.5 Mwatts. The power supply is fed from a motor/generator manufactured by Siemens. The motor is rated at 9 MW, input voltage 3 phase 13.8 KV 60 Hz. The generator is rated at 50 MVA its output voltage is 3 phase 7500 Volts. Thus the peak power requirements come from the stored energy in the rotor of the motor/generator. The rotor changes speed by about +/-2.5% of its nominal speed of 1200 Revolutions per Minute. The reason the power supply is powered by the Generator is that the local power company (LIPA) can not sustain power swings of +/- 50 MW in 0.5 sec if the power supply were to be interfaced directly with the AC lines. The Motor Generator is about 45 years old and Siemens is not manufacturing similar machines in the future. As a result we are looking at different ways of storing energy and being able to utilize it for our application. This paper will present simulations of a power supply where energy is stored in capacitor banks. The simulation program used is called PSIM Version 6.1. The control system of the power supply will also be presented. The average power from LIPA into the power supply will be kept constant during the pulsing of the magnets at +/-50 MW. The reactive power will also be kept constant below 1.5 MVAR. Waveforms will be presented.
Date: September 1, 2006
Creator: MARNERIS, I.
Partner: UNT Libraries Government Documents Department

Critical pulse power components

Description: Critical components for pulsed power conditioning systems will be reviewed. Particular emphasis will be placed on those components requiring significant development efforts. Capacitors, for example, are one of the weakest elements in high-power pulsed systems, especially when operation at high-repetition frequencies for extended periods of time are necessary. Switches are by far the weakest active components of pulse power systems. In particular, opening switches are essentially nonexistent for most applications. Insulaton in all systems and components requires development and improvement. Efforts under way in technology base development of pulse power components will be discussed.
Date: January 1, 1981
Creator: Sarjeant, W.J. & Rohwein, G.J.
Partner: UNT Libraries Government Documents Department

Static reactive power compensators for high-voltage power systems. Final report

Description: A study conducted to summarize the role of static reactive power compensators for high voltage power system applications is described. This information should be useful to the utility system planning engineer in applying static var systems (SVS) to high voltage as (HVAC) systems. The static var system is defined as a form of reactive power compensator. The general need for reactive power compensation in HVAC systems is discussed, and the static var system is compared to other devices utilized to provide reactive power compensation. Examples are presented of applying SVS for specific functions, such as the prevention of voltage collapse. The operating principles of commercially available SVS's are discussed in detail. The perormance and active power loss characteristics of SVS types are compared.
Date: April 1, 1981
Partner: UNT Libraries Government Documents Department

Application of power-factor correction in the Tandem Mirror Experiment Upgrade magnet power supply

Description: The magnet power supply for the Tandem Mirror Experiment Upgrade (TMX Upgrade) contains 24 groups of dc rectifiers that feed the water-cooled magnets. Each group consists of five or less rectifiers, connected in series. All 24 are current-regulating, using phase-controlled bilateral thyristors in the rectifier transformer primaries. The electric utility system must furnish reactive power to these phase-controlled thyristors as well as to the cmmutating diodes in the rectifier bridges.
Date: August 14, 1981
Creator: Corvin, W.C.
Partner: UNT Libraries Government Documents Department