Trident Scholar Abstracts 2008

This project seeks to develop new methodologies for improving the performance of a swarm of robotic vehicles in reconnaissance-based operations. The use of unmanned robotic platforms has mitigated some of the difficulties associated with reconnaissance, but robotic surveillance has its own difficulties in regards to overall effectiveness and efficiency. The unmanned robotic vehicle’s ability to carry out exploration missions is unparalleled by any human due to technological advances in electronic sensors. However, a single autonomous robot faces many limitations which potentially decrease its cost efficiency and hinder mission performance. A group of robots working together can remove many of the restrictions imposed on one single unit. However, controlling a group of robots is inherently more complex than controlling just one.

This project will use a novel coordination controller to direct the entire swarm and capability functions to direct individual unit movements. Each capability function will be determined based upon that unit’s specific payload and sensor configuration. The swarm will be able to autonomously explore an unknown area while maintaining a certain level of stealth and unit separation. This will allow the swarm to achieve its overall objective by providing more useful information on a target location. The first part of this project will focus on systems design and control. At the end of this phase, definition and design of the capability functions, primary and secondary objectives, a suitable test swarm and an appropriate test bed will be made and utilized in a simulation of the created controller. The Second part will migrate towards a focus on hardware implementation and will result in a real life demonstration of the designed control methodologies utilizing Khepera II Mobile Robots in a constructed environment. The robots will behave according to their individual capabilities and will work together in order to optimize the swarms overall performance.

 This research project involves an investigation of the interaction of carbon dioxide (CO₂) and selected room-temperature ionic liquids (RTILs). Raman spectroscopy and ab initio modeling will be performed on selected RTILs in contact with CO₂ in the effort to discover how the gas interacts with the solvent.

Currently on board U.S. submarines, monoethanolamine (MEA) is used as the CO₂ capture agent in scrubbing units. MEA is highly volatile, corrosive, physiologically toxic, foul-smelling, and requires replacement after approximately 1000 operational hours. A goal of the proposed project is to evaluate RTILs to replace MEA.

RTILs are salts (mixtures of cations and anions) that are liquid at room-temperature. Recent work has shown that gas solubilities in RTILs vary dramatically depending on the cation and anion that compose the RTIL. Tailoring the ion structures may therefore optimize the RTIL’s ability to dissolve CO₂. Further, the CO₂ solubility, negligible vapor pressure and high thermal stability of RTILs point to their potential application as CO₂ scrubbing chemicals.

A combined experimental and computational effort will investigate the factors which govern the CO₂ solubility mechanism. Initial studies will focus on six RTILs formed by the permutations of three anions: Hexafluorophosphate, tetrafluoroborate, bis(trifluoromethylsulfonyl)imide; and two cations: 1-ethyl-3-methylimidazolium, 1-butyl-3-methylimidazolium.

In-situ variable-temperature Raman spectroscopy will be performed on the selected RTILs in equilibrium with atmospheres of different CO₂ and N₂ partial pressures. Raman spectroscopy is an optical technique capable of resolving molecular vibrations characteristic to inter-molecular interactions. The vibrational frequencies attributed to the RTIL and CO₂ molecules are predicted to shift in response to the externally varied temperature and partial pressure of CO₂. The competing solvation mechanisms and application operating conditions will be explored by systematically varying the temperature and gas composition. Experimental considerations include enabling requisite convective mass transport of gas to establish equilibrium and limiting the sample water content.

    Ab initio computational modeling will be used to investigate the molecular pair interactions of the CO₂ with a select RTIL cations and anions. Gaussian03 and Spartan’02 will be used to compute optimized geometries and vibrational frequencies. The computed Raman vibrational modes will be attributed, correlated, and analyzed.

The combined experimental and computational treatment will expand the current molecular-level understanding of the physical interactions which facilitate selective thermodynamic solvation of CO₂ in various RTIL systems. The results will yield a quantitative rubric by which to choose an RTIL for use as a sorbant for submarine atmosphere purification.

This project is concerned with the gravitational lensing of light from the distant quasar QJ0158-4325 by a massive foreground galaxy. In such systems, the galaxy’s gravity causes multiple images of the quasar to appear to the observer. As the quasar undergoes brightness variations, gravitational slowing and differences in light travel path length cause time delays between the appearance of the intrinsic variability in each image.

These time delays depend on both the expansion rate of the universe and the distribution of matter in the lens galaxy. Time delay measurements are therefore useful for measuring the Hubble constant H₀, a number whose value parameterizes the expansion rate, as well as the distribution of so-called “dark matter” in the lens galaxy. This project’s primary goal is to determine the time delay of QJ0158-4325 and to make these measurements simultaneously.

The case of QJ0158-4325 is complicated by “microlensing” of the quasar light by stars in the lens galaxy.  Stars lack the gravitational potential to produce multiple observable images, but they do cause uncorrelated variability in the image fluxes as they pass in front of the quasar. Such variability must be eliminated in order to measure a time delay.  A series of physical models for the lens galaxy will be created to accurately model and remove the signal from microlensing.  This analysis will permit a time delay measurement and yield estimates of other physically interesting quantities, including the average stellar mass in the lens galaxy and the size of the quasar accretion disk.

This project will utilize over three years of flux monitoring data for QJ0158-4325.  The microlensing extraction will be performed using a Monte Carlo technique in which a series of microlensing simulations will be run using various combinations of physical parameters and testing a range of time delays. The goodness-of-fit of the simulated light curves to the data will then be used in a Bayesian analysis to determine a most likely value for the time delay.  The same analysis will be applied to estimate other physically interesting parameters, and the time delay will be compared to that generated by a series of mass models to determine the distribution of matter in the lens galaxy.

FACULTY ADVISOR
Lieutenant Commander Christopher W. Morgan, USNR
Physics Department

 
William H. Godiksen, III
Midshipman First Class
United States Navy

Computational Fluid Dynamics (CFD) Analysis of Store Separation from the
F/A-18C Configured with a Targeting Pod

This research project comprises an investigation into the effects of two different targeting pods on the store separation characteristics of munitions from the F/A-18C aircraft.  When these particular pods, the TFLIR and ATFLIR, were added to the underbody of an F/A18-C, they were not expected to have a significant effect on the trajectory of stores released from adjacent weapon carriage stations. At speeds approaching Mach 1, however, the addition of either targeting pod proved significant enough to cause the bomb to yaw into and to damage the side of the aircraft. As a result, a flight test study was conducted resulting in restrictions placed on the speeds at which pilots are permitted to release ordnance from this configuration.

The goal of this project is to investigate whether the influence of the targeting pods on the trajectories of released stores can be predicted using Computational Fluid Dynamics (CFD). The NASA-developed TetrUSS software suite will be used for geometry manipulation, grid generation, and flow solution. Comparisons will be made between existing wind tunnel data for an aircraft configuration that does not include a targeting pod, and CFD solutions generated for a similar configuration in order to establish model accuracy. Once established, flow solutions for configurations incorporating the ATFLIR and TFLIR targeting pods will be made and compared with pressure sensitive paint data available from recent wind tunnel tests, and CFD analysis using a different code conducted by the Canadian government for their CF-18 aircraft.

The final portion of this project will be predictions of the trajectories of munitions released adjacent to either the ATFLIR or TFLIR targeting pod from the F/A-18C aircraft. A quasi-steady approach will be taken using CFD to generate the aerodynamic data that captures the interference effects of the store in close proximity to the targeting pod. This data, in combination with existing wind tunnel data for the store alone, will serve as input to the Navy’s generalized store separation six-degree-of-freedom program, NAVSEP. The output from NAVSEP will be a prediction of the trajectory of the store when released. Comparisons to existing flight test telemetry for this store/aircraft configuration will serve to assess the validity of this method for store separation analysis.

The increased use of CFD for store separation analysis has the potential to dramatically reduce the overall costs of fielding both new combat aircraft and existing combat aircraft with new weapon systems through the reduction of hours required for wind tunnel and in-flight testing.

This research project involves an investigation of water injection into the compressor inlet of a Rolls-Royce Model 250 C20B gas turbine. Research has been conducted on steam and water injection into gas turbines; however, it has mainly focused on larger engines. The Model 250 C20B is a smaller engine with a lower pressure ratio. This project seeks to develop data on the effect of water ingestion into a small gas turbine, represented by the Rolls-Royce Model 250 C20B turbo shaft gas turbine.

Two Rolls-Royce Model 250 C20B gas turbines were recently acquired by the U. S. Naval Academy. The Model 250 C20B is comprised of a six stage axial compressor, a single stage centrifugal compressor, a single combustion chamber, a two stage gas generator turbine, and a two stage free power turbine. The 136 lb engine is rated at 500 shp (shaft horse power) and it has been fully instrumented.

The project will begin with thorough testing of the basic operation of the engine. This will provide baseline data to which the results of the water injection tests can be compared. After a spray mechanism is designed and fabricated, the engine will be run with various flow rates of water sprayed into the compressor inlet. The water flow rates will range from zero to ten percent of the mass flow rate of air of the basic cycle. Power and speed of the engine will also be varied. The effects of water injection on the performance of the engine, specifically the net power and the thermal efficiency, will be determined from the temperature and pressure data collected during the experimentation.

From previous research it is known that water injected as a fine spray or fog into the compressor inlet of larger gas turbines can yield favorable results. These include decreased compressor work, increased net work, increased thermal efficiency, and decreased nitrous oxide emissions. It is hoped that this project will yield similar results for the Model 250 C20B; however, it remains to be seen how significant the difference of pressure ratio in the Model 250 C20B will be. Whatever the outcome, this project will contribute to a better understanding of gas turbine operation and optimization.

A Coastal Ocean Circulation Model is a computer model of the movement of a fluid in a shallow water region: one where the horizontal dimensions of the fluid area are much larger than the vertical dimensions. The Chesapeake Bay is an excellent example of a fluid whose 30 mile width and 180 mile length are much more significant than its 150 foot depth at its deepest points.

The purpose of this project is to create a parallel implementation of a Coastal Ocean Circulation Model that is similar to the Princeton Ocean Model developed by Blumberg and Mellor in 1977. Since only hydrodynamics are considered, the mathematical model requires the conservation of mass equation and the three conservation of linear momentum equations. Temperature, density, and salinity are held constant for the purposes of simplicity in this work.

An algorithm, implemented in MATLAB^®, for depth averaged flow equations has already been developed by Dr. James Greenberg of Carnegie-Mellon Institute, an advisor on this project.  Dr. Greenberg’s equations are designed to be computed in parallel because the vertical layers do not interact during the first phase of calculations, allowing each layer to be analyzed by itself. This process is referred to as dimensional splitting and allows the problem to be divided into easier sub-problems. If this is successful, the result will be a wholly new model that is mathematically similar, but computationally different from the Princeton Ocean Model. The researcher's efforts in this project are concentrated in fully implementing the flow velocity algorithms, and creating a finished flow-solving program that is well documented and has a simple interface with a gentle learning curve.

This research project involves an investigation of parallel processing using reconfigurable logic devices.  The goal of this project is to support the Naval Research Laboratory’s recent acquisition of a Cray XD-1 supercomputer by automating the programming of its hardware. A feature of the Cray XD-1 is the utilization of reconfigurable logic devices in the form of Virtex-II Pro field programmable gate arrays (FPGA).  These devices can significantly improve the processing speed of computationally intensive operations. Recent technology has allowed FPGAs to process floating-point operations. Floating-point operations are more useful than integer operations for most scientific applications. Significant research is being done to explore how best to utilize FPGAs for parallel processing, but there is not yet one set standard.

A review of all available techniques will first be completed before development of a new technique is begun.  A new method will be based on the existing methods. The effectiveness of the designs created using the new method will be evaluated using a small portion of a problem deriving from the ray tracing of NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS). Previous research has used a single processor or multiple conventional processors in conjunction to address this problem. Work has also been done to manually customize a single FPGA to compute the MODIS computation.

This project seeks to evaluate automatic generation of FPGA designs. Automatically generated designs will be used in several instances and data will be taken in each case. The results from the previous research will be compared to results gathered from (1) running the MODIS simulation on a single FPGA, (2) running the simulation on the Cray XD-1’s 144 FPGAs, and (3) running the simulation simultaneously on a cooperating collection of the Cray XD-1’s FPGAs and conventional processors.

Proving that an automatic method for programming FPGAs can be as or more effective than previous techniques will justify continuing development in the field of parallel computing using FPGAs.  Such a method would also directly benefit researchers using the Cray XD-1 at the Naval Research Laboratory.

The goal of this research is to contribute to the development of a new, more effective antimalarial drug. Malaria is one of the few diseases which in modern times is killing an increasing number of people each year. This is due to the fact that malaria increasingly develops resistance to drugs used to combat its spread. Chalcones, the class of compound being used in this research is known to combat malaria by a different mechanism than other antimalarial drugs. This may prevent any of the plasmodium parasite, the parasite which causes malaria, from having an inherent resistance to any antimalarial drug created using them.

Via work done in the laboratory and beginning with commercially available compounds, the synthesis of a series of novel hybrid organic compounds possessing antimalarial properties will be undertaken. Each compound created will be synthesized through a four-step synthesis ending with a completely novel compound. Steps of the organic synthesis will include such techniques as vacuum filtration, acid hydrolysis, liquid-liquid extractions, column chromatography and thin-layer chromatography. Characterization and identification of compounds created will be accomplished through nuclear magnetic resonance and infrared spectroscopy. These compounds will then be tested in various assays, and should the results prove promising, the compounds would be further developed, in possibly collaboration with the US Army toward the ultimate goal of a novel antimalarial agents which treat the disease by a mechanism distinct from those used by preexisting treatments.

This research could eventually lead to more effective treatment of malaria and a reduction in the amount of deaths caused worldwide by the lethal disease.

The goal of this project is to predict soil vibration velocity profiles for the acoustic landmine problem by solving mathematical models analytically or numerically. Landmine detection and safe deactivation is a fundamental military and humanitarian mission. Experiments performed by Sabatier et al. indicate that plastic landmines, which are not detectable by radar, can potentially be detected using acoustic waves.

Currently, a theoretical prediction of acoustic landmine detection profiles has not been completed due to the complexity in the acoustic scattering of a compliant target that is located at an undetermined shallow burial depth. The modeling of the acoustic to seismic scattering results will employ coupled partial differential equations for the atmospheric sound, the soil medium, and the top plate surface of a cylindrically symmetric buried target. Solutions to these equations will be obtained using various analytical (when possible) and numerical methods such that one can determine the vibration velocity profile of the soil surface in the proximity of a buried landmine and compare it with off target results. These numerical methods include finite difference code in MATLAB^®, and may ultimately employ COMSOL’s partial differential equation solvers. The defining partial differential equations will include the mathematical impact from layered soil composition, soil depth, and propagation speed. The mathematical predictions will also be compared to the experimental results for both accuracy and precision. The model that will be developed in this project is a concrete step forward in landmine detection and eradication. Additionally, the results from this project are not strictly restricted to landmines, rather, the profiling technique could also be applied to buried or covered Improvised Explosive Devices (IEDs) and other enemy buried weaponry.

The goal of this research effort is to overcome one of the synthetic challenges posed by a class of organic compounds known as dolabellane diterpenes. These compounds are a class of molecules isolated mainly from marine organisms which possess a wide variety of biological activity, including potent anti-cancer activity. Due to the difficulty of isolating these compounds from their natural sources and their biological activity, interest in synthesizing the dolabellanes is high. Specifically, the synthetically difficult characteristics of dolabellanes are two-fold:  they contain a multi-functionalized eleven-membered ring which is fused to a cyclopentane ring bearing a quaternary stereocenter.  The aim of this project is to investigate a methodology for accomplishing the latter, with known stereochemistry.

To overcome the stereocontrol problems involved in reactions of conformationally labile cyclopentane rings, this project postulates that employing a fused bicyclopentane system will permit the creation of stereocenters with predictable chirality. This is made possible by the rigidity of the fused system, which will be energetically constricted to one conformation. Due to the sterics of the single conformation, the system will be biased towards substituent attack from only one direction. The bicyclic compound has been previously prepared and conformational studies, including X-ray crystallography, have verified its rigidity. The molecule has a cup-like shape, leading to the prediction that addition of new substituents will happen from the outer, convex, face of the molecule.

In this project, the ketone in the previously prepared bicyclic molecule will be converted to several different types of alkenes. Varying the type of alkene (α, β-unsaturated ketones to allylic systems) will allow for generation of the quaternary center using several different types of conjugate addition. The first conjugate addition that will be investigated is the 1,4-addition of organometallic reagents. By varying the identity of the metal, the parameters necessary to gain high regiocontrol and stereocontrol will be determined. Steric approach control of nucleophiles with different alkyl groups will be utilized to produce a quaternary center of varying identity. Types of nucleophiles will include different alkyl groups, such as butyl or tert-butyl. This will help in understanding the steric limits of the addition. Also, aryl and alkenyl nucleophiles can be used, allowing investigation of the electronic factors. After investigation of the 1,4-addition is complete, another means of producing the quaternary center, the S_n2′ reaction, will be investigated. This complementary method will allow for varying the functional group remaining after the introduction of the quaternary center.

This research project involves an investigation of seafloor embedment depth of objects larger than three inches in diameter. The goals of this project are (1) to better understand the soil dynamics involved in seafloor penetration; and (2) to improve upon the existing algorithms for prediction of penetration depth. Improvements of the existing algorithms will be made for the purpose of better predicting the depth of penetration into the seafloor of objects larger than three inches in diameter. The new algorithms may be used to predict the depth to which an object will penetrate or the force required for a specified depth penetration. These algorithms could apply to objects such as gravity anchors, gravity corers and penetrometers, and propellant-embedded anchor plates. Application of this research also applies not only to the Navy, but to oil extraction, pile driving, and underwater mines.

Using the Naval Academy's Oceanography Department Yard Patrol (YP) craft, penetrometers of varying diameters will be repeatedly dropped off the stern of the YP and allowed to free fall to the seabed. Several sites with differing soil parameters will be used. The data acquisition system on-board the YP will start recording accelerometer output before release and continually throughout the drop. By integrating the acceleration data, the velocity of the penetrometer can be obtained, and a second integration will yield the distance traveled. Using this experimental data and equations available in the Handbook for Marine Geotechnical Engineering, new values will be calculated for the strain rate factors of objects larger than three inches in diameter.

A computational analysis of the seabed penetration problem will also be conducted using the LS-DYNA finite element analysis (FEA) code. LS DYNA^® will be used to model the experiments, and then the model predictions will be compared to experimental results. If the model shows reasonable agreement, then a parametric study will be conducted to further develop the empirical strain rate constants.

This research into sediment strain-rate dependence on penetrator diameter has the potential to significantly improve the Navy’s ability to predict embedment depth of objects placed-on or impacting the seabed. The experimental portion of the study will extend past published work by increasing object diameter, and the large-deformation finite element analysis will provide more understanding of the dynamic soil-structure interaction problem.

The goal of this project is to improve the efficiency of the Magnesium - Hydrogen Peroxide (Mg-H₂O₂) semi-fuel cell by altering the carbon-based cathode. The project will demonstrate the viability of carbon aerogels in semi-fuel cell systems, adding to the body of knowledge concerning electrochemical applications for nanoarchitectures.  Magnesium-hydrogen peroxide semi-fuel cells have been studied extensively as the primary power source for unmanned underwater (UUV) vehicles in the U.S. Navy. Semi-fuel technology combines characteristics of classical batteries and fuel cells, using a consumed anode (like a battery) and purely catalytic cathode (like a fuel cell).

This project will be the first investigation into incorporating novel carbon aerogels as cathodes in semi-fuel cell systems. The carbon aerogels incredible potential for increasing the efficiency of semi-fuel cells is due to the aerogels tunable pore size and incredible surface area, on the scale of 10⁶ ratio of surface area to volume. The carbon aerogels can be created to have a pore size that allows for high analyte movement through the structure and the huge surface area creates more sites for the reduction reactions to occur. Initially, the basic carbon aerogels nanostructures will be synthesized and characterized, then tested in an aqueous environment for structural stability. Catalytic metal nanoparticles (primarily palladium and palladium-iridium alloys) will be chemically anchored to the carbon network of the aerogel nanostructure to facilitate the cathodic chemical reaction. A simple semi-fuel cell will be fabricated using the carbon aerogel cathode and tested to determine how the aerogel cathode increases the performance of the semi-fuel cell in terms of power output and peroxide utilization.

Life on earth became possible as oxygen accumulated in the atmosphere, but as humans age, oxygen accumulates in our bodies often causing irreversible damage to cells and body proteins. Many studies have shown pathophysiological evidence strongly linking oxidative cell damage to neurodegenerative and age-related diseases such as Alzheimer’s disease, Parkinson’s disease, Lou Gehrig’s, emphysema, and arthritis. The amino acid methionine is particularly sensitive to damage by reactive oxygen species. While most oxygen damage is irreversible, the enzyme Methionine sulfoxide reductase A (MsrA) has been found to be capable of scavenging and repairing methionines of damaged proteins to allow a protein to function normally again.

This study focuses on understanding how MsrA is able to recognize then repair such a range of damaged proteins. This research project will investigate whether MsrA acts as a molecular chaperone, recognizing overall characteristics of a damaged and unfolded target molecule. The kinetics of association of MsrA with oxidized and reduced forms of Staphylococcus nuclease protein and peptide substrates (target molecules) will be investigated. By observing how quickly MsrA recognizes these target molecules that have been modified in different ways, the features of proteins MsrA really recognizes - whether it is specifically the oxygen modification on methionine or secondary features of damaged proteins that result from the oxygen modification will be determined. Using stopped-flow fluorescence spectroscopy, the rate of recognition of MsrA for the various target molecules will be compared. The extent of substrate repair will be determined by using MALDI-TOF mass spectroscopy to compare the relative mass of substrates before and after repair. Circular dichroism spectroscopy will give insight on to the secondary structure of the MsrA-substrate complex during and after repair.

Understanding this recognition mechanism may give significant insight into the development of novel drugs and treatments that could serve as catalytic antioxidants in the fight against neurodegenerative disease.

In this research project, work will be undertaken to improve the method for in vitro selection of beacon aptamers.  An aptamer is any molecule that binds to and aids in the quantification of any specific target molecule. They are used in countless areas of chemistry, and more and more uses are being found for them. One specific type is the beacon aptamer, which is an RNA sequence that undergoes a conformational change when it binds to a specific molecule. Attached to the molecule is a fluorophore and a quencher, which are molecules that release and absorb light, respectively. When the ligand, or target molecule, is not bound then the fluorophore and quencher are close to each other, allowing theoretically little to no light to escape. When the ligand binds it forces the beacon aptamer to change shape, causing the quencher to move away from the fluorophore, allowing the amount of fluorescence and thus amount of ligand present to be measured.

The primary focus of this research will be to find an RNA sequence that can be converted into a functional tobramycin beacon aptamer. Rather than starting with a totally random collection of RNAs, a new selection will be performed starting with a pool of RNAs that are all closely related to one of the previously selected marginally functioning tobramycin beacon aptamers. Additional sequence variants will be produced during the selection by performing the amplification step under conditions that reduce the fidelity of replication. Improved variants will be selected by increasing the "selection pressure" in various ways, including reducing the tobramycin concentration and the elution time.

Beacon aptamers can be used for a wide array of applications. They could be used by the military to detect chemical or biological warfare agents. They could also be used in medicine for diagnostic purposes or by environmental scientists to study the amount of pollutants or toxins in a certain region. Of particular interest are their potential ability to quantify specific molecules in cells and within the body. There is great interest in developing methods for the efficient production of functional beacon aptamers, something that has proven difficult to date with the currently employed techniques.

This research project involves an investigation of the current interruption capacity of Gate Turn Off Thyristors (GTOs). A series of GTO devices will be used with different gate drivers and protection circuits to interrupt different levels of current. The objective of this project is to determine if the gate driving circuitry of a GTO can be modified to optimize its current interruption capacity for use as an opening switch in an inductive pulse forming network.

This project will benefit the current research work that is being performed for the Navy railgun weapon systems. Significant research is being done to develop a pulse power system that can meet the energy requirements of the railgun weapon while being small enough to fit into the ship. Current research indicates that inductive pulse forming network could satisfy the “energy-density” requirements of a naval railgun system.

Unfortunately, inductive pulse forming networks require high-current opening switches to initiate the output current pulse. The opening switch interrupts the current that supplies energy to the inductor and causes the inductor to output that energy as a pulse of high current. It is important for the switch to rapidly interrupt the charging current in order to maximize the efficiency of the resulting current pulse. The challenge is to find a switching device that can achieve a fast turn-off time and tolerate the large charging current.

One promising type of switching device is known as a Gate Turn Off Thyristor (GTO); a GTO is a solid-state electronic switches that can be turned on and off with control current pulses. Several research projects have shown that some GTOs can be used in a pulse power system to interrupt currents that are significantly higher than their specified "maximum interruptible current." The research projects did not determine why the GTO’s could interrupt higher than rated currents.

This project will test a series of GTO’s to determine their ability to interrupt current in a pulse power system. The tests will determine if the different gate current pulses affect the maximum current that the switches can interrupt. Additionally, the project will characterize the voltage-current characteristics of the GTO’s to determine how the switches behave when used to interrupt higher than rated currents. Ultimately, this project will determine if the gate control circuitry can be modified to maximize the current interruption capacity of a gate turn off thyristor.