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The research for the development of new types of detectors for analysis of planetary atmospheres is summarized. Topics discussed include: corona discharge humidity detector, surface catalysis and exo-electron emission, and analysis of soil samples by means of exo-electron emission. A report on the exo-electron emission during heterogeneous catalysis is included.
Ion bundles produced in a pulse-excited corona discharge are used as tracers with a radar-like pulse transit-time measuring instrument in order to provide a measurement of airspeed that is independent of all variables except time and distance. The resulting instrumentation need not project into the air stream and, therefore, will not cause any interference in supersonic flow. The instrument was tested at Mach numbers ranging from 0.3 to 3.8. Use of the proper instrumentation and technique results in accuracy of the order of 1 percent.
A corona vacuum test facility for nondestructive testing of power system components was built in the Reliability and Quality Engineering Test Laboratories at the NASA Lewis Research Center. The facility was developed to simulate operating temperature and vacuum while monitoring corona discharges with residual gases. The facility is being used to test various high-voltage power system components.
The technical feasibility of using the corona discharge technique as a means for producing efficient silicon solar cells is elaborated.
In the Reliability and Quality Engineering Test Laboratory at the NASA Lewis Research Center a nondestructive, corona-vacuum test facility for testing power system components was developed using commercially available hardware. The test facility was developed to simulate operating temperature and vacuum while monitoring corona discharges with residual gases. This facility is being used to test various high voltage power system components.
The report supplies the theoretical background and design techniques needed by an engineer who is designing electrical insulation for high-voltage high-power components, equipment, and systems on aircraft. A literature survey and abundant bibliography identify references that provide further data on the subjects of partial discharges, corona, field theory and plotting, voids and processes for applying insulation. Both gaseous and solid insulations are treated. Cryogenic and liquid design notes are included. Tests and test equipment for high voltage insulation and equipment are defined. Requirements of test plans and procedures for high-voltage high-power equipment are identified and illustrated by examples. Suggestions for high-voltage specifications are provided. Very few of the Military and Government specifications deal with system voltages above 10kv, thus most aircraft high-voltage specifications will have to be derived from the power industry specifications and standards produced by ASTM, IEEE, and NEMA.
Commercially available corona discharge ozone generator, fitted onto industrial cooling tower, significantly reduces formation of scales (calcium carbonate) and corrosion. System also controls growth of algae and other microorganisms. Modification lowers cost and improves life of cooling system.
Electrical feedthrough connects both low-voltage and high-voltage signals between cryogenic environment and "outside world." Developed for cooled germanium gamma-ray detector, feedthrough has especially low capacitance and low sensitivity to microphonic noise. Its high-voltage lead is free of corona discharge and electrical breakdown to at least 5 kV.
An introduction to the theory of corona discharge and electrostatic phenomena is presented. The theory is mainly qualitative so that workers in the field should not have to go outside this manual for an understanding of the relevant phenomena. Some of the problems that may occur with the space shuttle in regard to electrical discharge are discussed.
This report supplies the theoretical background and design techniques needed by an engineer who is designing electrical insulation for high-voltage, high-power components, equipment, and systems for aircraft. A literature survey and abundant bibliography identify references that provide further data on the subjects of partial discharges, corona, field theory and plotting, voids and processes for applying insulation. Both gaseous and solid insulations are treated. Cryogenic and liquid design notes are included. Tests and test equipment for high voltage insulation and equipment are defined. Requirements of test plans and procedures for high-voltage, high-power equipment are identified and illustrated by examples. Suggestions for high-voltage specifications are provided. Very few of the Military and Government specifications deal with system voltages above 10kV, thus most aircraft high-voltage specifications will have to be derived from the power industry specifications and standards produced by ASTM, IEEE, and NEMA.
The charged particle generator was further tested after some design modification. The generator performance was measured with additional instrumentation and found to confirm previous measurements. Plans for a field testing were than developed. The overall status of the program and the field test plans were presented to a group of atmospheric scientists and electrostatic experts at the NASA/MSFC sponsored USRA Workshop on Electrostatic Fog Dispersal at NCAR, Boulder, Colorado discussed in previous sections. The recommendations from this workshop are being evaluated as to whether NASA should proceed with the field test or whether further theoretical research on the phenomenon of electrostatic fog dispersal and additional development of the charged particle generator should be carried out. Information obtained from the USRA Workshop clearly identified three physical mechanisms that could possibly influence the fog dispersal process, which heretofore have not been considered, and which may provide additional insight to the direction of further fog dispersal work. These mechanisms are: the effect of corona discharge on the electric field strength at the surface, the influx of fog into the cleared volume by turbulent diffusion, and the increase in supersaturation as liquid water is removed, activating haze particles, and thus generating more fog. Plans are being formulated to investigate these mechanisms.
It is proposed that the AIB amino acid at the K/T boundary were synthesized during entry of a comet. However, whether they were synthesized or supplied directly from space, the concentration of amino acids in the shallow K/T sea would have been about 10(exp -7) M. It is probable that clays were the dominant sinks for the amino acids in the K/T sea and in the primordial ocean. Because clay removed amino acids from sea water quickly, the amino acid contribution must be studied from individual comets in order to evaluate the effectiveness of comets for chemical evolution. Such an evaluation shows that comets would have produced amino acid concentration higher than equilibrium concentrations of amino acid from corona discharge at all times preceding the age of the oldest fossils. The perferred sites for chemical evolution of cometary amino acids are in cloud drops and tide pools where the concentration of amino acids would have been the highest. Life could have originated at the surface even during periods of intense bombardment of the earth before 3.8 billion years ago.
It is proposed that the AIB amino acids at the K/T boundary were synthesized during entry of a comet. However, whether they were synthesized or supplied directly from space, the concentration of amino acids in the shallow K/T sea would have been about 10(exp -7) M. It is probable that clays were the dominant sinks for the amino acids in the K/T sea and in the primordial ocean. Because clay removed amino from the sea so quickly, we must study the amino acid contribution from individual comets in order to evaluate the effectiveness of comets for chemical evolution. Such an evaluation shows that comets would have produced amino acid concentrations higher than equilibrium concentrations of amino acids from corona discharge at all times preceding the age of the oldest fossils. The preferred sites for chemical evolution of cometary amino acids are in cloud drops and tide pools where the concentration of amino acids would have been the highest. Life could have originated at the surface even during periods of intense bombardment of the earth before 3.8 billion years ago.
Two assemblies of laboratory equipment developed for use in testing abilities of polymers, paints, and other materials to withstand ultraviolet radiation and charged particles. One is vacuum ultraviolet source built around commercial deuterium lamp. Other exposes specimen in partial vacuum to both ultraviolet radiation and brush corona discharge. Either or both assemblies used separately or together to simulate approximately combination of solar radiation and charged particles encountered by materials aboard spacecraft in orbit around Earth. Also used to provide rigorous environmental tests of materials exposed to artificial ultraviolet radiation and charged particles in industrial and scientific settings or to natural ultraviolet radiation and charged particles aboard aircraft at high altitudes.
Amino acids yields for previously published shock tube experiments are used with minimum Cretaceous-Tertiary (K/T) impactor mass and comet composition to predict AIB amino acid K/T boundary sediment column density. The inferred initial concentration of all amino acids in the K/T sea and in similar primordial seas just after 10 km comet impacts would have been at least 10 exp -7 M. However, sinks for amino acids must also be considered in calculating amino acid concentrations after comet impacts and in assessing the contribution of comets to the origin of life. The changing concentration of cometary amino acids due to ultraviolet light is compared with the equilibrium concentration of amino acids produced in the sea from corona discharge in the atmosphere, deposition in water, and degradation by ultraviolet light. Comets could have been more important than endogenous agents for initial evolution of amino acids. Sites favorable for chemical evolution of amino acids are examined, and it is concluded that chemical evolution could have occurred at or above the surface even during periods of intense bombardment of earth before 3.8 billion years ago.
The present volume on fiber-optic and laser sensors discusses industrial applications of fiber-optic sensors, fiber-optic temperature sensors, fiber-optic current sensors, fiber-optic pressure/displacement/vibration sensors, and generic fiber-optic systems. Attention is given to a fiber-sensor design for turbine engines, fiber-optic remote Fourier transform IR spectroscopy, near-IR fiber-optic temperature sensors, and an intensity-type fiber-optic electric current sensor. Topics addressed include fiber-optic magnetic field sensors based on the Faraday effect in new materials, diaphragm size and sensitivity for fiber-optic pressure sensors, a microbend pressure sensor for high-temperature environments, and linear position sensing by light exchange between two lossy waveguides. Also discussed are two-mode elliptical-core fiber sensors for measurement of strain and temperature, a fiber-optic interferometric X-ray dosimeter, fiber-optic interferometric sensors using multimode fibers, and optical fiber sensing of corona discharges.
A system was developed for subjecting plants to elevated air ion levels. This system consisted of a rectangular Plexiglas chamber lined with a Faraday cage. Air ions were generated by corona discharge from frayed stainless steel fibers placed at one end of the chamber. This source was capable of producing varying levels of either positive or negative air ions. During plant exposures, environmental conditions were controlled by operating the unit in a growth chamber.
The NASA Glenn Research Center, partner universities, and defense contractors are working to develop intelligent power management and distribution (PMAD) technologies for future spacecraft and launch vehicles. The goals are to provide higher performance (efficiency, transient response, and stability), higher fault tolerance, and higher reliability through the application of digital control and communication technologies. It is also expected that these technologies will eventually reduce the design, development, manufacturing, and integration costs for large, electrical power systems for space vehicles. The main focus of this research has been to incorporate digital control, communications, and intelligent algorithms into power electronic devices such as direct-current to direct-current (dc-dc) converters and protective switchgear. These technologies, in turn, will enable revolutionary changes in the way electrical power systems are designed, developed, configured, and integrated in aerospace vehicles and satellites. Initial successes in integrating modern, digital controllers have proven that transient response performance can be improved using advanced nonlinear control algorithms. One technology being developed includes the detection of "soft faults," those not typically covered by current systems in use today. Soft faults include arcing faults, corona discharge faults, and undetected leakage currents. Using digital control and advanced signal analysis algorithms, we have shown that it is possible to reliably detect arcing faults in high-voltage dc power distribution systems (see the preceding photograph). Another research effort has shown that low-level leakage faults and cable degradation can be detected by analyzing power system parameters over time. This additional fault detection capability will result in higher reliability for long-lived power systems such as reusable launch vehicles and space exploration missions.