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At least 505 records · Page 28

Measurements and monitoring of the hydrogen and deuterium contents in the plasma of the L-2M stellarator

The program of experiments on ITER includes a sequential change of the plasma isotopic composition from pure hydrogen plasma in the initial stage of research to deuterium and, then, deuterium-tritium plasma with a gradual increase in the tritium content. In this context, the influence of the plasma isotopic composition on the processes of plasma heating and confinement are being actively studied on the existing tokamaks and stellarators. The plasma isotopic composition also depends on the composition of the gas desorbed from the vacuum chamber wall in the course of recycling. Therefore, the rate of change of the plasma isotopic composition after altering the injected gas also depends on the rate of change of the isotopic composition of the gas absorbed in the wall. These effects were studied in the experiments carried out on the L-2M stellarator in which the working gas was changed from hydrogen to deuterium. Spectral measurements of the intensity ratio between the H{sub {alpha}} and D{sub {alpha}} lines made it possible to monitor the isotopic composition of the plasma in the course of cleaning of the chamber wall from earlier absorbed hydrogen and its replacement with deuterium. After returning to hydrogen, the rate of cleaning of the wall from deuterium was also determined. The results of these experiments show that the plasma isotopic composition varies exponentially with the number N of shots after transition to another isotope, {approx}exp(-N/47). Hence, the isotopic composition can be changed almost completely over 2 to 3 working days. This allows one to study the influence of the plasma isotopic composition on plasma confinement during the same experimental session.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

High Temperature Moderator Cladding Report

The hydrogen permeation system at LANL has been modified and improved to perform high temperature testing of metals and metal/ceramic samples. This will allow us to demonstrate the ability to reduce hydrogen permeation for microreactor materials. For this program, two metals have been chosen for analysis, stainless steel as a base metal and TZM based on its high temperature properties and anticipated higher H permeation resistance. Samples have been fabricated and coated with Al 2 O 3 via atomic layer deposition in order to evaluate the potential to reduce hydrogen permeation with a thin layer ceramic coating. Current efforts include literature review of systems and sample fabrication to demonstrate feasibility, future work will focus on collecting hydrogen permeation data.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

Hydrogen Peroxide-Water-Ethanol-Monopropellant Blend for CubeSat Propulsion

Monopropellant propulsion that provides high performance and low hazards compared to state-of-art hydrazine are being investigated under NASA, DOD and commercially sponsored green propellant research and development programs. This NASAeffort looks at phosphate stabilized 50% hydrogen peroxide/water –ethanol blends to evaluate their stability and combustion behavior in submillimeter diameter microtube combustion apparatus for cubesat propulsion applications. Exploratory 7-day stabilitytests find no pressure rise in a sealed test tube environment at room temperature indicating at least short term stability of the mixture. Temperature rise during combustion testing in resistively heated nickel microtube apparatus shows that micro-combustion is achieved in the tube. Propellant density is approximately 1.2 g/cm3compared to 1.0 g/cm3for hydrazine. Theoretical specific impulse of the stoichiometric blend is 219 s at a chamber pressure of 20 psia and an area ratio of 30:1. Density-specific impulseof this blendis263 swhile hydrazine is only about 215-220 sin small reaction control system thrusters. This provides about 20-22% more density-specific impulse for the cubesat compared to hydrazine. The theoreticalcombustion temperature is2168°F, whichis thermally compatible with stainless steel materials of constructionand the nickel catalystused in the tests. Combustion test results are given for stoichiometric, as well as fuel-leanand fuel-richpropellant formulations. Thesetests focus on thermally and catalytically supported combustionin the microtube, whichrequires a microtube preheat temperature of about 900°F and sufficient residence time to achieve combustion that is stable and anchored in the tubewithout blowing through the tube unreacted. Thrust class is expected to be in the 10 mN range based on flow rate and estimated specific impulse.Power requirements are generally below 25 Wto heat the tube. Steady state combustion testing is typically conducted for 3 minutes and shows littledegradation of the hardware over multiple test cyclesindicating thatthere is little catalyst degradation over time and littlecatalyst deactivation due tothe phosphate stabilizer inthe hydrogen peroxide.

Monopropellant↗

Computer program for thermodynamic analysis of open cycle multishaft power system with multiple reheat and intercool

A computer program to analyze power systems having any number of shafts up to a maximum of five is presented. On each shaft there can be as many as five compressors and five turbines, along with any specified number of intervening intercoolers and reheaters. A recuperator can be included. Turbine coolant flow can be accounted for. Any fuel consisting entirely of hydrogen and/or carbon can be used. The program is valid for maximum temperatures up to about 2000 K (3600 R). The system description, the analysis method, a detailed explanation of program input and output including an illustrative example, a dictionary of program variables, and the program listing are explained.

Glassman, A. J.↗

Inflation and Early Dark Energy with a Stage II Hydrogen Intensity Mapping experiment

This white paper envisions a revolutionary post-DESI, post-LSST dark energy program based on intensity mapping of the redshifted 21 cm emission line from neutral hydrogen out to redshift z ~ 6 at radio frequencies. The proposed intensity mapping survey has the unique capability to quadruple the volume of the Universe surveyed by optical programs, provide a percent-level measurement of the expansion history to z ~ 6, open a window to explore physics beyond the concordance {\\Lambda}CDM model, and to significantly improve the precision on standard cosmological parameters. In addition, characterization of dark energy and new physics will be powerfully enhanced by cross-correlations with optical surveys and cosmic microwave background measurements. The rich dataset obtained by the proposed intensity mapping instrument will be simultaneously useful in exploring the time-domain physics of fast radio transients and pulsars, potentially in live "multi-messenger" coincidence with other observatories. The core Dark Energy/Inflation science advances enabled by this program are the following: i) Measure the expansion history of the universe in the pre-acceleration era at the same precision as at lower redshifts, providing an unexplored window for new physics. ii) Observe, or constrain, the presence of inflationary relics in the primordial power spectrum, improving existing constraints by an order of magnitude; iii) Observe, or constrain, primordial non-Gaussianity with unprecedented precision, improving constraints on several key numbers by an order of magnitude. Detailed mapping of the enormous, and still largely unexplored, volume of space observable in the mid-redshift (z ~ 2 - 6) range will thus provide unprecedented information on fundamental questions of vacuum energy and early-universe physics.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Energy Arbitrage with Hydrogen: HTSE + Combustion Turbine

The Light Water Reactor Sustainability (LWRS) program seeks to keep Nuclear Power Plants (NPPs) competitive in the changing energy market. The Flexible Plant Operation and Generation (FPOG) pathway investigates Energy Storage Systems (ESS) to give operators an alternative to curtailment or paying to put power on the grid. This work investigates the concept of diverting heat and electricity to High Temperature Steam Electrolysis (HTSE) to produce hydrogen when grid demand is low, storing that hydrogen, then burning it in a combustion turbine to produce zero-emission electricity when grid demand is high. A process model of the combustion turbine was developed in Aspen HYSYS, which was used to complete a parametric analysis and techno-economic analysis.

08 HYDROGEN↗

An Interim Set of TNT Curves for LOX/LNG Explosions

Space launch companies are actively developing, or in some cases have already developed, new vehicles that use large quantities of liquid oxygen (LOX) and liquid natural gas (LNG) propellants. This propellant mixture currently lacks sound/verified explosive safety standards for use in explosive siting and flight safety analysis. In the U.S., multiple government and commercial organizations have conducted limited testing, or are preparing to conduct tests, intended to provide a sound technical basis for LOX/LNG explosive standards applicable to space launch vehicle ground and flight operations. The limited testing and analysis conducted so far indicates the potential to produce extremely energetic explosions due to the miscibility of LOX/LNG (methane), a unique feature relative to previously used propellant mixtures such as hydrogen/oxygen or kerosene/oxygen. MOX is a homogenous mixture of methane and oxygen that is possible because of methane’s 100% miscibility in LOX. Preliminary testing by N2L, Inc. described in this paper shows that it is possible to form MOX with a variety of mixing methods, and that MOX is a sensitive high explosive capable of producing overpressures greater than comparable masses of C-4. The limited amount and quality of large-scale LOX/LNG explosive test data, and the potential formation of high-explosive MOX, create significant unknowns in the determination of hazard areas (cleared of the public) for ground operations (such as a static fire test) and flights of launch vehicles with LOX/LNG propellant. This paper will review the methods used by NASA to develop and validate the LOX/LH2 blast model using large-scale explosive test programs such as Project PYRO, the Hydrogen-Oxygen Vertical Impact (HOVI), and the Large-Scale Hydrogen-Oxygen Explosion (LSHOE) tests. This paper will describe how the same process was used to prepare an interim LOX/LNG blast model that applies to various LV failure scenarios and conservatively accounts for potential MOX formation. This paper also summarizes past and future testing and modeling efforts funded by a consortium of NASA, the US Federal Aviation Administration (FAA), and the US Space Force (USSF). These test programs should be concluded within the next 3 years and are intended to provide empirical data for model verification and validation.

Liquid Oxygen↗

An Interim Set of TNT Curves for LOX/LNG Explosions

Space launch companies are actively developing, or in some cases have already developed, new vehicles that use large quantities of liquid oxygen (LOX) and liquid natural gas (LNG) propellants. This propellant mixture currently lacks sound/verified LOX/LNG explosive safety standards for use in explosive siting and flight safety analysis. In the U.S., multiple government and commercial organizations have conducted limited testing, or are preparing to conduct tests, intended to provide a sound technical basis for explosive standards applicable to space launch vehicle ground and flight operations. The limited testing and analysis conducted so far indicates the potential to produce extremely energetic explosions due to the miscibility of LOX/LNG (methane), a unique feature relative to previously used propellant mixtures such as hydrogen/oxygen or kerosene/oxygen. MOX is a homogenous mixture of methane and oxygen that is possible because of methane’s 100% miscibility in LOX. Preliminary testing by N2L, Inc. described in this paper shows that it is possible to form MOX with a variety of mixing methods, and that MOX is a sensitive high explosive capable of producing overpressures greater than comparable masses of C-4. The limited amount and quality of large-scale LOX/LNG explosive test data, and the potential formation of high-explosive MOX, create significant unknowns in the determination of hazard areas (cleared of the public) for ground operations (such as a static fire test) and flights of launch vehicles with LOX/LNG propellant. This paper will review the methods used by NASA to develop and validate the LOX/LH2 blast model using large-scale explosive test programs such as Project PYRO, the Hydrogen-Oxygen Vertical Impact (HOVI), and the Large-Scale Hydrogen-Oxygen Explosion (LSHOE) tests. This paper will describe how the same process was used to prepare an interim LOX/LNG blast model that applies to various LV failure scenarios and conservatively accounts for potential MOX formation. This paper also summarizes past and future testing and modeling efforts funded by a consortium of NASA, the US Federal Aviation Administration (FAA), and the US Space Force (USSF). These test programs should be concluded within the next 3 years and are intended to provide empirical data for model verification and validation.

Liquid Oxygen↗

Elucidating hydrogen isotope transport mechanisms in proton-conducting ceramics with trapping effects using TMAP8

Hydrogen isotopes play an central role in many science and engineering applications such as fuel cells, hydrogen production, and fusion energy. For these applications, hydrogen separation and extraction applications are pivotal aspects of hydrogen transports, where proton-conducting ceramics (PCCs) have shown great potential. In this study, we propose a new model for hydrogen isotope transport in PCC materials, BaZr 0.9 Y 0.1 O 2.95 (BZY) in particular, which captures behavior in both dry and wet environments. The model expands previous efforts and considers diffusion, trapping, and surface reactions (i.e., dissociation and recombination). We then validate and calibrate the model using deuterium transport measurements from experiments in both dry and wet environments. This study highlights the key role of trapping, often neglected, on hydrogen isotope transport in BZY and other PCC materials. It also explains how the commonly observed discrepancy between dry and wet behavior can be attributed to more active surface reactions and saturated traps due to the increased hydrogen presence under the wet environment. These results provide insights to optimize PCC manufacturing and usage as a hydrogen separation and extraction technology in various fields, emphasizing that lowering the trapping can reduce hydrogen isotope retention. These modeling and calibration efforts are performed using the tritium migration analysis program, version 8 (TMAP8), an open-source application designed for hydrogen isotope transport.

36 - MATERIALS SCIENCE↗

The Development of Silicon Carbide Based Hydrogen and Hydrocarbon Sensors

Silicon carbide is a high temperature electronic material. Its potential for development of chemical sensors in a high temperature environment has not been explored. The objective of this study is to use silicon carbide as the substrate material for the construction of chemical sensors for high temperature applications. Sensors for the detection of hydrogen and hydrocarbon are developed in this program under the auspices of Lewis Research Center, NASA. Metal-semiconductor or metal-insulator-semiconductor structures are used in this development. Specifically, using palladium-silicon carbide Schottky diodes as gas sensors in the temperature range of 100 to 400 C are designed, fabricated and assessed. The effect of heat treatment on the Pd-SiC Schottky diode is examined. Operation of the sensors at 400 C demonstrate sensitivity of the sensor to hydrogen and hydrocarbons. Substantial progress has been made in this study and we believe that the Pd-SiC Schottky diode has potential as a hydrogen and hydrocarbon sensor over a wide range of temperatures. However, the long term stability and operational life of the sensor need to be assessed. This aspect is an important part of our future continuing investigation.

Liu, Chung-Chiun↗

Cast iron-base alloy for cylinder/regenerator housing

NASACC-1 is a castable iron-base alloy designed to replace the costly and strategic cobalt-base X-40 alloy used in the automotive Stirling engine cylinder/generator housing. Over 40 alloy compositions were evaluated using investment cast test bars for stress-rupture testing. Also, hydrogen compatibility and oxygen corrosion resistance tests were used to determine the optimal alloy. NASACC-1 alloy was characterized using elevated and room temperature tensile, creep-rupture, low cycle fatigue, heat capacity, specific heat, and thermal expansion testing. Furthermore, phase analysis was performed on samples with several heat treated conditions. The properties are very encouraging. NASACC-1 alloy shows stress-rupture and low cycle fatigue properties equivalent to X-40. The oxidation resistance surpassed the program goal while maintaining acceptable resistance to hydrogen exposure. The welding, brazing, and casting characteristics are excellent. Finally, the cost of NASACC-1 is significantly lower than that of X-40.

Witter, Stewart L.↗

Recovery Act - PEM Fuel Cell Systems Providing Emergency Reserve and Backup Power (Final Technical Report)

The STI product is the Final Technical Report from ReliOn, Inc. for contract award DE-EE0000487: Recovery Act PEM Fuel Cell Systems Providing Emergency Reserve and Backup Power. The program covered the turnkey deployment of 431 ReliOn fuel cell systems at 189 individual sites for AT&T and PG&E with ReliOn functioning as the primary equipment supplier and the project manager. The Final Technical Report provides an executive level summary, a comparison of the actual accomplishments vs. the goals and objectives of the project, as well as a summary of the project activity from the contract award date of August 1, 2009 through the contract expiration date of December 31, 2011. Two photos are included in the body of the report which show hydrogen storage and bulk hydrogen refueling technologies developed as a result of this program.

08 HYDROGEN↗

Electrical enclosure hydrogen intrusion study

As a cost savings measure for the space shuttle program, the feasibility of substituting dry air for nitrogen as the purge gas used to minimize the probability of fire and explosions which could erupt from propellant vapor (hydrogen) diffusion into the electrical enclosures at Launch Complex 39 was investigated. It was concluded that: (1) Hydrogen concentrations of approximately 1% were obtained in an electrical enclosure under design purge conditions. (2) Hydrogen concentrations exceeding the lower explosive limit, 4%, could probably be obtained within the enclosure under worst case conditions. (3) Most of the hydrogen intrusion into the enclosure probably occurred at the point with the shortest leak path, such as the door seal. (4) More stringent electrical enclosure design requirements should be imposed before air is using as a purge gas.

Welch, P. J.↗

Cyclic-load crack growth in ASME SA-105 grade II steel in high-pressure hydrogen at ambient temperature

ASME SA-105 Grade II steel, which is used in high-pressure hydrogen compressor systems, is similar to steels used or considered for use in high-pressure hydrogen storage vessels and pipelines. This paper summarizes the results of a program conducted to provide cyclic-load crack growth rate (da/dN) data for a fracture mechanics analysis of a 15,000 psi hydrogen compressor facility which contains pulse quieter and after-cooler separator vessels constructed of the ASME SA-105 Grade II steel. Included in the program were tests performed to assist in establishing operating procedures that could minimize the effect of hydrogen on crack growth rates during operation.

Walter, R. J.↗

The ratio of deuterium to hydrogen in interstellar space. III - The lines of sight to Zeta Puppis and Gamma Cassiopeiae

An extensive set of measurements of the ratio of deuterium to hydrogen in the interstellar medium has been undertaken. The general observing program is described along with the data reduction techniques used to separate the complex deuterium and hydrogen profiles, and the results of the measurements for two stars, Zeta Pup and Gamma Cas. For Gamma Cas, log N(D)/N(H) is found to be approximately -4.8, in agreement with previous measurements. For Zeta Pup, a complicated structure of absorbing clouds in the interstellar medium is inferred. The best value of log N(D)/N(H) is about -4.6 for each of two components. One component is probably more complex than can be demonstrated directly at the resolution employed, and log N(D)N(H) could be -4.0 or larger in this component.

Vidal-Madjar, A.↗

Center for High-Efficiency Electrical Technologies for Aircraft (CHEETA)

The aeronautics industry has been challenged on many fronts to increase efficiency, reduce emissions, and decrease dependency on carbon-based fuels. With subsonic transports serving as the dominant contributor to the fuel consumption and carbon footprint of global aviation, the need for environmentally-responsible transportation has been met with a boom of research in the field of aircraft propulsion electrification across industry, government, and academic organizations. However, adoption of electrified propulsion systems for large commercial aircraft today is unattainable, due to the lack of motors and power electronics appropriately sized for these vehicles, high weight requirements of conventional electrical energy storage systems, and new principles required to design these classes of aircraft. The mission of the Center for High-Efficiency Electrical Technologies for Aircraft (CHEETA) program is to develop, mature, and design disruptive technologies for electric commercial aviation. The associated technologies being researched include distributed aero-propulsion system integration, high-efficiency electrochemical power conversion, flight-weight electric machines and power electronics, materials and systems for superconducting high-efficiency power transmission, and methods for complex system integration and optimization. Additionally, the current program is investigating the use of unconventional energy storage and power generation architectures, such as liquid hydrogen fuel and high-efficiency fuel cell systems. The research program provides a direct line-of-sight to not only achieving, but potentially even exceeding the aviation community goals for transition to alternative propulsion and energy through convergence of various novel technologies. The end result of maturation and integration of these technologies is an aircraft system with a quiet, efficient propulsion system that produces zero carbon dioxide, nitrogen oxides, and particulate matter emissions at the vehicle level.

Koushik Datta↗

An assessment of the government liquid hydrogen requirements for the 1995-2005 time frame including addendum, liquid hydrogen production and commercial demand in the United States

Liquid hydrogen will continue to be an integral element in virtually every major space program, and it has also become a significant merchant product for certain commercial markets. Liquid hydrogen is not a universally available commodity, and the number of supply sources historically have been limited to regions having concentrated consumption patterns. With the increased space program activity it becomes necessary to assess all future programs on a collective and unified basis. An initial attempt to identify projected requirements on a long range basis is presented.

Bain, Addison↗