Nickel-hydrogen cell low-Earth life test update

When individual pressure vessel (IPV) nickel-hydrogen (Ni/H2) cells were selected as the energy storage system for the Space Station Freedom in March of 1986, a limited database existed on life and performance characteristics of these cells in a low earth orbit (LEO) regime. Therefore, NASA LeRC initiated a Ni/H2 cell test program with the primary objectives of building a test facility, procuring cells from existing NASA contracts, and screening several cell designs by life testing in a LEO 35 percent depth of discharge (DOD) scenario. A total of 40 cells incorporating 13 designs were purchased from Yardney, Hughes, and Eagle-Picher. Thirty-two of the cells purchased were 65 A-hr nameplate capacity and eight cells were 50 A-hr. Yardney and Eagle-Picher cells were built with both the Air Force recirculating and the advanced back-to-back electrode stack configurations and incorporated 31 and 26 percent KOH. Acceptance testing of the first delivered cells began in March of 1988, with life testing following in September of that year.Performance comparisons of these cells are made here while specifically addressing life test data relative to the design differences

Basic statistical analyses of candidate nickel-hydrogen cells for the Space Station Freedom

Nickel-Hydrogen (Ni/H2) secondary batteries will be implemented as a power source for the Space Station Freedom as well as for other NASA missions. Consequently, characterization tests of Ni/H2 cells from Eagle-Picher, Whittaker-Yardney, and Hughes were completed at the NASA Lewis Research Center. Watt-hour efficiencies of each Ni/H2 cell were measured for regulated charge and discharge cycles as a function of temperature, charge rate, discharge rate, and state of charge. Temperatures ranged from -5 C to 30 C, charge rates ranged from C/10 to 1C, discharge rates ranged from C/10 to 2C, and states of charge ranged from 20 percent to 100 percent. Results from regression analyses and analyses of mean watt-hour efficiencies demonstrated that overall performance was best at temperatures between 10 C and 20 C while the discharge rate correlated most strongly with watt-hour efficiency. In general, the cell with back-to-back electrode arrangement, single stack, 26 percent KOH, and serrated zircar separator and the cell with a recirculating electrode arrangement, unit stack, 31 percent KOH, zircar separators performed best

Solid Fuel Delivery System Developed for Combustion Testing on the International Space Station

NASA initiated Bioastronautics and Human Research Initiatives in 2001 and 2003, respectively, to enhance the safety and performance of humans in space. The Flow Enclosure Accommodating Novel Investigations in Combustion of Solids (FEANICS) is a multiuser facility being built at the NASA Glenn Research Center to advance these initiatives by studying fire safety and the combustion of solid fuels in the microgravity environment of the International Space Station (ISS). One of the challenges for the FEANICS team was to build a system that allowed for several consecutive combustion tests to be performed with minimal astronaut crew interaction. FEANICS developed a fuel carousel that contains a various number of fuel samples, depending on the fuel width, and introduces them one at a time into a flow tunnel in which the combustion testing takes place. This approach will allow the science team to run the experiments from the ground, while only requiring the crew to change out carousels after several tests have been completed

Hypervelocity Impact Testing of Nickel Hydrogen Battery Cells

Nickel-Hydrogen (Ni/H2) battery cells have been used on several satellites and are planned for use on the International Space Station. In January 1992, the NASA Lewis Research Center (LeRC) conducted hypervelocity impact testing on Ni/H2 cells to characterize their failure modes. The cell's outer construction was a 24 mil-thick Inconel 718 pressure vessel. A sheet of 1.27 cm thick honeycomb was placed in front of the battery cells during testing to simulate the on-orbit box enclosure. Testing was conducted at the NASA White Sands Test Facility (WSTF). The hypervelocity gun used was a 7.6 mm (0.30 caliber) two-stage light gas gun. Test were performed at speeds of 3, 6, and 7 km/sec using aluminum 2017 spherical particles of either 4.8 or 6.4 mm diameter as the projectile. The battery cells were electrically charged to about 75 percent of capacity, then back-filled with hydrogen gas to 900 psi simulating the full charge condition. High speed film at 10,000 frames/sec was taken of the impacts. Impacts in the dome area (top) and the electrode area (middle) of the battery cells were investigated. Five tests on battery cells were performed. The results revealed that in all of the test conditions investigated, the battery cells simply vented their hydrogen gas and some electrolyte, but did not burst or generate any large debris fragments

ARES I Upper Stage Subsystems Design and Development

From 2005 through early 2011, NASA conducted concept definition, design, and development of the Ares I launch vehicle. The Ares I was conceived to serve as a crew launch vehicle for beyond-low-Earth-orbit human space exploration missions as part of the Constellation Program Architecture. The vehicle was configured with a single shuttle-derived solid rocket booster first stage and a new liquid oxygen/liquid hydrogen upper stage, propelled by a single, newly developed J-2X engine. The Orion Crew Exploration Vehicle was to be mated to the forward end of the Ares I upper stage through an interface with fairings and a payload adapter. The vehicle design passed a Preliminary Design Review in August 2008, and was nearing the Critical Design Review when efforts were concluded as a result of the Constellation Program s cancellation. At NASA Glenn Research Center, four subsystems were developed for the Ares I upper stage. These were thrust vector control (TVC) for the J-2X, electrical power system (EPS), purge and hazardous gas (P&HG), and development flight instrumentation (DFI). The teams working each of these subsystems achieved 80 percent or greater design completion and extensive development testing. These efforts were extremely successful representing state-of-the-art technology and hardware advances necessary to achieve Ares I reliability, safety, availability, and performance requirements. This paper documents the designs, development test activity, and results

Reynolds Number Effects at High Angles of Attack

Lessons learned from comparisons between ground-based tests and flight measurements for the high-angle-of-attack programs on the F-18 High Alpha Research Vehicle (HARV), the X-29 forward-swept wing aircraft, and the X-31 enhanced fighter maneuverability aircraft are presented. On all three vehicles, Reynolds number effects were evident on the forebodies at high angles of attack. The correlation between flight and wind tunnel forebody pressure distributions for the F-18 HARV were improved by using twin longitudinal grit strips on the forebody of the wind-tunnel model. Pressure distributions obtained on the X-29 wind-tunnel model at flight Reynolds numbers showed excellent correlation with the flight data up to alpha = 50 deg. Above (alpha = 50 deg. the pressure distributions for both flight and wind tunnel became asymmetric and showed poorer agreement, possibly because of the different surface finish of the model and aircraft. The detrimental effect of a very sharp nose apex was demonstrated on the X-31 aircraft. Grit strips on the forebody of the X-31 reduced the randomness but increased the magnitude of the asymmetry. Nose strakes were required to reduce the forebody yawing moment asymmetries and the grit strips on the flight test noseboom improved the aircraft handling qualities

Measurements of inclusive and differential fiducial cross-sections of tt production with additional heavy-flavour jets in proton-proton collisions at √ s= 13 TeV with the ATLAS detector

This paper presents measurements of tt production in association with additional b-jets in pp collisions at the LHC at a centre-of-mass energy of 13 TeV. The data were recorded with the ATLAS detector and correspond to an integrated luminosity of 36.1 fb−1. Fiducial cross-section measurements are performed in the dilepton and lepton-plus-jets tt decay channels. Results are presented at particle level in the form of inclusive cross-sections of tt final states with three and four b-jets as well as differential cross-sections as a function of global event properties and properties of b-jet pairs. The measured inclusive fiducial cross-sections generally exceed the ttbb predictions from various next-to-leading-order matrix element calculations matched to a parton shower but are compatible within the total uncertainties. The experimental uncertainties are smaller than the uncertainties in the predictions. Comparisons of state-of-the-art theoretical predictions with the differential measurements are shown and good agreement with data is found for most of them

Measurement of jet fragmentation in Pb+Pb and pp collisions at √s NN =5.02 TeV with the ATLAS detector

This paper presents a measurement of jet fragmentation functions in 0.49 nb −1 of Pb+Pb collisions and 25 pb −1 of pp collisions at √ sNN =5.02 TeV collected in 2015 with the ATLAS detector at the LHC. These measurements provide insight into the jet quenching process in the quark-gluon plasma created in the aftermath of ultra-relativistic collisions between two nuclei. The modifications to the jet fragmentation functions are quantified by dividing the measurements in Pb+Pb collisions by baseline measurements in pp collisions. This ratio is studied as a function of the transverse momentum of the jet, the jet rapidity, and the centrality of the collision. In both collision systems, the jet fragmentation functions are measured for jets with transverse momentum between 126 GeV and 398 GeV and with an absolute value of jet rapidity less than 2.1. An enhancement of particles carrying a small fraction of the jet momentum is observed, which increases with centrality and with increasing jet transverse momentum. Yields of particles carrying a very large fraction of the jet momentum are also observed to be enhanced. Between these two enhancements of the fragmentation functions a suppression of particles carrying an intermediate fraction of the jet momentum is observed in Pb+Pb collisions. A small dependence of the modifications on jet rapidity is observed

Search for Higgs bosons produced via vector-boson fusion and decaying into bottom quark pairs in √s =13 TeV pp collisions with the ATLAS detector

A search for the bb ¯ decay of the Standard Model Higgs boson produced through vector-boson fusion is presented. Three mutually exclusive channels are considered: two all-hadronic channels and a photon-associated channel. Results are reported from the analysis of up to 30.6 fb −1 of pp data at s √ =13 TeV collected with the ATLAS detector at the LHC. The measured signal strength relative to the Standard Model prediction from the combined analysis is 2.5 +1.4 −1.3 for inclusive Higgs boson production and 3.0 +1.7 −1.6 for vector-boson fusion production only

Search for heavy particles decaying into a top-quark pair in the fully hadronic final state in pp collisions at √s=13 TeV with the ATLAS detector

A search for new particles decaying into a pair of top quarks is performed using proton-proton collision data recorded with the ATLAS detector at the Large Hadron Collider at a center-of-mass energy of √s=13  TeV corresponding to an integrated luminosity of 36.1  fb−1. Events consistent with top-quark pair production and the fully hadronic decay mode of the top quarks are selected by requiring multiple high transverse momentum jets including those containing b-hadrons. Two analysis techniques, exploiting dedicated top-quark pair reconstruction in different kinematic regimes, are used to optimize the search sensitivity to new hypothetical particles over a wide mass range. The invariant mass distribution of the two reconstructed top-quark candidates is examined for resonant production of new particles with various spins and decay widths. No significant deviation from the Standard Model prediction is observed and limits are set on the production cross-section times branching fraction for new hypothetical Z′ bosons, dark-matter mediators, Kaluza-Klein gravitons and Kaluza-Klein gluons. By comparing with the predicted production cross sections, the Z′ boson in the topcolor-assisted-technicolor model is excluded for masses up to 3.1–3.6 TeV, the dark-matter mediators in a simplified framework are excluded in the mass ranges from 0.8 to 0.9 TeV and from 2.0 to 2.2 TeV, and the Kaluza-Klein gluon is excluded for masses up to 3.4 TeV, depending on the decay widths of the particles