Heat sterilizable and impact resistant Ni-Cd battery development Quarterly report, 1 Jul. - 30 Sep. 1969
Heat sterilization and impact resistent Ni-Cd battery development
Popat, P. V.↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Determination of the E2/M1 multipole mixing ratios of the gamma transitions in Cd 110
E2/M1 multipole mixing ratios of gamma transitions in Cd 110
Krane, K. S.↗
Probabilities for radiation and predissociation. II - The excited states of CH, CD, and CH/plus/, and some astrophysical implications
CH, CD and CH ion excited states decay rates determined from phase shift and frequency data, discussing implications for astrophysics
Hesser, J. E.↗
Study to improve the low frequency noise characteristics of (Hg,Cd)Te detectors
Efforts made to identify and reduce the sources of l/f noise in 15 micron n-type (Hg,Cd)Te detectors operating at 77 K are reported. The investigation covered: evaluation of the influence of material properties and detector processing techniques, determination of the relative importance of surfaces, volumes, regions, and contracts, and generation of theoretical models for guidance of the experimental work.
Broudy, R. M.↗
An evaluation of potentially useful separator materials for nickel-cadmium (Ni-Cd] satellite batteries
An evaluation intended to determine the potential suitability and probable efficacy of a group of separator materials for use in nickel-cadmium (Ni-Cd) satellite batteries was carried out. These results were obtained using test procedures established in an earlier evaluation of other separator materials, some of which were used in experimental battery cells subjected to simulated use conditions. The properties that appear to be most important are: high electrolyte absorptivity, good electrolyte retention, low specific resistivity, rapid wettability and low resistance to air permeation. Wicking characteristics and wet-out time seem to be more important with respect to the initial filling of the battery with the electrolyte.
Baker, H. A.↗
The detection of extended X-ray emission surrounding cD galaxies in poor clusters
The paper presents some preliminary results of a survey, performed with an imaging proportional counter, to detect X-ray emission from poor clusters which nevertheless contain dominant D or cD galaxies and could, therefore, be classified as Bautz-Morgan Type I. The data suggest that poor clusters can collect enough gas to become detectable X-ray sources if they are relatively compact, which the presence of dominant galaxies indicates.
Kriss, G. A.↗
Defect chemistry and characterization Hg(1-x)Cd(x)Te
Iodine doped single crystal samples of mercury cadmium telluride were annealed at temperatures varying from 450 C to 600 C in Hg vapor and quenched to room temperature. Hall effect measurements at 77 K on the crystals cooled to room temperature indicate the samples to be n-type after anneals at high Hg pressures whereas they turn p-type after anneals at low Hg pressures; the electron concentration increases with increase in Hg pressure. The results are explained on the basis that the crystals are saturated with (Hg,Cd)I2, with a fraction of the iodine being present as donor occupying tellurium lattice sites and a fraction being present as acceptors resulting from the iodine on tellurium lattice sites pairing with the doubly ionized native acceptor defects. The solubility of the donor species increases with increase in Hg pressure, whereas that of the acceptor species increases with decrease in Hg pressure. Equilibrium constants for the incorporation of the iodine species as well as the pairing reaction were established.
Vydyanath, H. R.↗
On the nature of the nova-like variable CD-42 deg 14462
Low dispersion long and short wavelength IUE spectra of the nova like system CD-42 deg 14462 were obtained on August 24 U.T. The short wave spectrum exhibits absorption features due to C III (lambda 1175), Lalpha 1216), NV (lambda1240), HeII (lambda 1640), SiIV (lambda1394), NIV (lambda1875) with CIV (lambda1550) as a P Cygni feature with blue shifted absorption suggesting the presence of material leaving the system. Possible interpretations of this object are discussed.
Guinan, E. F.↗
A search for neutral hydrogen in D and cD galaxies
Recent X-ray spectroscopic results suggest that 2-3 solar masses/yr of cooling gas may be falling into M87 and as much as 300 solar masses/yr into giant galaxies in rich clusters. The eventual fate of the gas in the radiatively accreting flow is an open question. In an attempt to set some bounds on the evolution of the gas, a sensitive search was performed for H I in a sample of eight D and cD galaxies in rich and poor clusters. Null detections in all cases set upper limits of (4-20) x 10 to the 8th solar masses of H I in the giant galaxies. Possible reasons for these nondetections and alternative evolutionary fates for the accreting gas are discussed.
Burns, J. O.↗
Defect chemistry and characterization of (Hg, Cd)Te
Single crystal samples of phosphorus doped Hg sub 0.8 Cd sub 0.2 Te were anneald at temperatures varying from 450 C to 600 C in various Hg atmospheres. The samples were quenched to room temperature from the annealing temperatures. Hall effect and mobility measurements were performed at 77 K on all these samples. The results indicate the crystals to be p type for a total phosphorus concentration of 10 to the 19th power/cu cm in all the samples. The hole concentration at 77 K increases with increasing Hg pressures at 450 C and 500 C contrary to the observation in undoped crystals. Also, at low Hg pressures the concentration of holes in the phosphorus doped crystals is lower than in the undoped crystals. The hole concentration in all the samples is lower than the intrinsic carrier concentration at the annealing temperatures. The hole mobility in the doped crystals is similar to that in the undoped crystals. A defect model according to which phosphorus behaves as a single acceptor interstitially, occupying Te lattice sites while it acts as a single donor occupying Hg lattice sites was established. Equilibrum constants established for the incorporation of all the phosphorus species explain the experimental results
Vydyanath, H. R.↗
Defect chemistry and characterization of Hg sub 1x Cd sub x Te
Single crystal samples of undoped and doped Hg sub 1-x Cd sub x Te were annealed at varying temperatures and partial pressures of Hg. Hall effect and mobility measurements were carried out on these samples after quenching to room temperature. Based on the variation of the carrier concentration and the carrier mobility as a function of the partial pressure of Hg temperature, and dopant concentration, defect models were established for the doped and the undoped crystals. These models indicate that the native acceptor defects in both Hg0.8Cd0.2Te and Hg0.6Cd0.4Te doubly ionized and the native donor defects are negligible in concentration, implying that p to n conversion in these alloys occurs due only to residual donors. Incorporation mechanism of copper, indium, iodine, and phosphorus were investigated. A large concentration of indium is found to be paired with the native acceptor defects. Results on crystals doped with phosphorus indicate that phosphorus behaves amphoterically, acting as a donor on Hg lattice sites and as an acceptor intersitially on Te lattice sites. A majority of the phosphorus is found to be present as neutral species formed from the pairing reaction between phosphorus on Hg lattice sites and phosphorus in interstitial sites. Equilibrium constants for the intrinsic excitation reaction, as well as for the incorporation of the different dopants and the native acceptor defects were established.
Vydyanath, H. R.↗
Performance of a 2D-CD nonaxisymmetric exhaust nozzle on a turbojet engine at altitude
Baseline thrust and cooling data obtained with a 2D-CD versatile research exhaust nozzle mounted on a turbojet engine in an altitude chamber are presented. The tests covered a range of nozzle pressure ratios, nozzle pressure ratios, nozzle throat areas, and internal expansion area ratios. The thrust data obtained show good agreement with theory and scale model results after correcting the data for leakage and bypass cooling flows. Additional work is needed to improve predictability of cooling performance.
Straight, D. M.↗
Determination of the reliability of Ni-Cd batteries from survival data on cells fabricated 1964 - 1977
The probability of Ni-Cd battery survival was determined by researching survival data on cells fabricated from 1964-1977. A log of cell failure times were plotted against cumulative failure percentage and mean and standard deviation were determined.
Jordan, A. S.↗
Directional solidification and characterization of Hg(1-x)Cd(x)Te alloys
A series of Hg(1-x)Cd(x)Te alloy crystals was grown by high temperature gradient directional solidification at furnace translation rates ranging from 0.068 to 1.12 microns/s. For several ingots, the measured longitudinal compositional profiles were fitted to theoretical profiles to estimate the magnitude of D, the liquid HgTe-CdTe interdiffusion coefficient. The best-fit value of D was about 550,000 sq cm/s. The majority of the ingots showed significant radial compositional variations along the growth axis. These variations are attributed, at least in part, to fluid flows ahead of the growth interface. The results are discussed in terms of the heat transfer characteristics of the alloy/ampule/furnace system, and on the effects of these characteristics on the shape and stability of the growth interface in a 1-g environment.
Lehoczky, S. L.↗
Electrical characterization of Hg(1-x)Cd(x)Te alloys
Theoretical models are described for calculations of charge-carrier concentrations, Fermi energy, and conduction electron mobility as functions of x, temperature, and ionized and neutral defect concentrations of Hg(1-x)Cd(x)Te alloys. Measurements are reported of electron concentration and electron mobility from 5-300 K for alloys with x values of between 0.17 and 0.30. The electrical data are in reasonable agreement with theory, and were analyzed to obtain estimates of donor and acceptor state concentrations. The electron mobilities are calculated in terms of a microscopic theory of electrical conduction derived from the solution of the Boltzmann equation for the perturbed steady-state electron distribution function, and they show that longitudinal optical-phonon and charged and neutral defect scattering are the dominant mobility-limiting mechanisms.
Lehoczky, S. L.↗
Measured thermal diffusivity of Hg(1-x)Cd(x)Te solids and melts
The thermal diffusivity of Hg(1-x)Cd(x)Te melts is found to rise rapidly with temperature to values characteristic of metals. Solid and melt diffusivities for values of x from 0 to 0.3 and over a temperature range from 150 to 900 C have been determined by the laser flash method of Parker, Taylor, and Cowan. The diffusivity decreases from a maximum at x = 0 in both the solid and the liquid, with the values observed at x = 0.3 being about 40 percent of those for x = 0. The solid diffusivity for x = 0 is 1.7 sq mm/s at 150 C, decreasing to 0.7 sq mm/s at the melting point. The x = 0 liquid diffusivity increases from 0.7 sq mm/s at the melting point to 3.5 sq mm/s at 900 C.
Holland, L. R.↗
Liquidus temperatures of Hg-rich Hg-Cd-Te alloys
Measurements are made of the liquidus temperatures for ten (Hg/1-x/Cd)Te/1-y/ compositions in which x ranges from 0.091 to 0.401 and y ranges from 0.544 to 0.952. It is found that for metal-rich melts with the same x value, the liquidus temperature increases with y when y is in the range 0.5-0.7. This behavior is explained by the higher degree of association between Cd and Te than between Hg and Te in the melts. It is noted that recent calculated values of the liquidus isotherms by Tung et al. (1982) are in fair to good agreement with the experimental results obtained here.
Szofran, F. R.↗
Design, development, performance, and reconditioning of Ni-Cd batteries using polyropylene separators
A performance assessment is made for the Viking Mars Lander Program's sealed, sterilizable, 8-ampere hour Ni-Cd batteries, which use a nonwoven polypropylene separator material. Attention is given to separator wettability, the optimization of electrolyte quantity, and the reduction of plate carbonate, in view of thermal considerations and other environmental design and test requirements generated by mission characteristics. Life data based on mission experience identify, in addition to performance and degradation behavior, a series of shallow discharge reconditioning cycles and an intensive program of deep discharge reconditioning.
Britting, A. O., Jr.↗