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At least 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
NASA NTRS2008

Airborne Carbon Dioxide Laser Absorption Spectrometer for IPDA Measurements of Tropospheric CO2: Recent Results

The National Research Council's decadal survey on Earth Science and Applications from Space[1] recommended the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission for launch in 2013-2016 as a logical follow-on to the Orbiting Carbon Observatory (OCO) which is scheduled for launch in late 2008 [2]. The use of a laser absorption measurement technique provides the required ability to make day and night measurements of CO2 over all latitudes and seasons. As a demonstrator for an approach to meeting the instrument needs for the ASCENDS mission we have developed the airborne Carbon Dioxide Laser Absorption Spectrometer (CO2LAS) which uses the Integrated Path Differential Absorption (IPDA) Spectrometer [3] technique operating in the 2 micron wavelength region.. During 2006 a short engineering checkout flight of the CO2LAS was conducted and the results presented previously [4]. Several short flight campaigns were conducted during 2007 and we report results from these campaigns.

lidar↗
NASA NTRS2013

Miniaturized Laser Heterodyne Radiometer for Measurements of CO2 in the Atmospheric Column

We have developed a low-cost, miniaturized laser heterodyne radiometer for highly sensitive measurements of carbon dioxide (CO2) in the atmospheric column. In this passive design, sunlight that has undergone absorption by CO2 in the atmosphere is collected and mixed with continuous wave laser light that is step-scanned across the absorption feature centered at 1,573.6 nm. The resulting radio frequency beat signal is collected as a function of laser wavelength, from which the total column mole fraction can be de-convolved. We are expanding this technique to include methane (CH4) and carbon monoxide (CO), and with minor modifications, this technique can be expanded to include species such as water vapor (H2O) and nitrous oxide (N2O).

CO2↗
NASA NTRS2017

Zeolite Degradation: An Investigation of CO2 Capacity Loss of 13x Sorbent

System testing of the Carbon Dioxide Removal and Compression System (CRCS) has revealed that sufficient CO2 removal capability was not achieved with the designed system. Subsystem component analysis of the zeolite bed revealed that the sorbent material suffered significant degradation and CO2 loading capacity loss. In an effort to find the root cause of this degradation, various factors were investigated to try to reproduce the observed performance loss. These factors included contamination by vacuum pump oil, o-ring vacuum grease, loading/unloading procedures, and operations. This paper details the experiments that were performed and their results.

Air Revitalization↗
NASA NTRS2017

CO2 Capacity Sorbent Analysis Using Volumetric Measurement Approach

In support of air revitalization system sorbent selection for future space missions, Ames Research Center (ARC) has performed CO2 capacity tests on various solid sorbents to complement structural strength tests conducted at Marshall Space Flight Center (MSFC). The materials of interest are: Grace Davison Grade 544 13X, Honeywell UOP APG III, LiLSX VSA-10, BASF 13X, and Grace Davison Grade 522 5A. CO2 capacity was for all sorbent materials using a Micromeritics ASAP 2020 Physisorption Volumetric Analysis machine to produce 0C, 10C, 25C, 50C, and 75C isotherms. These data are to be used for modeling data and to provide a basis for continued sorbent research. The volumetric analysis method proved to be effective in generating consistent and repeatable data for the 13X sorbents, but the method needs to be refined to tailor to different sorbents.

Air Revitalization↗
NASA NTRS1971

The photolysis of CO2 at 1849 and 2139A

The quantum yield for CO2 photodissociation at 25 C was found to be 1.08 + or - 0.12 for direct photolysis at 1849 A and between 200 and 800 torr; 0.48 + or - 0.02 for the Hg 6(1 P 1) sensitized decomposition between 130 and 730 torr; and 0.16 + or - 0.05 for the direct photolysis at 2139 A and between 300 and 600 torr. At these wavelengths, there was insufficient energy found to produce O(1 D). The primary process used is CO2 + hv yields CO + O(3 P).

Krezenski, D.↗
NASA NTRS1972

Computer-aided CO2 laser cavity-length selection for reduced line competition

The advantages of carbon dioxide lasers for space communications systems are considered. An attempt was made to predict the signature of CO2 lasers. It was found that this requires accurate data on the laser wavelengths (accuracy on the order of 10 MHz). The results of absolute frequency measurements of CO2 lines were utilized, and a list of accurate frequencies was calculated. A computer program was written for the signature prediction. A second program was written which searches through large ranges of cavity length and prints lists of regions where a particular line is well separated from adjacent lines in the signature. Lasers designed according to this list will have an undisturbed tuning profile for one or more lines.

Schiffner, G.↗
NASA NTRS1971

CO2 laser experiments using nuclear reactions as the ionization source.

Experimental studies show that the output of a CO2 laser is significantly increased by products of the nuclear reaction He-3 (n,p)T. Helium-3 was used in lieu of the natural helium normally present in the 1:1:8 CO2:N2:He laser gas mixture (pressure = 6 torr). The laser assembly was then exposed to a reactor thermal neutron flux of about 100 million neutrons/sq cm/sec. Power output of the laser doubled while the electrical power input decreased; electrical efficiency was thus more than doubled. Results indicate that additional ionization by the energetic charged particles may be responsible for the improved laser performance.

Rhoads, H. S.↗
NASA NTRS1972

Mariner 6 and 7 ultraviolet spectrometer experiment - Implications of CO2/+/, CO, and O airglow.

The Mariner 6 and 7 UV spectrometer experiments observed intense emissions from CO, O, and CO2(+) in the Martian airglow. Analysis shows that they are excited predominantly by the absorption of solar EUV photons by CO2 and constitute a major energy-loss mechanism for the thermosphere. Models of the thermospheric temperature profile and the airglow layer that demonstrate the effects of neutral chemistry and ionospheric composition are developed. With their aid, the observed CO Cameron-band emission scale height of 19 (plus or minus 4.5) km is shown to suggest an exospheric temperature of 315 (plus or minus 75) K. Consideration of other data suggests a 'best' value of about 350 K. Within the uncertainties in the excitation efficiencies and in the thermospheric cooling mechanisms, the observations are consistent with the measured electron density. There is no indication in the data that the ionosphere is modified by the solar wind below 200 km.

Stewart, A. I.↗
NASA NTRS1972

Energy curves of CO2/-/.

Ab initio energy curves of the A super 2 sub 1 and B super 2 sub 1 states of CO2(-) have been obtained as a function of the bending angle. An analysis shows that gaseous CO2(-) in its ground vibrational level can have a relatively long life since the ion energy in the neighborhood of the ion equilibrium geometry is about 1 eV below the neutral molecule energy for that geometry.

Krauss, M.↗
NASA NTRS1972

Vibrational relaxation of the bending mode of shock-heated CO2 by laser-absorption measurements.

Study of the vibrational relaxation characteristics of shock-heated CO2 using a tuned CO2 laser absorption technique. Absorption-coefficient histories were obtained for a single rotational state in each of the -10 0- and -02 0- levels over the temperature range from 500 to 2000 K, and for 21 rotational states of the -10 0- level at 1000 K. These histories have been combined with translational-rotational temperature histories based on interferometer measurements to calculate vibrational relaxation times for the bending mode. The results verify the mutual equilibrium of the bending and symmetric-stretch modes due to Fermi resonance. The bending mode relaxation times are approximately 10% shorter than predicted from interferometer results using the ratio of specific heats. Furthermore, relaxation times based on measurements of different rotational states at 1000 K show a variation with quantum number J, indicating a possible rotational nonequilibrium during the vibration relaxation process.

Eckstrom, D. J.↗
NASA NTRS1972

Bosch CO2 reduction unit research and development.

Development of Bosch CO2 reduction units for manned spacecraft application has been in progress for a decade. The Bosch process catalytically reacts CO2 with H2 to produce water and carbon. The water may then be electrolyzed to close the biological oxygen and process hydrogen loops. A critical problem has been to confine the reaction so that carbon does not block flow and stop the process. Reaction isolation within a replaceable catalyst cartridge has been successfully demonstrated. Objectives of the current development program are a 25% reduction in operating power, an 80% reduction in expendable weight, and minimized resupply volume.

Holmes, R. F.↗
NASA NTRS1972

A curve-fitting technique for the determination of gain and saturation intensity in homogeneously-broadened gas lasers: Application to a waveguide CO2 laser

A least squares curve-fitting algorithm is derived which allows the simultaneous estimation of the small signal gain and the saturation intensity from an arbitrary number of data points relating power output to the incidence angle of an internal coupling plate. The method is used to study the dependence of the two parameters on tube pressure and discharge current in a waveguide CO2 laser having a 2 mm diameter capillary. It is found that, at pressures greater than 28 torr, rising CO2 temperature degrades the small signal gain at current levels as low as three milliamperes.

Degnan, J. J.↗
NASA NTRS1973

Absolute intensity and polarization of rotational Raman scattering from N2, O2, and CO2

An experimental examination of the absolute intensity, polarization, and relative line intensities of rotational Raman scattering (RRS) from N2, O2, and CO2 is reported. The absolute scattering intensity for N2 is characterized by its differential cross section for backscattering of incident light at 647.1 nm, which is calculated from basic measured values. The ratio of the corresponding cross section for O2 to that for N2 is 2.50 plus or minus 5 percent. The intensity recent for N2, O2, and CO2 are shown to compare favorably to values calculated from recent measurements of the depolarization of Rayleigh scattering plus RRS. Measured depolarizations of various RRS lines agree to within a few percent with the theoretical value of 3/4. Detailed error analyses are presented for intensity and depolarization measurements. Finally, extensive RRS spectra at nominal gas temperatures of 23 C, 75 C, and 125 C are presented and shown to compare favorably to theoretical predictions.

Penney, C. M.↗
NASA NTRS1973

Study of CO2 sorbents for extravehicular activity

Portable life support equipment was studied for meeting the requirements of extravehicular activities. Previous studies indicate that the most promising method for performing the CO2 removal function removal function were metallic oxides and/or metallic hydroxides. Mgo, Ag2, and Zno metallic oxides and Mg(OH)2 and Zn(OH)2 metallic hydroxides were studied, by measuring sorption and regeneration properties of each material. The hydroxides of Mg and Zn were not regenerable and the zinc oxide compounds showed no stable form. A silver oxide formulation was developed which rapidly absorbs approximately 95% of its 0.19 Kg CO2 Kg oxide and has shown no sorption or structural degeneration through 22 regenerations. It is recommended that the basic formula be further developed and tested in large-scale beds under simulated conditions.

Colombo, G. V.↗
NASA NTRS1973

Effects of contaminants in CO2 lasers.

A theoretical model which includes the effects of contaminants is developed for the high flow electric discharge CO2-N2-He laser. The model couples the excitation and relaxation processes, CO2 dissociation, and negative ion formation with the flow processes. An analysis of the effects of CO, O2, NO, and N2O impurities on the average small signal gain is presented. CO decreases the gain by collisional depopulation of the upper laser level, and O2, NO, and N2O reduce the gain by decreasing the electron density by forming stable negative ions. In particular, N2O exhibits a strong quenching effect because of its large dissociation cross section for the formation of O(-).

Smith, N. S.↗
NASA NTRS1973

Kinetics of CO2 production on Venus.

Consideration of theoretical limits and experimental data for the kinetics of the reaction quartz plus calcite yields wollastonite plus CO2 supports the concept of a short-term quasi-equilibrium state for the atmosphere of Venus. These data indicate that the time scale of this reaction and of any competing CO2 producing reaction may be as short as several hundred years or less at the inferred Venus surface temperatures.

Mueller, R. F.↗
NASA NTRS1973

Fabrication of a glycerol from CO2 reaction system, supplement

The fabrication, installation, and testing of a glycerol hydrogenation and a CO2 hydrogenation - CH4 partial oxidation units are reported. The glycerol system proved to be operational while the CO2 system was installed but not bought on operational steam.

Weiss, A. H.↗
NASA NTRS1974

Tables and charts of equilibrium normal shock and shock tube solutions for pure CO2 with velocities to 16 km/second

Equilibrium thermodynamic and flow properties are presented in tabulated and graphical form for moving, standing, and reflected normal shock waves in pure CO2, representative of Mars and Venus atmospheres. Properties include pressure, temperature, density, enthalpy, speed of sound, entropy, molecular weight ratio, isentropic exponent, velocity and species mole fractions. Incident (moving) shock velocities are varied from 1 to 16 km/sec for a range of initial pressure of 5 Newtons per square meter to 500 kilo Newtons per square meter. The present results are applicable to shock tube flows, and to free-flight conditions for a blunt body at high velocities. Working charts illustrating idealized shock-tube performance with CO2 test gas and heated helium and hydrogen driver gases are also presented.

Miller, C. G., III↗