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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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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Elemental composition of aerosols in fourteen experiments of the Cloud Condensation Nuclei Workshop

Aeosols were collected with two Ci impactors and analyzed with proton induced X-ray emission (PIXE) for chemical composition and to detect if contamination was present. One of the impactors sampled the generated aerosols; the other impactor sampled droplets from a diffusion cloud chamber. The purpose of the experiments was to test the feasibility of a study of the transfer of chemical elements from the fine particle sizes to the coarse particle sizes, after CCN are activated and cloud droplets are formed. The data indicated that sulfur-containing aerosols did exhibit the expected transfer.

Mach, W. H.↗
NASA NTRS2011

A State-of-the-Art Experimental Laboratory for Cloud and Cloud-Aerosol Interaction Research

The state of the art for predicting climate changes due to increasing greenhouse gasses in the atmosphere with high accuracy is problematic. Confidence intervals on current long-term predictions (on the order of 100 years) are so large that the ability to make informed decisions with regard to optimum strategies for mitigating both the causes of climate change and its effects is in doubt. There is ample evidence in the literature that large sources of uncertainty in current climate models are various aerosol effects. One approach to furthering discovery as well as modeling, and verification and validation (V&V) for cloud-aerosol interactions is use of a large "cloud chamber" in a complimentary role to in-situ and remote sensing measurement approaches. Reproducing all of the complex interactions is not feasible, but it is suggested that the physics of certain key processes can be established in a laboratory setting so that relevant fluid-dynamic and cloud-aerosol phenomena can be experimentally simulated and studied in a controlled environment. This report presents a high-level argument for significantly improved laboratory capability, and is meant to serve as a starting point for stimulating discussion within the climate science and other interested communities.

Fremaux, Charles M.↗
NASA NTRS1992

Clouds of ammonia ice - Laboratory measurements of the single-scattering properties

A new apparatus for the growth of clouds of ammonia and water ice has been developed which represents an improvement over the one constructed by Holmes (1981). Better thermal control of the cloud chamber has been achieved so that colder temperature relevant to the outer planets' atmospheres could be reached. The angular resolution of the scattering measurements has been improved from 10 deg to about 2 deg. A rotating filter wheel combined with a much larger computer allows a complete data set to be collected in three colors once per second. This capability is important in monitoring cloud properties as they change with time and in collecting data on larger crystals which can fall through the beam in a few seconds.

Pope, Shelly K.↗
NASA NTRS1982

Development of cosmic ray techniques

It is pointed out that most advances of cosmic-ray physics have been directly related to the development of observational techniques. A review is presented of the history of the evolution of the techniques and equipment for the study of cosmic-ray physics, taking into account the new scientific advances accompanying each new development related to experimental technology. All of the early observations were performed by means of ionization chambers. These chambers had already been in use for a number of years, when they were first applied to the study of cosmic rays in the early years of this century. However, an application to the low-intensity cosmic radiation required special refinements. Attention is given to the design of suitable electrometers, the development of self-recording instruments, the 'tube counter', the development of the coincidence method, a cosmic-ray 'telescope', a magnetic lens for cosmic rays, an arrangement of Geiger-Mueller counters for the demonstration of secondary radiation, cloud chambers, scintillation counters, and air shower experiments.

Rossi, B.↗
NASA NTRS1971

Comparison of the energy response of an ionization spectrometer for pions and protons

An ionization spectrometer consisting of a sandwich of iron absorbers and plastic scintillation counters was used to measure the energy of pions and protons in the interval 10 to 1000 GeV. For the limited energy interval of 10 to 40 GeV, pions and protons were identified by an air cerenkov counter. Interactions in carbon were studied in a multiplate cloud chamber placed between the cerenkov counter and the spectrometer. Knowledge of these interactions were used in conjunction with a Monte Carlo simulation of the cascade process to study differences in the response of the spectrometer to pions and protons.

Jones, W. V.↗
NASA NTRS1972

Project Fog Drops. Part 2: Laboratory investigations

Measurements of the total nucleus concentration and cloud condensation nuclei (CCN) were acquired for several conditions representing both high normal and severe pollution levels for the Los Angeles Basin as well as clean filtered air. The data show that in filtered air there is a large photochemically induced increase in the total particle content within a few minutes after starting the lamp. The concentration of CCN remains near zero, until sufficient coagulation and condensation occurs on the smaller Aitken particles. The addition of gaseous pollutants to filtered air results in large increases in the photochemical production of both the cloud and Aitken nucleus concentration. Fogs were also generated under controlled, reproducible conditions in the cloud chamber and seeded with aerosols of various compounds which form monomolecular surface films at air-water interfaces. Visibility characteristics and droplet data were obtained. The data suggest that droplet growth on treated nuclei can be retarded but fog formation was not significantly altered by the chemical seeding.

Kocmond, W. C.↗
NASA NTRS1974

Optical holography applications for the zero-g Atmospheric Cloud Physics Laboratory

A complete description of holography is provided, both for the time-dependent case of moving scene holography and for the time-independent case of stationary holography. Further, a specific holographic arrangement for application to the detection of particle size distribution in an atmospheric simulation cloud chamber. In this chamber particle growth rate is investigated; therefore, the proposed holographic system must capture continuous particle motion in real time. Such a system is described.

Kurtz, R. L.↗
NASA NTRS1976

Heat transfer device

An improved heat transfer device particularly suited for use as an evaporator plate in a diffusion cloud chamber. The device is characterized by a pair of mutually spaced heat transfer plates, each being of a planar configuration, having a pair of opposed surfaces defining therebetween a heat pipe chamber. Within the heat pipe chamber, in contiguous relation with the pair of opposed surfaces, there is disposed a pair of heat pipe wicks supported in a mutually spaced relationship by a foraminous spacer of a planar configuration. A wick including a foraminous layer is contiguously related to the external surfaces of the heat transfer plates for uniformly wetting these surfaces.

Eaton, L. R.↗
NASA NTRS1978

Atmospheric Cloud Physics Laboratory thermal control

The paper presents the development background and the present status of the Atmospheric Cloud Physics Laboratory (ACPL) thermal control capability. The ACPL, a Spacelab payload, is currently in the initial flight hardware development phase for a first flight scheduled in June 1981. The ACPL is intended as a facility for conducting a wide variety of cloud microphysics experimentation under zero gravity conditions. The cloud chambers, which are key elements of the ACPL, have stringent thermal requirements. Thus the expansion chamber inner walls must be uniform to within + or - 0.1 C during both steady-state and transient operation over a temperature range of +30 to -25 C. Design progression of the expansion chamber, from early in-house NASA-MSFC concepts (including test results of a prototype chamber) to a thermal control concept currently under development, is discussed.

Moses, J. L.↗
NASA NTRS1978

Vertical profiles of condensation nuclei

Condensation nuclei measurements using a low supersaturation (about 10%) thermal gradient diffusion cloud chamber (TGDCC) and a high supersaturation (about 200%) expansion type instrument were compared on a series of three balloon flights over Laramie, Wyoming. In general, the two instruments produced similar vertical profiles but some discrepancies remain unexplained. Agreement between the two would indicate that the low supersaturations used in the TGDCC were still large enough to cause the instrument to count essentially all of the particles present. The TGDCC condensation nuclei (CN) counter was flown at several sites in both the Northern and Southern Hemispheres. The results indicate the existence of a relative maximum in the CN mixing ratio associated with the upper equatorial troposphere and what appears to be a worldwide constant mixing ratio of CN above 20-25 km.

Rosen, J. M.↗
NASA NTRS1978

Airborne measurements of cloud forming nuclei and aerosol particles at Kennedy Space Center, Florida

Results of airborne measurements of the sizes and concentrations of aerosol particles, ice nuclei, and cloud condensation nuclei that were taken at Kennedy Space Center, Florida, are presented along with a detailed description of the instrumentation and measuring capabilities of the University of Washington airborne measuring facility (Douglas B-23). Airborne measurements made at Ft. Collins, Colorado, and Little Rock, Arkansas, during the ferry of the B-23 are presented. The particle concentrations differed significantly between the clean air over Ft. Collins and the hazy air over Little Rock and Kennedy Space Center. The concentrations of cloud condensation nuclei over Kennedy Space Center were typical of polluted eastern seaboard air. Three different instruments were used to measure ice nuclei: one used filters to collect the particles, and the others used optical and acoustical methods to detect ice crystals grown in portable cloud chambers. A comparison of the ice nucleus counts, which are in good agreement, is presented.

Radke, L. F.↗
NASA NTRS1981

Description and discussion of the NRL TGDCC

The NRL thermal gradient diffusion cloud chamber (TGDCC) consists of two plates 7.5 cm in diameter separated by 1.25 cm and covered with saturated filter paper. The cylindrical wall separating the plates is glass. The top plate is at room temperature and the bottom plate is cooled with a thermoelectric cooler. The temperature difference is measured with several sets of thermocouples. The CCN concentration was determined from the video recording. This procedure of averaging the maximum count obtained on several successive recordings at the same supersaturation results in concentrations which are somewhat higher than concentrations calculated from an average across the plateau.

Hoppel, W. A.↗
NASA NTRS1981

Diffusion tube

The diffusion tube was designed to operate below about 0.25 percent of water supersaturation. It is simply a long tube lined on the inside with a damp chamois cloth, and heated isothermally to a few degrees centigrade above the incoming air. The diffusion coefficient for water vapor is slightly larger than that for heat, making it possible to supersaturate the airflow. This is the same principle by which transient supersaturations may occur in parallel plate cloud chambers. Only the diffusion of vapor and heat from the walls into the moving air are considered.

Leaitch, R.↗
NASA NTRS1983

Condensation nuclei events at 30 km and possible influences of solar cosmic rays

Two recent observations have provided the basis for study of a relationship between solar activity and the formation of small particles in the earth's atmosphere; the discovery of annual increases of condensation nuclei (CN) at 30 km and the detection of sulfuric acid molecules in large negative ion clusters in the 25-35-km altitude region. These observations have led to formulation and testing of a model wherein CN are formed in a 'polar cloud chamber' supersaturated with sulfuric acid vapor and triggered by ionization associated with solar flare cosmic radiation. It is concluded that such a model provides a potential explanation of the observations.

Hofmann, D. J.↗
NASA NTRS1983

Stratospheric condensation nuclei and possible solar influences

Balloon-borne measurements of condensation nuclei and H2SO4 molecules in large negative ion clusters have been made in the stratosphere at around 30 km altitude. The nuclei observed were in the 0.01-0.1 micron diameter range. Consideration was given to sunspot activity as a triggering event for ionization of upper atmospheric H2SO4 species and subsequent formation of the nuclei. A numerical model was defined for a steady state between the H2SO4 association and ion recombination in order to determine a critical nucleation rate. It is concluded that condensation nuclei are produced in ion nucleation in an H2SO4 supersaturated polar cloud chamber, with the process being initiated by solar flare particle ionization.

Hofmann, D. J.↗
NASA NTRS1985

Missing energies at pair creation

Wilson cloud chamber measurements of the separated spectra of positrons and electrons produced by gamma quanta of 6.14 MeV differ considerably from the theoretically predicted spectra by BETHE and HEITLER, but are in good agreement with those of a modified theory of pair creation.

El-Ela, A. A.↗