Lewis Research Center

The fuel cell in space yesterday, today and tomorrow by Marvin Warshay ( )
2 editions published in 1989 in English and held by 306 WorldCat member libraries worldwide

Application of a hybrid generation/utility assessment heuristic to a class of scheduling problems by Ann O Heyward ( )
2 editions published in 1989 in English and held by 306 WorldCat member libraries worldwide

Channelized coplanar waveguide pin-diode switches by George E Ponchak ( )
2 editions published in 1989 in English and held by 304 WorldCat member libraries worldwide

Propfan Test Assessment (PTA) flight test report ( Book )
2 editions published in 1989 in English and held by 293 WorldCat member libraries worldwide

Tribological properties of polymer films and solid bodies in a vacuum environment by Robert L Fusaro ( )
2 editions published in 1987 in English and held by 270 WorldCat member libraries worldwide

Sensors for ceramic components in advanced propulsion systems summary of literature survey and concept analysis, task 3 report by W. H Bennethum ( )
3 editions published in 1988 in English and held by 267 WorldCat member libraries worldwide

A survey of oscillating flow in Stirling engine heat exchangers by T. W Simon ( )
2 editions published in 1988 in English and held by 265 WorldCat member libraries worldwide

Advanced electric propulsion and space plasma contactor research annual report by Paul J Wilbur ( )
4 editions published in 1987 in English and held by 264 WorldCat member libraries worldwide
"A series of experiments performed on an 8 cm dia. ring cusp magnetic field ion thruster are described. The results show the effects of anode and cathode position and size, ring cusp axial location and discharge chamber length on plasma ion energy cost and extracted ion fraction. Thruster performance is shown to be improved substantially when optimum values of these parameters are used. Investigations into the basic plasma phenomena associated with the process of plasma contacting are described. A theoretical model of discharge chamber operation developed for inert gas thrusters is extended so it can be used to evaluate the performance of mercury ion thrusters. Predictions of the model are compared to experimental results obtained on two 30 cm dia. thrusters. ... A theory of the plasma contacting process is described and experimental results obtained using three different hollow cathode-based plasma contactors are presented. The existence of a sheath across which the bulk of the voltage drop associated with the contacting process occurs is demonstrated. Test results are shown to agree with a model of a spherical, space-charge-limited double sheath. These results suggest that high pressure hollow cathode operation is difficult to achieve and that special care must be taken to assure that the electron emission region remains diffuse and attached to the low work function insert. ... A theoretical study of hollow cathode operation at high electron emission currents is presented. Preliminary experiments using the constrained sheath optics concept to achieve ion extraction under conditions of high beam current density, low net accelerating voltage and well columniated beamlet formation are discussed."

Oxygen diffusion and reaction kinetics in continuous fiber ceramic matrix composites by Michael C Halbig ( )
3 editions published in 1999 in English and held by 264 WorldCat member libraries worldwide
Previous stressed oxidation tests of C/SiC composites at elevated temperatures (350 deg C to 1500 deg C) and sustained stresses (69 MPa and 172 MPa) have led to the development of a finite difference cracked matrix model. The times to failure in the samples suggest oxidation occurred in two kinetic regimes defined by the rate controlling mechanisms (i.e.; diffusion controlled and reaction controlled kinetics). Microstructural analysis revealed preferential oxidation along as-fabricated, matrix microcracks and also suggested two regimes of oxidation kinetics dependent on the oxidation temperature. Based on experimental results, observation, and theory, a finite difference model was developed. The model simulates the diffusion of oxygen into a matrix crack bridged by carbon fibers. The model facilitates the study of the relative importance of temperature, the reaction rate constant, and the diffusion coefficient on the overall oxidation kinetics

Stress rupture behavior of silicon carbide coated, low modulus carbon/carbon composites by Gary A Rozak ( )
3 editions published in 1988 in English and held by 263 WorldCat member libraries worldwide