Low-temperature thermionic emitter Interim scientific report, 9 Feb. 1968 - 8 Feb. 1969
Performance tests on alkaline earth oxide electron emitters at low temperatures
Dore, B. V.↗
SEARCH · Search NASA
Results for “thermionic”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Applied thermionic research Final report, 1 Dec. 1967 - 1 Dec. 1968
Quadrupole mass spectrometer for thermochemical properties of cesium oxide
Gyftopoulos, E. P.↗
Thermionic cathode evaluation study Interim report, 1 Apr. - 30 Jun. 1969
Life capabilities of pore dispenser, coated particle, and standard oxide cathodes at high temperature
Hill, F. T.↗
Oxygen effects in tantalum thermionic emitters.
Saturation electron emission characteristics from incompletely outgassed Ta wire emitters immersed in Cs vapor using plasma anode technique, noting oxygen effects
De Steese, J. G.↗
Load cell for thermionic converter tests
Stable, low duty cycle transistorized emitter follower load cell controls and absorbs large currents at low voltages. The use of energy storage in capacitors reduces auxiliary power source requirements. Low duty cycle pulse mode of operation reduces the average power handling requirement of all components.
Breitwieser, R.↗
Thermionic spacecraft design study Phase 1 report, 4 Feb. 1969 - 4 Jan. 1970
Design of nuclear electric propelled unmanned spacecraft
Source record↗
Some investigations of refractory metal systems of thermionic interest
Investigating interdiffusion of W-Ta, W-Mo, and W-Nb systems in refractory temperature range
Horner, M. H.↗
Design study of a high fuel fraction, externally-fueled thermionic diode suitable for in-pile testing
Engineering design of high fuel fraction diode for in-pile testing and evaluation of components under typical thermal stress conditions
Ernst, D. M.↗
Radioisotope thermionic power supply for spacecraft
Power supply design for unmanned electric propulsion missions to outer planets utilizes a store of curium-244 in compact array of capsules as energy source. Supply subassemblies are: heat source, converter equipment which supplies power, and safety equipment. System is designed for a 72,000 hour mission.
Homeyer, W. G.↗
Performances of the better metallic electrodes in cesium thermionic converters
Outputs are presented for some cesium diodes having primarily emitters of highly oriented polycrystalline or single-crystal 110 tungsten or .0001 rhenium. Power densities at 10 A/sq cm or 0.5 V appear as functions of emitter temperatures and electrode spacings.
Morris, J. F.↗
Cesium-diode performances from the 1963-to-1971 Thermionic Conversion Specialist Conferences
Indexes and summaries of the conference papers containing cesium-diode results are presented. Lists of converter materials, geometries, conditions, outputs, and lifetimes accompany the references. Simple chemical designations for emitters, collectors, and additives direct the reader to appropriate selections.
Morris, J. F.↗
Studies of thermionic materials for space power applications
The effect of microstructures of tungsten cladding on the transport rates of carbide fuel components was studied at 2073 K. hyperstoichiometric 90UC-10ZrC containing 4 wt% tungsten was clad with six types of tungsten material of 40 mil thickness. Screening tests of 1000 hours were carried out, and then selected samples were subjected to long-term tests up to 10,000 hours. The results indicate that the microstructures strongly affect the transport rates of carbide fuel components. The conditions for preparing (110) oriented cylindrical chloride tungsten emitters of high vacuum work functions were also investigated. Specimen sets were deposited on fluoride tungsten substrates for evaluating the effects of various deposition parameters on the degree and uniformity of the (110) preferred orientation and the vacuum work function. Long-term tests showed that the high vacuum work function of a cylindrical emitter was stable and the chloride tungsten to fluoride tungsten bond remained in excellent shape after 4850 hours at 2073 K.
Source record↗
Empirical formulation of thermionic converter electrode performance.
A simple empirical equation giving the electron emission current density in terms of the cesium arrival rate and the electrode surface temperature is presented. Oxygen effects are discussed. Applications of the equation are reported.
Smith, J. R.↗
A comparison of closed loop thermionic reactor control schemes.
The dynamics of the constant-voltage and constant-emitter-temperature control schemes are described. The closed loop responses to load changes, converter failures and reactivity perturbations are shown. Both control schemes inherently allow load voltages to vary during transients. An alternative control scheme is proposed which allows constant load voltage while preserving constant emitter temperatures.
Sawyer, C. D.↗
Reactor core length, externally configured thermionic converter.
Results of testing a converter having an external emitter configuration for 190 hours using RF induction heating. The converter was assembled with a rhenium emitter, 25.4 cm long, having a 91.2 sq cm emitting area, and a niobium collector with a molybdenum coating to improve its electronic property. The collector was water-cooled. The test included: static power output measurements, dynamic characteristics, and the effects of the temperature distribution along the emitter. The maximum power output achieved from the converter at an emitter temperature of 1942 K was 178 W at 0.48 V output, with a power density of 1.95 W/sq cm and an efficiency of 5.5%. The static characteristics also indicated that, with a constant power input, the converter power output does not vary with the output voltage as a result of self-adjustment of the emitter temperature. An investigation of the effects of the temperature distribution along the emitter length showed a 33% improvement in the converter output power with a flattening of the emitter temperature.
Shimada, K.↗
Probe measurements of a cesium plasma in a simulated thermionic energy converter.
Explore the source record for details and available documents.
Shimada, K.↗
A new method for the measurement of electron drift velocity based upon a study of electrical conduction in gas filled, cylindrical, thermionic diodes
Explore the source record for details and available documents.
Meisel, L.↗
Surface properties of thermionic electrodes
A quasi-equilibrium model which provides semiquantitative predictions of the oxygen reaction with refractory metals was developed at high temperature and low pressure. Extensive experimental data was obtained on adsorption and work function properties for a wide variety of adsorbates (Cs, K, Na, I, Br, Cl, and O) on several refractory metals (W, Ta, Mo, and Re). Conclusions and recommendations for research on alkali metal adsorption, oxygen adsorption, and adsorption of cesium - oxygen mixtures are included.
Stickney, R. E.↗