Investigations of electron emission characteristics of low work function surfaces Final report, 28 Sep. 1966 - 13 Nov. 1967
Electron emission characteristics of low work function surfaces
Bell, A. E.↗
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Single plane work function coverage relationships for cesium and oxygen coadsorbed on tungsten
Probe field emission studies of work function and energy distribution of cesium-oxygen-tungsten system
Source record↗
The work function determination and surface characterization of vapor deposited rhenium.
Vapor deposited rhenium surface characteristics and work functions obtained from 1800 to 2300 degrees K by X ray diffraction analysis
Campbell, A. E., Jr.↗
Performance of a cylindrical geometry thermionic converter with an improved work function tungsten emitter.
Cylindrical geometry thermionic converter with vapor deposited W emitter, noting power density performance characteristics, work function and long term stability
Holland, J. W.↗
Surface cleanliness research using the work function technique Final report
Argon ion bombardment and other surface cleaning methods evaluated on polycrystalline tungsten by work function techniques
Brock, F. J.↗
Work function measurements by the field emission retarding potential method
Using the field emission retarding potential method true work functions have been measured for the following monocrystalline substrates: W(110), W(111), W(100), Nb(100), Ni(100), Cu(100), Ir(110) and Ir(111). The electron elastic and inelastic reflection coefficients from several of these surfaces have also been examined near zero primary beam energy.
Swanson, L. W.↗
Question on the measurement of the metal work function in an electron spectrometer by the secondary-electron emission threshold method
The feasibility of measuring metal work functions using the secondary emission threshold method and an electron spectrometer is demonstrated. Measurements are reported for Nb, Mo, Ta, and W bombarded by Ar(+) ions.
Alov, N. V.↗
Electron theory of metals, bases on Fermi statistics. Part I - General data, flow processes, and work functions
Electron theory of metals based on Fermi statistics and Bose-Einstein statistics - general data, flow processes, and work functions
METAL↗
<theoretical studies on the relationship between the thermionic work function of re- fractory intermetallic compounds and their electronic and crystal structures< progress report letter, 1 jul. - 31 dec. 1964
Thermionic work function of refractory metallic compounds and electronic and crystal structure - emissivity measurement and diode fabrication
DIODE↗
Thermionic scanner pinpoints work function of emitter surfaces
In the electron tube testing, a thermionic scanner makes accurate spatial resolution measurements of the metallic surface work functions of emitters. The scanner determines the emitter function and its local departures from the mean value on a point-by-point basis for display on an oscilloscope.
Rasor, N. S.↗
Experimental measurements of the work functions and desorption energies of the systems O-W, O-Mo, O-Re, O-Ta, and Cs-O-Ta.
Thermionic work functions and desorption energies for oxygen on polycrystalline W, Mo and Re filaments, discussing oxygen pressure and filament temperature
Fehrs, D. L.↗
Work function measurements by the field emission retarding potential method.
Description of the theoretical foundation of the field electron retarding potential method, and review of its experimental application to the measurement of single crystal face work functions. The results obtained from several substrates are discussed. An interesting and useful fallout from the experimental approach described is the ability to accurately measure the elastic and inelastic reflection coefficient for impinging electrons to near zero-volt energy.
Strayer, R. W.↗
Work function measurement of lanthanum-boron compounds
The relationship between emission properties and sample composition is studied for lanthanum-boron compounds. Specifically, the La-B system is considered between 1400 and 2100 K and between LaB(4.24) and LaB(29.2) to determine the phase relationship, chemical activity of the compounds, vapor composition, and vaporization rate. The results indicate that: (1) a blue-colored phase near LaB(9) exists between a purple-colored LaB(6) and elemental boron, (2) vaporization is sufficiently more rapid than diffusion so that great compositional differences exist between the surface and the interior, (3) an activation energy lowers the boron vaporization rate from LaB(6), and (4) a steady-state surface composition between LaB(6.04) and LaB(6.07) exists for freely vaporizing materials as a function of interior composition, purity, and temperature. It is noted that the ultimate life of a thermionic diode is governed by electrode vaporization rate whereas efficiency is governed by the electrode work function.
Jacobson, D. L.↗
Low-work-function surfaces produced by cesium carbonate decomposition
Cesium carbonate (Cs2CO3) was heated to the decomposition temperature of approximately 600 C. The nonvolatile decomposition products were condensed on a nickel substrate while the carbon dioxide was removed by pumping. The deposited material is characterized by an effective work function of between 1.05 and 1.15 eV at 450 K and by photoemission in the visible and near-infrared region of the spectrum. It is suggested that the deposited material consists of Cs2O, possibly Cs2O2, and adsorbed cesium. Silver, evaporated from a heated silver bead, produced the typical photoemissive and thermionic properties of a silver-oxygen-cesium (S-1) photocathode. The material may be of interest for thermionic energy converters and for the formation of silver-oxygen-cesium photocathodes.
Briere, T. R.↗
Evidence for the negative work function associated with positrons in gold.
Observation that positrons which have been thermalized in various moderators and coated with approximately 200-A gold leave the gold surface with an energy which peaks between 0.75 and 2.90 eV. This energy is thought to be associated with a positron or 'negative' work function of gold.
Costello, D. G.↗
Work function determination of promising electrode materials for thermionic converters
Work performed on this contract was primarily for the evaluation of selected electrode materials for thermionic energy converters. The original objective was to characterize selected nickel based superalloys up to temperatures of 1400 K. It was found that an early selection, Inconel 800 produced a high vapor pressure which interfered with the vacuum emission measurements. The program then shifted to two other areas. The first area was to obtain emission from the superalloys in a cesiated atmosphere. The cesium plasma helps to suppress the vaporization interference. The second area involved characterization of the Lanthanum-Boron series as thermionic emitters. These final two areas resulted in three journal publications which are attached to this report.
Jacobson, D.↗
Work function determination of promising material for thermionic converters
The work done to fabricate Marchuk plasma discharge tubes for measurement of the cesiated emission of lanthanum hexaboride and thoriated tungsten electrodes is described. A photon counting pyrometer was completed and is to be calibrated with a gold standard.
Jacobs, M. H.↗
Passive Charge Dissipating Work Function Matching Coating for Reducing Adhesion of Lunar Dust
The NASA Glenn Research Center Environmental Effects and Coatings Branch is developing a passive coating for lunar dust mitigation. This simple, transparent, conductive coating will be capable of reducing lunar dust adhesion to surfaces and dissipating surface charge. Anticipated benefits include compatibility with active dust mitigation strategies, improved efficiency and performance of solar cells and thermal control surfaces, and protection of astronauts and equipment on the lunar surface.
Lunar dust↗