Predicting cathode life expectancy and emission quality from PWFD measurements

Cattelino, M.; Miram, G.

doi:10.1016/s0169-4332(96)00718-0

Cited by 40 publications

(15 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Going up in temperature usually did not take as long to reach the steady state emission. Figures 1a and 1b show the data obtained from the 311XM cathode, plotted in the forms of Miram (cathode loading) curves and the practical work function distribution (PWFD) curves [2]. In this case, the cathode had been activated at 1025C b and the pressure was 1.2 x 10 -8 Torr.…”

Section: Test Resultsmentioning

confidence: 99%

Gas poisoning of 612-M and 311-XM cathodes

Kwan

Bieniosek

Henestroza

et al. 2008

2008 IEEE International Vacuum Electronics Conference

View full text Add to dashboard Cite

show abstract

Section: Test Resultsmentioning

confidence: 99%

Gas poisoning of 612-M and 311-XM cathodes

Kwan

Bieniosek

Henestroza

et al. 2008

2008 IEEE International Vacuum Electronics Conference

View full text Add to dashboard Cite

show abstract

“…The efficiency of thermionic emission is directly related to this work function, as well as other surface properties (Herring 1949). The data of Figure 10 provide some guidelines for target material systems where practical low work function values are achievable (Cattelino 1997). …”

Section: Commercial Dispenser Cathode Propertiesmentioning

confidence: 92%

“…An example is the macro-scale dispenser cathode that uses a metal/ barium oxide matrix with a metal capping layer capable of producing a low work function at the surface. Cortenraad (1999) has shown that an O-Ba dipole chain is most likely responsible for surface work function lowering. Calculation by Müller (1997) and measurements by show that a minimum work function of 1.4 eV is possible for a O-Ba complex on tungsten.…”

Section: Mtc Descriptionmentioning

confidence: 99%

See 1 more Smart Citation

Low work function material development for the microminiature thermionic converter.

Zavadil¹,

Battaile²,

Marshall³

et al. 2004

View full text Add to dashboard Cite

Thermionic energy conversion in a miniature format shows potential as a viable, high efficiency, micro to macro-scale power source. A microminiature thermionic converter (MTC) with inter-electrode spacings on the order of microns has been prototyped and evaluated at Sandia. The remaining enabling technology is the development of low work function materials and processes that can be integrated into these converters to increase power production at modest temperatures (800 -1300 K). The electrode materials are not well understood and the electrode thermionic properties are highly sensitive to manufacturing processes. Advanced theoretical, modeling, and fabrication capabilities are required to achieve optimum performance for MTC diodes. This report describes the modeling and fabrication efforts performed to develop micro dispenser cathodes for use in the MTC. Figure 24. A time progression from a simulation of microstructure coarsening in a layered twophase material. The simulation grid has 100x100x100 points, the interfacial energy between the two phases is one, the time increment is ∆t = 1, and the temperature is T = 2. The images, starting from top left and progressing to the right, are from simulation times of 0, 2000, 4000, 6000, 8000, 10000, 12000, 14000, 16000, 18000, 20000, 22000, 24000, 26000, 28000, 30000, 40000, 100000, 200000, and 300000. 37 Figure 25. Examples of site exchange paths in a two-dimensional system containing a strip of one phase embedded in a matrix of another. The energy change involved in reaching each configuration is written in white text at the lower right of each frame. 38 Figure 26. A time progression from a simulation of microstructure coarsening in a layered twophase material with a diffusing surfactant. The simulation grid has 200x200x200 points, the interfacial energy between the two phases is one, the time increment is ∆t = 0.5, and the temperature is T = 3. The images, starting from top left and progressing to the right, are from simulation times of 0, 100, 200, 400, 600, 1000, 1400, 1800, 2200, 2400, 2600, 2800, 3000, 3300, 3600, 3900, 4200, and 4500. 39 Figure 27. Evolution of surfactant concentration from a midplane source. The simulation grid has 200x200x200 points and the time increment between diffusion steps is 0.5. The images, starting from top left and progressing to the right, are from simulation times of 0, 100, 200, 400, 600, 1000, 1400, 1800, 2200, 2400, 2600, 2800, 3000, 3300, 3600, 3900, 4200, and 4500. 40 Figure 28. A time progression from a simulation of simultaneous microstructure coarsening and chemical reaction in a layered two-phase material. The simulation grid has 96x96x96 points, the time increment is t = 0.5, and the temperature is T = 3. The images, starting from top left and progressing to the right, are from simulation times of 0, 100, 200, 300, 400, 500, 600, and 700. In the nomenclature of Tables 1 and 2, the blue sites are species A, the red are B, and the green are C. The interfacial energies are E AB = 1, E AC = 0.8, E AO = 1, E BC = 0....

show abstract

“…One is the Miram curve and practical work function distribution (PWFD) plot [14] and the other is based on Longo-Vaughan's (L-V) relationship [15]. The first method includes only the Richardson-Dushman equation to model the thermionic emission and the second method also takes into account the Schottky effect and space charges.…”

Section: Emission Mechanismmentioning

confidence: 99%

High current density Sc2O3-W matrix dispenser cathode

Wang

Zhang

Liu

et al. 2011

Sci. China Inf. Sci.

View full text Add to dashboard Cite

Sc 2 O 3 -W matrix dispenser cathodes have been prepared by powder metallurgy method and tested in Pierce electron guns. The emission current density can reach 72 A/cm 2 at 900 • C and over 100 A/cm 2 can be achieved at a temperature higher than 950 • C. The emission improves and then keeps stable with time throughout the life testing period of 330 h at a continuous loading of 88 A/cm 2 pulsed current density with a pulse width of 10 μs and duty cycle of 0.2%. The cathode surface is covered by a semiconductor multilayer composed of Ba, Sc and O. The emission behavior of the cathode can be explained by a semiconductor model. CitationWang J S, Zhang X Z, Liu W, et al. High current density Sc2O3-W matrix dispenser cathode. Sci China Inf Sci, 2012, 55: 98-105,

show abstract

Predicting cathode life expectancy and emission quality from PWFD measurements

Cited by 40 publications

References 0 publications

Gas poisoning of 612-M and 311-XM cathodes

Gas poisoning of 612-M and 311-XM cathodes

Low work function material development for the microminiature thermionic converter.

High current density Sc2O3-W matrix dispenser cathode

Contact Info

Product

Resources

About