Results from the microminiature thermionic converter demonstration testing program

King, Donald B.; Zavadil, Kevin R.; Ruffner, Judith A.

doi:10.1109/iecec.2000.870697

Cited by 5 publications

(1 citation statement)

References 2 publications

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“…3) Sc-in-oxides: A related approach implemented by Cui et al [123]- [125] prepares Sc 2 O 3 -doped pressed cathodes by fabricating Sc 2 O 3 and Ba-Ca-aluminate co-doped W powders using a spray drying method and a two-step hydrogen reduction process. In this "Ba scandate" or "scandiadoped powder (SDP)" fabrication approach, cathode pellets are pressed and sintered from a mixture of W powder and various Ba x Sc y O x+ 3 2 y powders [11], [126]. This approach does away with a traditional impregnation step by directly incorporating the impregnant precursor oxides in the pressed pellet.…”

Section: A Fabricationmentioning

confidence: 99%

A Review of Sc-containing "Scandate" Thermionic Cathodes

Seif¹,

Zhou²,

Liu³

et al. 2022

Preprint

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Although thermionic emission has been studied for more than 100 years, recent interest in novel electron devices for military and civilian use has led to a surge in demand for cathodes with enhanced emission properties (e.g. higher current density, more uniform emission, lower operating temperatures, or extended in-service longevity). Sc-containing "scandate" cathodes have been widely reported to exhibit superior emission properties compared to previous-generation thermionic cathodes, including oxide, B-, and M-type cathodes. Despite extensive study spanning several decades, the mechanism by which the addition of Sc enhances cathode emission remains ambiguous, and certain limitations -non-uniform emission, low reproducibility, inconsistent longevity -continue to prevent widespread commercial integration of scandate cathodes into electron devices. This review attempts to survey the literature to-date addressing the fabrication, structure, and properties of scandate cathodes, with particular attention to studies addressing the role of Sc in enhancing emission.

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Section: A Fabricationmentioning

confidence: 99%

A Review of Sc-containing "Scandate" Thermionic Cathodes

Seif¹,

Zhou²,

Liu³

et al. 2022

Preprint

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Microfabricated Thermally Isolated Low Work-Function Emitter

Lee

Bargatin

Vancil

et al. 2014

J. Microelectromech. Syst.

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In this paper, we report low work function mechanically and thermally robust microfabricated thermionic emitters. Conformal deposition of polycrystalline-silicon carbide (poly-SiC) was used to form stiff suspension legs with U-shaped cross sections, which increased the out-of-plane rigidity and helped to maintain a micrometer-scale gap between emitter and collector. The structurally robust poly-SiC suspended structure was coated with a thin tungsten layer to improve adhesion of a work function lowering coating (BaO/SrO/CaO). The measured emitter work function was 1.2 eV and emission current density was >0.1 A/cm 2 , which are promising for applications such as thermionic energy converters.[ 2013-0238]Index Terms-Thermionic emitter, thermionic cathode, energy conversion efficiency, barium coating, barium oxide coating, work function lowering, silicon carbide.

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Micro combustion-thermionic power generation: feasibility, design and initial results

Zhang

Najafi

Bernal

et al.

TRANSDUCERS '03. 12th International Conference on Solid-State Sensors, Actuators and Microsystems. Digest of Technical Papers (

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This paper reports for the first time the design, development and initial results from a micro power generator based on thermionic (TI) emission using combustion. Several major results are achieved. .Thinfilms of BaO are integrated with Si to form the emitter and collector of a TI converter. Field emission and TI emission currents are successfully measured from this converter. Thick S O 2 rings are formed to achieve excellent thermal isolation. An integrated process to fabricate micromachined TI power generators is developed. Combustion has been achieved in the micromachined combustor. And power generation of ' -1 pW has been measured in emitter-collector subsystem testing. Improvement of the device and testing is needed for achieving system-level power generation from combustion.

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Results from the microminiature thermionic converter demonstration testing program

Cited by 5 publications

References 2 publications

A Review of Sc-containing "Scandate" Thermionic Cathodes

A Review of Sc-containing "Scandate" Thermionic Cathodes

Microfabricated Thermally Isolated Low Work-Function Emitter

Micro combustion-thermionic power generation: feasibility, design and initial results

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