High Efficiency Thermionics (HET-IV) and Converter Advancement (CAP) programs. Final reports

Geller, C. B.; Murray, Christopher S.; Riley, David R.; Desplat, J.‐L.; Hansen, L. K.; Hatch, G. L.; McVey, J. B.; Rasor, N. S.

doi:10.2172/225989

Cited by 5 publications

(1 citation statement)

References 2 publications

(3 reference statements)

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“…θ = 1, thermionic properties of Cs-W surface resemble properties of pure cesium. For higher coverages, reference [33] addresses the hypothetical situation of the second layer of cesium adatoms reinforcing or diminishing the dipoles of the first layer. In either case, there was the negligible impact of the surface temperature on the Cs-W work function.…”

Section: Experimental Validationmentioning

confidence: 99%

Cesium seeding for effective electron transpiration cooling in hypersonic flows

Sahu

Tropina

Andrienko

et al. 2022

Plasma Sources Sci. Technol.

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The concept of electron transpiration cooling (ETC) uses thermionic emission of electrons from a low work function material to cool surfaces in hypersonic ﬂight. A theoretical estimate of the emission current is given by the Richardson-Dushman equation. In hypersonic ﬂights, the emission current can deviate from this estimate as the ambient air is partially ionized and a plasma sheath forms near the surface. Depending on the sheath structure, the emission current can be enhanced by the Schottky eﬀect, or could be reduced by the space charge eﬀects. In this study, we present a theoretical analysis of electron transpiration cooling of the leading-edge surface of a hypersonic vehicle, considering the transpiration of liquid cesium through a porous tungsten material. A part of the transpired cesium is adsorbed on the surface, which lowers the emitter work function, while the rest is evaporated due to high surface temperatures. Both the eﬀects provide substantial cooling. The evaporated cesium is ionized in the ambient air, which alters the plasma conductivity and reduces space charge eﬀects. The eﬀect of individual ﬁelds of ionized species near the surface is found to be negligible. Cesium transpiration is found to eliminate the requirement for an applied surface bias and enable stable operation at surface temperatures below 2000 K.

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Section: Experimental Validationmentioning

confidence: 99%

Cesium seeding for effective electron transpiration cooling in hypersonic flows

Sahu

Tropina

Andrienko

et al. 2022

Plasma Sources Sci. Technol.

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Thermionic Conversion

El‐Genk¹,

Paramonov²

1999

Wiley Encyclopedia of Electrical and Electronics Engineering

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The sections in this article are Background Work Function Modes of Operation Conversion Efficiency Types of Thermionic Converters Engineering Aspects of Thermionic Conversion Application to Space Electric Power Generation Application to Terrestrial Space Electric Power Generation

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Effect of oxygen on the operation of a single-cell thermionic fuel element

Paramonov¹,

El‐Genk²

1998

Journal of Nuclear Materials

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High Efficiency Thermionics (HET-IV) and Converter Advancement (CAP) programs. Final reports

Cited by 5 publications

References 2 publications

Cesium seeding for effective electron transpiration cooling in hypersonic flows

Cesium seeding for effective electron transpiration cooling in hypersonic flows

Thermionic Conversion

Effect of oxygen on the operation of a single-cell thermionic fuel element

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