Thermoelectric Properties of the Plasma Diode

Lewis, H. W.; Reitz, John R.

doi:10.1063/1.1735351

Cited by 22 publications

(2 citation statements)

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“…This value of plasma resistivity is a calculated value for a cesium plasma at a pressure of \ mm Hg and a temperature of 2100°K taken from Ref. 4. The addition of the plasma resistance increases the minimum specific radiator area by 40% for a cathode temperature of 1700°K and 60% for a cathode temperature of 2300°K.…”

Section: Resultsmentioning

confidence: 92%

“…An emissivity of 0.9 was used, the same as for the thermionic system. For higher temperatures the radiator area is scaled inversely proportional to T ti 4 . For lower temperatures the radiator area is not increased because it is reasonable to expect that a turbine inlet temperature of 2000°F can be attained by the time a competitive thermionic system is developed.…”

Section: Comparison With Turbogeneratormentioning

confidence: 99%

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Thermionic Converters in a Large Nuclear Electric Powerplant in Space

Bernatowicz

1962

ARS Journal

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A parametric analysis of thermionic converter systems for large space powerplants is presented, and the thermionic systems are compared to the Rankine cycle turbogenerator on the basis of radiator area per unit of output power. Thermionic performance is computed with the height of the potential barrier above the Fermi levels in the cathode and anode as parameters. The minimum possible radiator area is determined for several configurations as a function of cathode and radiator temperatures. In comparing the thermionic and turbogenerator systems, it is assumed that radiator area is a good index of the powerplant mass and that corrosion limits the liquid metal temperature and this limit is the same in both systems. If the liquid metal is used to heat the cathodes, the thermionic system will be restricted to peak temperatures the same as those for a turbogenerator, and the thermionic system will require a larger radiator. Incorporating the thermionic diodes into a reactor fuel element and using a liquid metal to cool the anodes allows them to operate at a higher peak temperature for the same corrosion limit. This scheme permits substantial savings in radiator area, up to 50% at a cathode temperature of 1700°K and up to 80% at 2300°K.T HIS paper is concerned with the potential performance of thermionic converters used to generate megawatts of power in a nuclear electric powerplant in a space vehicle. Optimum theoretical performance will be computed, and a comparison with the performance of a turbogenerator will be made on the basis of some simplifying ground rules to identify those areas where the thermionic system can provide substantial gains and those where it cannot.The best criterion for evaluating a space powerplant is its mass, but computation of the mass requires a very detailed analysis. An easily computed index of performance which strongly reflects the mass of the system would be a useful criterion. In previous analyses (1-3), 2 the emphasis has been on efficiency. Results based on efficiency are important *in evaluating ground based powerplants or solar powerplants for space. However, for large nuclear electric powerplants for space vehicles, efficiency is not the best criterion. For such a system the radiator will be the largest component, except perhaps for the shield. The shield mass will not be affected much by the performance of the power conversion system, whereas the radiator size will be. In such a system, efficiency will be sacrificed in favor of a smaller radiator by raising the radiator temperature. In this paper the required radiator area per unit of output power, or specific radiator area, will be used as the criterion of merit. Diode Performance EquationsIn this analysis diode performance is computed with anode emission, heating due to electron kinetic energy, thermal radiation losses, and heat conduction and resistance losses in the series connector between adjacent diodes included. Also a range of internal resistance is included to incorporate the effects of electrode resistance and plasma ...

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Section: Resultsmentioning

confidence: 92%

Section: Comparison With Turbogeneratormentioning

confidence: 99%