Chemical-thermionic auxiliary power systems

An analysis of the problems of matching the performance of a high-temperature plasma-thermionic static-energy conversion device to a heat source consisting of the combustion products of chemical fuels is presented. The thermodynamic relationships governing the efficiency and power densities of the thermionic converter as a function of cathode temperature and work function are established and the limitations imposed by positive ion space charge neutralization are pointed out. The temperature and heat flux limits set by the heat source are compared to the converter requirements and various matching problems are discussed.