Experimental study of the ignited mode in cesium thermionic converters

A variable spacing cesium thermionic converter of planar geometry has been tested under different conditions of emitter temperature, cesium pressure, and interelectrode spacing. It has been found that at low emitter temperatures of the order of 1,300 C to 1,400 C (degrees centigrade), high-power densities in the range of 2 to 4 watts/cm2 (watts per square centimeter) can be obtained with a molybdenum emitter. The performance under these conditions corresponds to an ignited mode where ions are introduced by a different mechanism than surface ionization.1