Various disclosed embodiments include thermionic energy converters and electronic circuitry for generating pulses for igniting plasma in a hermetic package of a thermionic energy converter. In various embodiments, an illustrative thermionic energy converter includes a hermetic package charged with a non-cesium gas additive. The hermetic package is configured to route into the hermetic package pulses for igniting plasma in the hermetic package. A cesium reservoir is disposed in the hermetic package. A cathode is disposed in the hermetic package and an anode is disposed in the hermetic package.