operated in the conventional manner and therefore require an inverter to provide standard 110 v 60 hz ac electric power a model of the dependence of thermionic current on the gap between the microcathode and the underlying anode is provided this variation in current provides the physical basis for this invention which allows the thermionic converter to produce an ac power output directly that enables integration of thermionic converters into the power grid one embodiment the current invention integrates an actuator into the suspension of the microcathode so that its position can be modulated at the desired ac frequency e g 60 hz which will therefore modulate the current voltage characteristic from the thermionic converter with time closed loop control of the position of the micro cathode can be implemented with an integrated capacitive mems position sensor based on a high frequency electric readout with the proper choice for the gap as a function of time the resulting current voltage characteristic drives a purely resistive load ensuring optimal power transfer in one embodiment the current waveform current vs time function could preferably be sinusoidal with a dc offset by outputting power in this form minimal additional electrical components are needed to remove the dc offset and achieve synchronous ac with the power grid turning now to a more detailed example previously demonstrated tecs could only produce dc electricity necessitating an inverter for grid integration the invention provides microfabricated tecs to produce standard 60 hz ac electricity directly where the i v characteristic of a tec strongly depend on the distance between the cathode and anode by modulating the.