Energy conversion device and methods of making

Claim 1

A HEAT-TO-ELECTRICAL ENERGY CONVERTER COMPRISING AT LEAST FIRST AND SECOND STAGE DEVICES IN CASCADED ARRANGEMENT, SAID DEVICES BEING HERMETICALLY SEALED IN ENCLOSING MEANS AND EACH COMPRISING A CATHODE AND ANODE HAVING CLOSELY SPACED ACTIVE SURFACES WITH THE ACTIVE SURFACE OF SAID CATHODE BEING ADAPTED FOR ELECTRON EMISSION UPON HEATING, THE CATHODE OF THE FIRST STAGE DEVICE BEING AT A HEAT INPUT REGION OF SAID CONVERTER FOR BEING RENDERED EMISSIVE BY HEAT ENTERING SAID DEVICE AT SAID INPUT REGION, THE ANODE OF THE FIRST STAGE DEVICE CONSTITUTING A HEAT SINK AND BEING IN DIRECT HEAT-TRANSFERRING RELATION WITH THE CATHODE OF THE SECOND STAGE DEVICE, WHEREBY SAID CATHODE OF SAID SECOND STAGE DEVICE IS ADAPTED FOR BEING RENDERED EMISSIVE BY HEAT EMANATING FROM SAID ANODE OF SAID FIRST STAGE DEVICE, AND THE ACTIVE SURFACE OF THE CATHODE OF SAID SECOND STAGE DEVICE HAVING A LOWER WORK FUNCTION AND THEREBY ADAPTED FOR BEING RENDERED EMISSIVE AT A LOWER OPERATING TEMPERATURE THAN THAT OF SAID CATHODE OF SAID FIRST STAGE DEVICE.