Electronic Temperature-Flattening of Thermionic Reactors

A method for electronically temperature-flattening a "flashlight-type" thermionic reactor with both axial and radial heat generation nonuniformities is described. The method, which makes use of compensating electron cooling variation while satisfying the voltage- and current-matching constraints on the in-core series-parallel diode network, results in substantially uniform emitter temperatures throughout the reactor. Novel analytical techniques for temperature-flattening a nonuniform reactor are described and used to generate specific illustrative designs. It is shown that, even with severe nonuniformities, the temperature-flattened reactor exhibits almost as high a power density and conversion efficiency as a reactor using fuel-zoning for full power flattening. By eliminating the need for fuel-zoning, the concept described here reduces the critical size and system weight, and permits the use of thicker emitter walls for enhanced reliability