Thermionic Generation

The paper considers the basic electrical operation of thermionic generators from first principles. After reviewing the basic ideas of diode generation, the process of thermionic emission and the effects of contact potentials and biased contacts are discussed. An idealized model of the generator is set up neglecting the effects of space charges, and the various potential diagrams are developed using a critical point related to the contact potential, at which the generator characteristics show a sharp discontinuity. A graphical presentation of the output characteristics is developed on which load lines can be drawn to determine performance details. The affects of the space charge within the electrode gap and the various resistances within the device are considered as perturbations of the idealized model. Various ways of minimizing the deleterious effects of the space charge are discussed. These are the use of a small gap, combined electric and magnetic fields, and ion compensation using resonance ionization.