Scaled experimental studies on radio frequency source for megawatt-class ionospheric heaters

Results of a scaled experiment using the electron beam produced by a gridded thermionic cathode from an Inductive Output Tube electron gun to drive an external lumped element circuit for high efficiency radio frequency generation are reported. The IOT gun produces an electron beam bunched at the driving frequency that is then collected by an external circuit for resonant impedance matching to the load. Results showed that effects such as the internal resistance of the inductor and deflection of beam electrons by the induced RF voltages on the beam collector are important considerations to be included in the design of a practical device using this configuration for high efficiency, MW-class RF sources for Mobile Ionospheric Heaters (MIHs).