Modeling and design of high-power single-beam and multiple-beam Inductive Output Tubes

The Inductive Output Tube (IOT) is today the device-of-choice for terrestrial UHF broadcast applications due to the IOT's high efficiency with linearity and compact size. The accelerator community is also making the transition to IOT technology for a number of high-power UHF and L-band applications as a result of these benefits. Although the IOT appears to be quite simple, the actual operation of the device is quite complex and difficult to analyze quantitatively. Consequently, we are investigating the physics of the beam-wave interaction of the IOT with the goal of achieving significantly higher power operation. The time-domain electrostatic PIC code MICHELLE, in conjunction with the Analyst® suite of electromagnetic codes, were used to model the cathode-grid-anode structure that comprise the input cavity. Our investigation has led to the discovery of a mechanism responsible for intra-bunch charge formation. Time-domain PIC results of this effect will be shown. We will also present simulation results of the large-signal beam wave interaction in the output cavity using the code TESLA. Examples of single beam and multiple-beam (MB) IOT designs will also be shown.