There is an increased need for high?power UHF microwave amplifiers for scientific, medical, industrial and military applications with improved overall efficiency. Existing amplifier technology can provide up to a megawatt of power with electronic efficiencies in the range from 65% to 70% for a single amplifier, and in some special cases efficiencies in the mid 70% range. However the power consumed by ancillary hardware is generally not included in these efficiency values; i.e., in the case of vacuum electronics, the electromagnet and cathode filament. The goal of this effort is to provide a high?power microwave amplifier within the UHF frequency band with overall efficiencies of 80% or higher, with power levels approaching a megawatt from a single device. We are proposing the development an advanced Multi?Stage Depressed Collector (MSDC) Multiple?Beam (MB) Inductive Output Tube (IOT) to meet these challenging efficiency requirements. We will design, fabricate and test a prototype three electron beam MSDC MB IOT capable of providing 250 kW continuous wave radio frequency (RF) power at a frequency of 591 MHz. Key to meeting or exceeding the 80% overall efficiency is the use of permanent magnet (PM) focusing, eliminating the power consumed by the electromagnet typically used for these devices. This prototype will be the first of its kind to combine MSDC MB IOT and PM technologies in a single device at this power level. We will use an array of simulation tools to perform end?to?end modeling and simulation for this advanced MSDC MB IOT design with overall efficiencies greater than 80%. The Phase 1 effort will focus on the electrical and mechanical design of this device, with the work for these efforts equally weighted. The electrical design phase will optimize the input cavity density modulated beam formation process, output cavity RF power extraction, and the PM focusing beam transport system. Energy recovery will be achieved with the use of a five electrode MSDC. Solid models will be created from the results of the electrical design phase to create a mechanical design package of the MSDC MB IOT, in anticipation of the build in Phase 2 of the program. High power radio frequency and microwave sources are employed in a wide range of applications. They are used to drive large?scale accelerators at DOE science facilities, as well as compact linear accelerators for industrial and medical uses, including radiation therapy. They are crucial in communications systems and electronic countermeasures, as well as in fundamental energy research. The development of a low cost, compact, high efficiency source will push forward the state of the art in each of these areas, by reducing energy costs at large scale facilities, improving the efficiency and reducing the size of compact accelerators, and making these type of devices more accessible to the consumer through a reduction in manufacturing costs and infrastructure requirements associated with conventional amplifiers.
