Multiple Beam Power Grid Tubes for High Frequency and High Power Operation

There are no compact, high-power, high-efficiency RF sources in the 300 – 700 MHz frequency range for ion and proton accelerators and colliders.Inductive output tubes are unable to provide the power levels required, and klystrons are extremely large and expensive in this frequency range.Solid state sources are available, but are also very expensive, large, and inefficient.Calabazas Creek Research Inc.is developing multiple beam, triodes to produce high power RF in this frequency range.Triodes routinely provide RF power with high efficiency at these frequencies; however, current, single beam devices cannot provide the required power.This program is using modern, 3D analysis tools and techniques to dramatically increase the available power from triodes and achieve efficiencies exceeding 85%.The Phase I program investigated the design of multiple beam triodes that could drive RF sources between 350 – 700 MHz and produce powers of 200 kW.Both pulsed and continuous wave (CW) systems were investigated.Computational analysis indicates that devices providing the goal power can be economically built that will operate at efficiencies approaching 90%.Thermal analysis indicates that thermomechanical stresses are well below critical levels.Economic analysis indicates these sources will cost less than 10% that of comparable products.Multiple beam triodes will be built and tested in RF sources at 350 MHz and 700 MHz.Both low duty and CW triodes and RF sources will be investigated.Triodes, coupled with input and output cavities, are extremely compact, high efficiency sources of RF power.The first gridded tubes were developed more than a century ago; however, modern design codes and materials now provide resources to dramatically increase the power and frequency.The simple design will reduce the cost of RF sources for ion and proton accelerators for scientific, medical, and industrial applications.If successfully developed, they will provide the most compact, cost-effective RF sources in this frequency range.