SBIR-STTR Award

Conventional waveguide windows have power-handling limitations that severely restrict linear accelerator performance. This project will develop a novel microwave window concept that directly addresses the electrical and thermal stress limitations of conventional waveguide windows, leading to improvements in both peak and average power-handling capability. Phase I will develop a design theory for this new window concept and, as an example, provide a design for a specific linear accelerator application. In Phase II, a prototype high-power radio frequency window will be developed and tested at the linear accelerator laboratory for which the Phase I design example was created. Commercial Applications and Other Benefits as described by awardee: The microwave window should be readily implemented at linear accelerator laboratories that have an existing need for windows with higher power-handling capability

Conventional waveguide windows for extremely high-power microwave systems are close to their power-handling-capability limits. Further efforts along conventional lines invite problems with higher-order modes, thermal cooling, and thermo-mechanical stresses. The basic problem with the conventional approach is that the microwave power is forced through a single disk window. This project will develop a distributed microwave window concept in which the power is transmitted through a series of ceramic-filled apertures. In Phase I, mode-matching field theory and software were developed for both scattering parameter and trapped-mode characterization in the new window geometry. Mockup prototype windows were designed, fabricated, and tested at low-power, successfully demonstrating the suitability of the approach to high-power window design. Measured scattering parameters and mode resonance frequencies correlated well with calculated values, which demonstrated the technical feasibility of this microwave window. Phase II will develop additional theory and software for advanced compact configurations of the distributed window. Additional cold-test prototypes (non-brazed) will be designed, built, and tested at low-power. Commercial Applications and Other Benefits as described by awardee: The high-power microwave windows should find use in radar, fusion, and particle accelerator applications. Also, the dual injection feature of the distributed window lends would be useful for studying the nonlinear properties of the dielectric material used in the window’s ceramic-filled coupling apertures