KA-Band Resonant Ring for High-Power Testing of Accelerator Components

72315S03-I The development of millimeter-wave accelerator technology not only would provide an increase in acceleration gradient, as predicted by accepted scaling laws, but also would increase the final energy for a given overall accelerator length. Thus, where the Next Linear Collider operating at 11.424 GHz would have an unloaded acceleration gradient, G = 77 MeV/m, and two acceleration lengths, L = 6 km, for a center-of-mass energy of W = 0.5 TeV, a future collider could be expected to operate at 34.272 GHz with G = 200 MeV/m, W = 4 TeV, and L = 12 km. Achieving this goal will require a new high-power 34-GHz amplifier (a magnicon), accelerator structures, and ancillary radio frequency (RF) components; and the testing of these components will require a high-power resonant ring. Therefore, this project will develop a four-mirror ring resonator, designed and built for operation at 34 GHz. It will be based on use of the TF0l mode in an oversized circular waveguide, and will have three miter bends and one partially-transparent planar coupling mirror. With an anticipated effective power gain of 10-20, this ring is expected to enable tests at power levels equivalent to 100s of MW, when driven with output from a 40-50 MW, 34 GHz magnicon. Phase I will design components for incorporation into the resonant ring (including miter bends, mode converters, adjustable tuning bellows, and a partially-transparent planar coupling mirror), and cold-test measurements will be conducted. A preliminary engineering design will be made for a high-power version of the ring to be built in a follow-on Phase II project. Commercial Applications and Other Benefits as described by the awardee: Should a future multi-TeV collider be built that is based on 34-GHz technology, demand would exist for thousands of components, each of which would require high-power testing using the resonant ring.