Fast Ferroelectric L-Band Tuner for ILC Cavities

The international accelerator community is focused on the development of the next electron-positron collider, the International Linear Collider (ILC), which will be based on superconducting radio frequency (RF) technology. This project will develop a fast ferroelectric tuner for ILC cavities. The tuner will permit adjustments, during each RF pulse of cavity coupling, to compensate for unavoidable microphonics and Lorentz force detunings, and to reduce the total RF power needed. As a result, a number of benefits will accrue: (1) the refrigeration power needed to remove waste heat from the cavities will be reduced, (2) the cavity can remain on resonance at the operating frequency and maintain precise phase, and (3) both the cavity filling and decay times can be shortened. In Phase I, the design of a coaxial phase shifter for the L-band tuner for ILC cavities was completed. The design included specifications for a ferroelectric ring and alumina rings, a coaxial impedance transformer, a waveguide-to-coax coupler, thermal considerations, and temperature stabilization requirements. In Phase II, the L-band coaxial phase shifter for the tuner will be fabricated and tested at Fermi National Accelerator Laboratory. Commercial Applications and Other Benefits as described by the awardee: A fast ferroelectric tuner would be needed for each of the 10,000 superconducting cavities of the ILC. In mass production, a tuner price of $500 should be achieved, yielding a potential market in the range of $5 milliion. Other applications are envisioned in other accelerators, including industrial machines, increasing the size of the potential market.