Ferroelectric Based High Power Components for L-Band Accelerator Applications

Fast electronic tuning of SC cavities is a critical issue for optimized rf power distribution for accelerators. The overall goal of the program is to develop an L-band externally-controlled fast ferroelectric tuner for controlling the coupling of superconducting RF cavities for the future linear colliders. Recently proposed planar tuner design requires new elements to be developed made of an improved new ferroelectric material with a low microwave loss. Applying a bias voltage across a nonlinear ferroelectric changes its permittivity. These new ferroelectric elements are to be designed for the fast active tuner for SC cavities that can operate in air at low biasing DC fields. The principal goal of Phase I of the project is to develop new BST-based elements, HV-proof with a robust gold deposition providing solid DC bias contacts. Dielectric constant tuning will be in the range of 5-6% at 15 kV/m electric field. The field can be applied in air. The ferroelectric elements will be developed with a loss tangent required for overall fast ferroelectric tuner losses in the range of & lt; 10%. The brazing technology providing HV joints of the gold layers deposited on the ferroelectric surface with the HV bias field copper contacts will be developed along with the HV triple point protection. Commercial Applications and benefits: The ILC project is a 0.5 1.0 TeV collider realized through use of superconducting rf technology operated at L-band (1300 MHz). For this approach, the RF power will be generated by about 280 klystrons per linac, each feeding 26 nine-cell cavities. Any technological developments to reduce power requirements should be beneficial for this project. The fast ferroelectric tuners appear to have the capability of reducing the cavity filling time and thus conserve RF power. The maximum total AC power savings for the ILC project could be up to ~8 MW. The new ferroelectric components will definitely find a variety of large- signal commercial and military applications like radar antenna elements, electrically-controlled phase shifters and switching devices.