A New Design for A Super-Conducting Cavity Input Coupler

Abstract

An attractive structure using capacitive coupling has been found for the input coupler for the 45 MV/m versions of the International Linear Collider (ILC) project. The coupler supports an electrical field gradient of ~1 kV/m around the rf window ceramic with 500 kW through power, a VSWR of 1.1 and an overall frequency bandwidth of 100 MHz. No unwanted resonances were found in the rf window near the first and second harmonics of the operation frequency.

Design of a capacitive main power coupler for RF superconducting accelerators

“…To improve the performance and reduce the costs, we have designed a new coupler to replace the old one used in the PKU 1.5 cell DC-SC injector. We are confident of the new structure as there has been a report of successful sample [2] .…”

Breakdown in ceramic window

“…This type of window is developed at KEK [8] that presents better isolation from room temperature as there is no physical contact between the inner conductor and the ceramic. The gap between ceramic disk and inner conductor is ~4 mm (see Fig.…”

“…We have adapted a disk type ceramic window design. Two types of ceramic window designs, viz., a choke type [7] and a capacitive type [8], are optimized and their performance is compared in terms of bandwidth, ease of fabrication and the power handling capacity.…”