Adjustable High Power Coax RF Coupler without Moving Parts

Period of Performance: 01/01/2011 - 12/31/2011


Phase 1 STTR

Recipient Firm

Muons, Inc.
552 North Batavia Avenue Array
Batavia, IL 60510
Principal Investigator
Firm POC

Research Institution

Argonne National Laboratory
9700 South Cass Avenue
Lemont, IL 60439


A 200 kW CW fundamental RF power coupler (FPC) with an adjustable in situ coupling factor would be highly desirable for a number of applications; for example, the 352 MHz light source at APS. The normal process of adjusting the coupling by rotational movement usually requires breaking the vacuum between the coupler and the RF cavity resulting in prolonged down-times and the risk of introducing contaminants into the vacuum system. We propose a novel system for adjusting the coupling coefficient of coaxial couplers to allow for individual control and adjustments to the RF fields under different beam loading scenarios. The RF coupler has no movable parts and relies on a ferrite tuner assembly, coax TEE, and double windows to provide a VSWR of better than 1.05:1 and a bandwidth of at least 8% at 1.15:1. The ferrite tuner assembly on the stub end of the coax TEE uses an applied DC magnetic field to change the Qext and the rf coupling coefficient, between the rf input and the cavity. A prototype assembly will be constructed using coax windows developed by Muons, Inc. and a ferrite tuner assembly constructed with 3 inch coax and tested at low power to verify the RF coupler characteristics and heat dissipation in the components of the coupler. The entire RF coupler will have no movable parts, and it will be constructed in a uniform coax line without matching elementsCommercial Applications and Other Benefits: as described by the applicant. (Limit to space provided). A high power coaxial RF coupler with variable coupling without moving parts is an extremely important innovation that reduces the mechanical complexity of couplers and significantly increases their reliability