S-Band vacuum loads at the SLAC linac are encountering operational problems, now that they have to operate under the stringent requirements of the LCLS: 50 MW peak power, 6 kW average power, and extremely-tight phase stability for the linac. Failure mechanisms have been studied which suggest an RF surface breakdown of the 200 um Kanthal layer.

We propose a novel solution which incorporates mode conversion from TE10 in rectangular waveguide to TE01 in round waveguide. Lossy material will be placed in the round waveguide, and the selection of the TE01 mode minimizes the electric field normal to the surface of the lossy material. This lossy material in the TE01 round waveguide will be mechanically confined in compression (without brazing), in order to eliminate tensile stresses in the lossy material. The wrap-around mode converter will be based upon the X-band mode converter invented at SLAC, and the TE01 waveguide load design will be based upon HOM load designs developed by Muons, Inc.
A low-power prototype assembly will be constructed based upon the design developed during the Phase I program. The mode converter will be designed and fabricated. The TE01 load will also be designed and fabricated, after materials testing to help select the best lossy material for this application.

Operational improvements to the SLAC LCLS linac will require the replacement of over 1000 vacuum loads. The new design can be scaled for use at other frequencies in a multitude of commercial RF applications. Muons, Inc. has negotiated an agreement with a manufacturing firm, XXX to be the Manufacturing Partner for the commercialization of this technology.