RF Breakdown in X-Band Waveguides

Next generation of linear accelerators will have multimegawatt rf systems. The RF system of the Next-Linear Collider (NLC) will have hundreds of waveguide components and high-gradient accelerating structures. Waveguide components should reliably handle up to 600 MW of a 400 ns, 11.424 GHz rf pulse [1]. RF breakdown at such high power could damage these components. For example, breakdown damage is a major issue for long term operation of high-gradient accelerating structures [2]. An extensive experimental and theoretical program to study phenomena of rf breakdown is under way in SLAC. This work is a part of this program. Our experiments with rf breakdowns in a copper low-magnetic field waveguide are described in [3]. Here we discuss study of a copper high-magnetic-field waveguide and a low-magnetic-field waveguide with walls made of copper, gold and stainless steel. All experiments are done at a frequency of 11.424 GHz.