RF breakdown experiments at SLAC

Summary form only given. The Next Linear Collider (NLC) design that is a currently being developed at Stanford Linear Accelerator Center (SLAC) requires the X-band RF structures to support significant RF electric fields. The klystron RF sources for the NLC require lower E fields but also have lower breakdown thresholds. The goals of the program are to improve RF breakdown thresholds, to identify the cause of the lower breakdown thresholds in klystron cavities vs accelerator cavities, and to develop a set of protocols for manufacturing that will yield the highest breakdown levels for all NLC components. SLAC´s X-band resonant ring is being used to test a series of RF breakdown cavities. Early tests were performed on a series of TM/sub 010/ cavities. A new TM/sub 020/ cavity has been designed with demountable noses that will allow accurate, pre and post breakdown evaluation of the high field surfaces. A gated CCD camera and X-ray scintillator will image the breakdown surfaces through a tungsten pinhole in the outer wall of the cavity.