Status of X-band Standing Wave Structure Studies at SLAC

The linacs proposed for the Next Linear Collider (NLC) and Japanese Linear Collider (JLC) would contain several thousand X-Band accelerator structures that would operate at a loaded gradient of 50 MV/m. An extensive experimental and theoretical program is underway at SLAC, FNAL and KEK to develop structures that reliably operate at this gradient. The development of standing wave structures is a part of this program. The properties of standing wave structures allow them to operate at the loaded gradient in contrast to traveling wave structures that need conditioning to the unloaded gradient (65 MV/m for NLC/JLC). The gradients in the standing structures tested thus far have been limited by input coupler breakdowns. The behavior of these breakdowns is consistent with a model of pulsed heating due to high magnetic fields. New input couplers have been designed to reduce maximum magnetic fields. This paper discusses design considerations related to high power performance, wakefield suppression and results of high power tests of prototype standing wave structures. Paper presented at the 2003 Particle Accelerator Conference ( PAC 03) Portland, Oregon, USA, May 12 16, 2003 Work supported by the U.S. Department of Energy contract DE-AC03-76SF00515. STATUS OF X-BAND STANDING WAVE STRUCTURE STUDIES AT SLAC V.A. Dolgashev, C. Adolphsen, D.L. Burke, G. Bowden, R.M. Jones, J. Lewandowski, Z. Li, R. Loewen, R.H. Miller, C. Ng, C. Pearson, R.D. Ruth, S.G. Tantawi, J.W. Wang, P. Wilson, SLAC, Stanford, CA 94309, USA