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XX International Linac Conference

TUA07 (Poster)

Presenter: Roger Jones (SLAC)
Status: Complete
FullText: pdf
Eprint: physics/0008198

Fabrication and Tolerance Issues and Their Influence on Multibunch BBU and Emittance Dilution in the Construction of X-Band RDDS Linacs for the NLC*


We explore the effects of errors in the fabrication of several thousand RDDS (Rounded Damped Detuned Structure [1]) linacs on the emittance dilution and, when severe errors are present, on BBU (Beam Break Up). Multiple bunches are accelerated within a pulse train. Fabrication errors which give rise to errors in the modal frequencies which are both randomly distributed and systematically shifted from structure-to -structure are considered. Should a systematic shift in the mode frequencies occur repeatably from structure-to-structure then BBU may occur. However, provided the errors in the frequencies are distributed randomly from cell-to-cell and from structure-to-structure then the emittance is actually improved slightly over that of the purely single bunch emittance. Results are presented on the emittance growth and phase space for small errors and for relatively large errors (introduced with a view to relaxing the tolerance requirements).
[1] R.M.Jones et al, 'The Transverse Long-Range Wakefield in RDDS1 for the JLC/NLC X-Band Linacs', Proc IEEE 1999 Particle Accelerator Conference (PAC99),p3468,(1999)
*Work supported at SLAC under U.S. Department of Energy grant number DE-AC03-76SF00515.

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