[SLAC] [SLAC Pubs and Reports]

SLAC-PUB-7979
Calculation of Impedance from Multibunch Synchronous Phases: Theory and Experimental Results

Abstract

A novel beam-based method for measuring the longitudinal impedance spectrum is demonstrated using experimental data from the PEP-II High Energy Ring (HER). The method uses a digital longitudinal feedback system from which the charge and synchronous phase are measured for every bucket. Calculation of the transfer function from fill shape to synchronous phase yields the impedance seen by the beam at revolution harmonics. The experimentally-derived longitudinal impedance function and lab measurements of the impedance of parked RF cavities are compared to suggest a mechanism for the occasional instability of low-order coupled bunch modes observed in the HER during commissioning in October 1997.

Full Text

PDF

Compressed PostScript

Notes

The PDF version of this document was distilled from a PostScript file most likely created from LaTeX source which used Type 3 fonts. The resultant PDF may be unreadable on the screen at the default viewing magnification (fonts will appear bitmapped, jagged), though the type will be legible at higher magnifications.

Despite the cosmetic problems resulting from the use Type 3 fonts in the original source file, such PDF files print without problems; likewise, the onscreen text is searchable and selectable.

More Information

Full bibliographic data for this document, including its complete author list, is (or soon will be) available from SLAC's SPIRES-HEP Database.

Please report problems with this file to posting@slac.stanford.edu. The SLAC preprint inventory is provided by the SLAC Technical Publications Department.
Page generated 04 Apr 2001 @ 15:08 PDT by htmlme.pl