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Title: 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.

Authors:
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE Office of Energy Research (ER) (US)
OSTI Identifier:
9945
Report Number(s):
SLAC-PUB-7979
TRN: US0103240
DOE Contract Number:  
AC03-76SF00515
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 20 Oct 1998
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; PEP STORAGE RINGS; FEEDBACK; HARMONICS; IMPEDANCE; INSTABILITY; TRANSFER FUNCTIONS; BEAM BUNCHING

Citation Formats

Prabhakar, Shyam. Calculation of Impedance from Multibunch Synchronous Phases: Theory and Experimental Results. United States: N. p., 1998. Web. doi:10.2172/9945.
Prabhakar, Shyam. Calculation of Impedance from Multibunch Synchronous Phases: Theory and Experimental Results. United States. https://doi.org/10.2172/9945
Prabhakar, Shyam. 1998. "Calculation of Impedance from Multibunch Synchronous Phases: Theory and Experimental Results". United States. https://doi.org/10.2172/9945. https://www.osti.gov/servlets/purl/9945.
@article{osti_9945,
title = {Calculation of Impedance from Multibunch Synchronous Phases: Theory and Experimental Results},
author = {Prabhakar, Shyam},
abstractNote = {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.},
doi = {10.2172/9945},
url = {https://www.osti.gov/biblio/9945}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Oct 20 00:00:00 EDT 1998},
month = {Tue Oct 20 00:00:00 EDT 1998}
}