Calculation of Impedance from Multibunch Synchronous Phases: Theory and Experimental Results

Technical Report · Tue Oct 20 00:00:00 EDT 1998

DOI:https://doi.org/10.2172/9945· OSTI ID:9945

Prabhakar, Shyam

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.

• Research Organization: SLAC National Accelerator Lab., Menlo Park, CA (United States)
• Sponsoring Organization: USDOE Office of Energy Research (ER) (US)
• DOE Contract Number: AC03-76SF00515
• OSTI ID: 9945
• Report Number(s): SLAC-PUB-7979; TRN: US0103240
• Resource Relation: Other Information: PBD: 20 Oct 1998
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
PEP STORAGE RINGS
FEEDBACK
HARMONICS
IMPEDANCE
INSTABILITY
TRANSFER FUNCTIONS
BEAM BUNCHING