Commissioning experience from PEP-II HER longitudinal feedback

Conference · Mon Jun 01 00:00:00 EDT 1998

DOI:https://doi.org/10.1063/1.57037· OSTI ID:674792

Prabhakar, S; Teytelman, D; Fox, J; Young, A; Corredoura, P; Tighe, R

The DSP-based bunch-by-bunch feedback system installed in the PEP-II HER has been used to damp HOM-induced instabilities at beam currents up to 6-5 mA during commissioning. Beam pseudospectra calculated from feedback system data indicate the presence of coupled bunch modes that coincide with the 0-M-2 cavity HOM. Bunch current and synchronous phase measurements are also extracted from the data. These measurements reveal the impedance seen by the beam at revolution harmonics. The impedance peak at 3*frev indicates incorrect parking of the idle cavities, and explains the observed instability of mode 3. Bunch synchrotron tunes are calculated from lorentzian fits to the data. Bunch-to-bunch time variation due to the cavity transient is shown to be large enough to result in Landau damping of coupled bunch modes.

• Research Organization: Stanford Univ., Stanford Linear Accelerator Center, CA (US)
• Sponsoring Organization: USDOE Office of Energy Research, Washington, DC (US)
• DOE Contract Number: AC03-76SF00515
• OSTI ID: 674792
• Report Number(s): SLAC-PUB--7849; CONF-980573--; ON: DE98059235
• Resource Type: Conference paper/presentation
• Conference Information: 8. beam instrumentation workshop (BIW-98), Stanford, CA (US), 05/04/1998--05/07/1998
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
BEAM CURRENTS
CAVITIES
COMMISSIONING
FEEDBACK
HARMONICS
IMPEDANCE
INSTABILITY
LANDAU DAMPING
SYNCHROTRONS
TRANSIENTS