Measurements of a Fast Vertical Instability in the PEP-II HER
- SLAC
The HER beam current was limited to tens of mA by a strong vertical coupled bunch instability during PEP-II commissioning in July '98. In the absence of transverse feedback, vertical oscillations were seen to be unstable at currents as low as 5 mA. The instability has been observed by using the HER longitudinal feedback electronics to digitize and store the vertical beam signal used for transverse feedback. This note presents measurements of modal growth and damping rates at two different vacuum pressures for 291 bunch uniform fills as well as 100 and 150 bunch train measurements. In some cases the unstable modes maintain a constant residual amplitude when feedback is on, and exhibit nonlinear behavior when feedback is switched off. Knowledge of the shape, speed and spectral location of the modal transients should help in diagnosing the cause of instability.
- Research Organization:
- Stanford Linear Accelerator Center, Menlo Park, CA (US)
- Sponsoring Organization:
- USDOE Office of Energy Research (ER) (US)
- DOE Contract Number:
- AC03-76SF00515
- OSTI ID:
- 763783
- Report Number(s):
- SLAC-AP-121
- Country of Publication:
- United States
- Language:
- English
Similar Records
Multi-Bunch Instability Diagnostics via Digital Feedback Systems at PEP-II, DAFNE, ALS and SPEAR
Commissioning experience from PEP-II HER longitudinal feedback
Measurements of Transverse Coupled-Bunch Instabilities in PEP-II
Technical Report
·
Wed Apr 28 00:00:00 EDT 1999
·
OSTI ID:10064
Commissioning experience from PEP-II HER longitudinal feedback
Conference
·
Mon Jun 01 00:00:00 EDT 1998
·
OSTI ID:674792
Measurements of Transverse Coupled-Bunch Instabilities in PEP-II
Technical Report
·
Mon Apr 11 00:00:00 EDT 2005
·
OSTI ID:839845