Beam lifetime and beam brightness in ALS

Author

Kim, C. ; Jackson, A. ; Warwick, A.

Author_Institution

Lawrence Berkeley Lab., CA, USA

Volume

1

fYear

1995

Firstpage

198

Abstract

Beam lifetime in ALS is dominated by the Touschek scattering. Measurements of lifetime in single-bunch mode with estimates of bunch dimensions obtained from undulator radiation data are consistent with expectations (t=1.8 hours at 1.25 mA per bunch). However, the lifetime is significantly longer in multi-bunch mode (t=11 hours at 400 mA per 320 bunches). This discrepancy has been traced to an increase in the momentum spread and bunch length in the beam caused by longitudinal coupled-bunch motions driven by higher-order modes in the rf cavities. The increased momentum spread leads to a significant degradation in the undulator spectral performance. Feedback stabilization of the coupled-bunch motion improves the spectral characteristics of the undulator beam at the expense of beam lifetime. We observe an increase of ~200% in beam lifetime by operating at the betatron coupling resonance

Keywords

beam handling techniques; electron accelerators; electron beams; particle beam diagnostics; particle beam dynamics; particle beam stability; storage rings; 1.8 hour; ALS; Advanced Light Source; RF cavities; Touschek scattering; beam brightness; beam lifetime; betatron coupling resonance; bunch dimensions; bunch length; higher-order modes; longitudinal coupled-bunch motions; momentum spread; multibunch mode; single-bunch mode; spectral characteristics; undulator radiation data; Brightness; Compaction; Current measurement; Feedback; Light scattering; Optical coupling; Particle scattering; Resonance light scattering; Storage rings; Undulators;

fLanguage

English

Publisher

ieee

Conference_Titel

Particle Accelerator Conference, 1995., Proceedings of the 1995

Print_ISBN

0-7803-2934-1

Type

conf

DOI

10.1109/PAC.1995.504608

Filename

504608