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Beam lifetime and beam brightness in ALS

Conference ·
OSTI ID:108179
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=ll 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 {approximately}200% in beam lifetime by operating at the betatron coupling resonance.
Research Organization:
Lawrence Berkeley Lab., CA (United States)
Sponsoring Organization:
USDOE, Washington, DC (United States)
DOE Contract Number:
AC03-76SF00098
OSTI ID:
108179
Report Number(s):
LBL--36440; CONF-950512--320; LSGN--195; ON: DE96000143
Country of Publication:
United States
Language:
English

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