Observations of bunch lengthening effects in the APS 7-GeV storage ring
- Argonne National Lab., IL (US). Advanced Photon Source
Measurements of the bunch length and horizontal beam size at a dispersive point in the lattice versus single-bunch current have been done on the Advanced Photo Source (APS) 7-GeV storage ring. These data are relevant to issues (limits) of obtaining high peak currents for storage-ring-based FELs. Bunch lengths from {sigma}{sub {tau}} {approx} 25 to 70 ps were measured using a Hamamatsu C5680 dual-sweep streak camera. Additional complementary data on energy spread deduced from horizontal beam size at a dispersive point in the lattice were also tracked versus single-bunch current. Both optical synchrotron radiation (OSR) and x-ray synchrotron radiation (XSR) techniques were used. For the set of data taken at a synchrotron frequency of 1.2 kHz (indicating rf gap voltage {<=} 6 MV), the significant bunch lengthening without a comparable horizontal size change ({Delta}E growth) is consistent with the potential well distortion model rather than the predictions of a microwave instability calculation. With higher rf gap voltage, peak currents up to 400 A were observed. A bunch-lengthening effect in multibunch mode was also observed as the stored-beam current approached the available rf power limit.
- Research Organization:
- Argonne National Lab., IL (US)
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (US)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 432947
- Report Number(s):
- ANL/ASD/CP--90147; CONF-9608133--15; ON: DE97001012
- Country of Publication:
- United States
- Language:
- English
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