| DATE: |
2006-05-11 13:30 - 15:30 |
| PLACE: |
Room 203 in the building 2, 2nd floor |
| TITLE: |
Accelerator Physics Seminar [ Emittance growth and instabilities induced by electron cloud ] |
| CONTACT: |
ohmi post.kek.jp |
| LANGUAGE: |
English |
| ABSTRACT: |
An electron cloud (EC) can build-up in the vacuum chamber of proton and positron storage rings, interact with the beam and give rise to instabilities and emittance growth. This talk presents numerical and analytical studies of transverse single-bunch effects induced by the electron cloud.
The strong head-tail instability threshold and the associated fast emittance growth are studied as a function of beam and cloud characteristics, with a special attention to the CERN LHC and SPS rings, and the results are compared with analytical models.
A mechanism for the slow incoherent emittance growth, which is still present at cloud densities below the instability threshold, is proposed as one caused by the periodic crossing of resonances, as a combined effect of particles synchrotron motion and EC induced tune-shift variation along the bunch.
Finally, preliminary simulations for KEKB LER are shown, trying to reproduce the observed vertical betatron sidebands.
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