| Paper |
Title |
Page |
| TUAX03 |
Beam loss, emittance growth and halo formation due to the pinched electron cloud
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84 |
| |
- E. Benedetto, F. Zimmermann
CERN, Geneva
- G. Franchetti
GSI, Darmstadt
- K. Ohmi
KEK, Ibaraki
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Electron cloud can cause beam losses and emittance growth in proton or positron storage rings. If the electron density exceeds a certain threshold value, a strong head-tail instability manifests itself, characterized by a rapid beam-size blow-up with a rise time comparable to the synchrotron period. However, even for densities below the coherent-instability threshold, the electron-cloud can give rise to a significant emittance growth. We identified the mechanism for this incoherent growth as one caused by the combined effect of the beam particles synchrotron motion and the longitudinal variation of the tune shift, which is proportional to the pinched electron-cloud distribution along the bunch. This can give rise to the periodic crossing of a resonance, in analogy to halo formation in space-charge dominated beams, or eventually, if the tune shift is sufficiently large, to the crossing of bunch regions where the single-particle motion is linearly unstable.
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| THAW06 |
Electron cloud effect in J-PARC
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0 |
| |
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We discuss electron cloud instability in J-PARC proton rings. Instabilities in both of bunched and coasting beam are treated.
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