| Paper |
Title |
Page |
| MPPP042 |
Landau Damping of the Weak Head-Tail Instability at Tevatron
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2714 |
| |
- P.M. Ivanov, Y. Alexahin, J. Annala, V. Lebedev, V.D. Shiltsev
Fermilab, Batavia, Illinois
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Landau damping of the head-tail modes in Tevatron beam with the help of octupole-generated betatron tune spreads permits to reduce chromaticity from 15-20 units to zero thus significantly improving the beam lifetime. The octupole strengths have been experimentally optimized at different stages of the Tevatron operation, from proton injection to collision. Predictions of the analytical Landau damping model are compared with the experimental results.
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| MPPP043 |
Betatron Tune Spread Generation and Differential Chromaticity Control by Octupole at Tevatron
|
2756 |
| |
- P.M. Ivanov, Y. Alexahin, J. Annala, V. Lebedev
Fermilab, Batavia, Illinois
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Application of octupoles for Landau damping of the unstable head-tail modes requires careful consideration at their combination into separate families to insure maximum effectiveness and avoid degradation of the dynamic aperture due to the non-linear magnetic fields. Existing octupolar magnets around the machine have been arranged into four functional families with individual power supplies. Two of these families generate betatron tune spreads in the vertical and horizontal planes whereas the other two control the differential chromaticity between the proton and antiproton helices. The calculated effect on tunes and chromaticity is compared with direct measurements. Analytical formulas for betatron tune spectral density functions are presented.
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