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Title |
Other Keywords |
Page |
| TUAX04 |
Test of a prototype active damping system for the e-p instability at the LANL PSR
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feedback, kicker, electron, impedance |
94 |
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- R. J. Macek, R. C. McCrady, S. B. Walbridge, J. Zaugg
LANL, Los Alamos, New Mexico
- S. Assadi, C. Deibele, S. Henderson, M. A. Plum
ORNL, Oak Ridge, Tennessee
- J. M. Byrd
LBNL, Berkeley, California
- M. T.F. Pivi
SLAC, Menlo Park, California
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Our collaboration from LANL, SNS, LBNL and SLAC has developed and successfully tested a prototype of an analog, transverse (vertical) feedback system for active damping of the two-stream (e-p) instability at the Los Alamos Proton Storage Ring (PSR). This system was able to improve the instability threshold (as measured by the RF buncher voltage) by ~30%. Beam leakage into the gap at lower RF buncher voltage and resulting higher growth rates from more trapped electrons is the likely cause of this limitation. We will describe the system configuration and results of several experimental tests of system performance. We will also discuss our studies and analysis of the factors limiting system performance.
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| TUBX02 |
Collective Transverse Instabilities in the GSI Synchrotrons
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simulation, space-charge, octupole, impedance |
131 |
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- V. Kornilov, O. Boine-Frankenheim, I. Hofmann
GSI, Darmstadt
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One of the primary challenges for the design of the FAIR synchrotrons at GSI Darmstadt is the high current operation close to the stability limits, with small tolerable beam losses. Collective instabilities are a potential limiting factor for the performance of the rings. We discuss results of experimental and numerical investigations of transverse collective beam behavior in the SIS 18 synchrotron. Also damping mechanisms in the presence of space charge, including the linear Landau damping and decoherence due to nonlinearities are discussed. These are the essential factors to define impedances budgets for the GSI synchrotrons. As a computational tool accounting the beam nonlinear dynamics with impedances and self-consistent space charge, the particle tracking code PATRIC is used.
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| TUBX06 |
Betatron Tune Shift due to Nonlinear Resistive-Wall Wake Field
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emittance, impedance, betatron, dipole |
159 |
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- F. Zimmermann
CERN, Geneva
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I present formulae for the coherent and incoherent tune shifts of a single bunch traveling between two parallel resistive plates. It is shown that for the parameters of an LHC prototype collimator in the SPS, both the nonlinear wake-field components, calculated by Piwinski, and the correct time dependence, e.g., as derived by Burov and Lebedev, must be taken into account.
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| WEBY04 |
Refined Models of Intrabeam Scattering
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scattering, proton, emittance, coupling |
265 |
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- F. Zimmermann, F. Ruggiero
CERN, Geneva
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We discuss two extensions of intrabeam-scattering theory. First, starting from the Bjorken-Mtingwa recipe, general formulae are derived for the three electro-magnetic intrabeam scattering growth rates, including non-ultrarelativistic terms and vertical dispersion, but maintaining a Gaussian beam approximation. A few applications demonstrate the importance of the vertical dispersion. Second, aside from electromagnetic interactions, hadrons may also undergo nuclear scattering off each other. We estimate the magnitude of this process, and argue that the loss rate due to “nuclear intrabeam scattering” could become significant in high-energy proton or ion storage rings, such as the LHC.
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