| Paper |
Title |
Page |
| TUPCH200 |
Amplitude Linearizers for PEP-II 1.2 MW Klystrons and LLRF Systems
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1480 |
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- D. Van Winkle, J. Browne, J.D. Fox, T. Mastorides, C.H. Rivetta, D. Teytelman
SLAC, Menlo Park, California
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The PEP-II B-factory has aggressive current increases planned for luminosity through 2008. At 2.2 A (HER) on 4 A (LER) currents, longitudinal growth rates will exceed the damping rates achievable in the existing low level RF and longitudinal low mode feedback systems. Klystron gain non-linearity has been shown to be a key contributor to these increased growth rates through time domain non-linear modeling and machine measurements. Four prototype klystron amplitude modulation linearizers have been developed to explore improved linearity in the LLRF system. The linearizers operate at 475 MHz with 15 dB dynamic range and 1 MHz linear control bandwidth. Results from lab measurements and high current beam tests are presented. Future development progress and production designs are detailed.
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| THPCH101 |
Modeling and Simulation of Longitudinal Dynamics for LER-HER PEP II Rings
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3032 |
| |
- C.H. Rivetta, J.D. Fox, T. Mastorides, D. Teytelman, D. Van Winkle
SLAC, Menlo Park, California
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A time domain dynamic model and simulation tool for beam-cavity interactions in LER and HER rings at PEP II is presented. The motivation for this tool is to explore the stability margins and performance limits of PEP II LLRF systems at higher currents and upgraded RF configurations. It also serves as test bed for new control algorithms and to define the ultimate limits of the architecture. The tool captures the dynamical behavior of the beam-cavity interaction based on a reduced model. It includes nonlinear elements in the klystron and signal processing. The beam current is represented by macro-bunches. Multiple RF stations in the ring are represented via one or two single macro-cavities. Each macro-cavity captures the overall behavior of all the 2 or 4 cavity RF stations. This allows modeling the longitudinal impedance control loops interacting with the longitudinal beam model. Validation of simulation tool is in progress by comparing the measured growth rates for both LER and HER rings with simulation results. The simulated behavior of both machines at high currents are presented comparing different control strategies and the effect of non-linear klystrons and the linearizer.
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