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| DYN01 |
Numerical Modeling of E-Cloud Driven Instability and its Mitigation using a Simulated Feedback System in the CERN SPS
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- J. Vay, J. Byrd, M. Furman, R. Secondo, M. Venturini
LBNL
- J. Fox, C. Rivetta
SLAC National Accelerator Laboratory
- W. Hofle
CERN
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Funding: Supported by the US-DOE under Contract DE-AC02-05CH11231, the US-LHC Accelerator Research Program (LARP) and the SciDAC program ComPASS. Used resources of NERSC and the Lawrencium cluster at LBNL.
Electron clouds impose limitations on current accelerators that may be more severe for future machines, unless adequate measures of mitigation are taken. Recently, it has been proposed to use feedback systems operating at high frequency (in the GHz range) to damp single-bunch transverse coherent oscillations that may otherwise be amplified during the interaction of the beam with ambient electron clouds. We have used the simulation package WARP-POSINST to study the growth rate and frequency patterns in space-time of the electron cloud driven transverse instability in the CERN SPS accelerator with, or without, feedback models (with various levels of idealization) for damping the instability. We will present our latest simulation results, contrast them with actual measurements and discuss the implications for the design of the actual feedback system. More simulations results are presented by Raffaello Secondo using a Finite Impulse Response (FIR) as processing channel in a more realistic, albeit yet highly simplified, model of feedback control system.
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Slides
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| DYN02 |
Simulated Performance of an FIR-Based Feedback System to Control the Electron Cloud Single-Bunch Transverse Instabilities in the CERN SPS
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- R. Secondo, J. Byrd, M. Furman, M. Venturini, J. Vay
LBNL
- J. Fox, C. Rivetta
SLAC National Accelerator Laboratory
- W. Hofle
CERN
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The performance of High Energy proton machines like the SPS at CERN is affected by transverse single-bunch instabilities due to the Electron Cloud effect. In a first step to model a Feedback control system to stabilize the bunch dynamics, we use a Finite Impulse Response filter to represent the processing channel. The effect of this simplified processing channel in the bunch dynamics is analyzed using the simulation package WARP-POSINST. We report on simulation results, discuss the basic features of the feedback model and present our plans for further development of the numerical models used in the simulations.
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Slides
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| DIA01 |
TE Wave Measurements at Cesr-TA
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- S. De Santis, J. Byrd, G. Penn
LBNL
- J. Sikora
Cornell University - CLASSE
- K. Hammond
Harvard University
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TE wave transmission is currently used as a diagnostic tool for measurements of the electron cloud density in several regions of the Cesr-TA ring. While the method is conceptually well established, a number of effects contribute to making a quantitative estimate of the density not straightforward. We report on the measurements currently performed during Cesr-TA experimental runs, describe experimental challenges, and the methods devised to analyze and solve them.
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Slides
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