| Paper |
Title |
Page |
| PST03 |
Methods for Quantitative Interpretation of Retarding Field Analyzer Data
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91 |
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- J. Calvey, J. Crittenden, G. Dugan, M. Palmer
Cornell University - CLASSE
- K. Harkay
Argonne National Laboratory
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A great deal of Retarding Field Analyzer (RFA) data has been taken as part of the CesrTA program at Cornell. Obtaining a quantitative understanding of this data requires use of cloud simulation programs, as well as a detailed model of the RFA itself. In some cases the RFA can be modeled by postprocessing the output of a simulation codes, and one can obtain “best fit” values for important simulation parameters using a systematic method to improve agreement between data and simulation. In other cases, in particular in high magnetic field regions, the presence of the RFA can have an effect on the cloud, and one needs to include a model of the RFA in the simulation program itself.
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| PST09 |
Electron Cloud Modeling Results for Time-Resolved Shielded Pickup Measurements at CesrTA
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123 |
| |
- J. Crittenden, Y. Li, X. Liu, M. Palmer, J. Sikora
Cornell University - CLASSE
- S. Calatroni, G. Rumolo
CERN
- N. Omcikus
University of California at Los Angeles
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The Cornell Electron Storage Ring Test Accelerator (CesrTA) program includes investigations into electron cloud buildup, applying various mitigation techniques in custom vacuum chambers. Among these are two 1.1-m-long sections located symmetrically in the east and west arc regions. These chambers are equipped with pickup detectors shielded against the direct beam-induced signal. They detect cloud electrons migrating through an 18-mm-diameter pattern of holes in the top of the chamber. A digitizing oscilloscope is used to record the signals, providing time-resolved information on cloud development. Carbon-coated, TiN-coated and uncoated aluminum chambers have been tested. Electron and positron beams of 2.1, 4.0 and 5.3 GeV with a variety of bunch populations and spacings in steps of 4 and 14 ns have been used. Here we report on results from the ECLOUD modeling code which highlight the sensitivity of these measurements to model parameters such as the photoelectron azimuthal and energy distributions at production, and the secondary yield parameters including the true secondary, rediffused, and elastic yield values. In particular, witness bunch studies exhibit high sensitivity to the elastic yield by providing information on cloud decay times.
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| PST10 |
Using Coherent Tune Shifts to Evaluate Electron Cloud Effects on Beam Dynamics at CesrTA
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130 |
| |
- D. Kreinick, J. Crittenden, G. Dugan, Z. Leong, M. Palmer
Cornell University - CLASSE
- R. Holtzapple, M. Randazzo
California Polytechnic State University
- M. Furman, M. Venturini
LBNL
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One technique used at CesrTA for studying the effects of electron clouds on beam dynamics is to measure electron and positron bunch tunes under a wide variety of beam energies, bunch charge, and bunch train configurations. Comparing the observed tunes with the predictions of various simulation programs allows the evaluation of important parameters in the cloud formation models. These simulations will be used to predict the behavior of the electron cloud in damping rings for future linear colliders.
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