Impedance computations and beam-based measurements: A problem of discrepancy

Smaluk, Victor

doi:10.1016/j.nima.2018.01.047

Title: Impedance computations and beam-based measurements: A problem of discrepancy

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Abstract

High intensity of particle beams is crucial for high-performance operation of modern electron-positron storage rings, both colliders and light sources. The beam intensity is limited by the interaction of the beam with self-induced electromagnetic fields (wake fields) proportional to the vacuum chamber impedance. For a new accelerator project, the total broadband impedance is computed by element-wise wake-field simulations using computer codes. For a machine in operation, the impedance can be measured experimentally using beam-based techniques. In this article, a comparative analysis of impedance computations and beam-based measurements is presented for 15 electron-positron storage rings. The measured data and the predictions based on the computed impedance budgets show a significant discrepancy. For this article, three possible reasons for the discrepancy are discussed: interference of the wake fields excited by a beam in adjacent components of the vacuum chamber, effect of computation mesh size, and effect of insufficient bandwidth of the computed impedance.

Authors:

Smaluk, Victor ^[1]

Brookhaven National Laboratory (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)

Publication Date:: 2018-04-21

Research Org.:: Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)

Sponsoring Org.:: USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:: 1426452

Report Number(s):: BNL-203335-2018-JAAM
Journal ID: ISSN 0168-9002; TRN: US1802284

Grant/Contract Number:: SC0012704

Resource Type:: Accepted Manuscript

Journal Name:: Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment

Additional Journal Information:: Journal Volume: 888; Journal Issue: C; Journal ID: ISSN 0168-9002

Publisher:: Elsevier

Country of Publication:: United States

Language:: English

Subject:: 43 PARTICLE ACCELERATORS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Cyclic accelerators and storage rings; Beams in particle accelerators; Beam dynamics; Collective effects and instabilities

Citation Formats


                    Smaluk, Victor. Impedance computations and beam-based measurements: A problem of discrepancy.  United States: N. p., 2018. 
Web.  doi:10.1016/j.nima.2018.01.047.

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                    Smaluk, Victor. Impedance computations and beam-based measurements: A problem of discrepancy.  United States.  https://doi.org/10.1016/j.nima.2018.01.047

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                    Smaluk, Victor. Sat .  
"Impedance computations and beam-based measurements: A problem of discrepancy".  United States.  https://doi.org/10.1016/j.nima.2018.01.047.  https://www.osti.gov/servlets/purl/1426452.

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@article{osti_1426452,

  title        = {Impedance computations and beam-based measurements: A problem of discrepancy},

  author       = {Smaluk, Victor},

  abstractNote = {High intensity of particle beams is crucial for high-performance operation of modern electron-positron storage rings, both colliders and light sources. The beam intensity is limited by the interaction of the beam with self-induced electromagnetic fields (wake fields) proportional to the vacuum chamber impedance. For a new accelerator project, the total broadband impedance is computed by element-wise wake-field simulations using computer codes. For a machine in operation, the impedance can be measured experimentally using beam-based techniques. In this article, a comparative analysis of impedance computations and beam-based measurements is presented for 15 electron-positron storage rings. The measured data and the predictions based on the computed impedance budgets show a significant discrepancy. For this article, three possible reasons for the discrepancy are discussed: interference of the wake fields excited by a beam in adjacent components of the vacuum chamber, effect of computation mesh size, and effect of insufficient bandwidth of the computed impedance.},

  doi          = {10.1016/j.nima.2018.01.047},

  journal      = {Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment},

  number       = C,

  volume       = 888,

  place        = {United States},

  year         = {2018},

  month        = {4}

}

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