Multi-Bunch Longitudinal Dynamics and Diagnostics via a Digital Feedback System at PEP-II, DAFNE, ALS and SPEAR

Fox, John D

doi:10.2172/10206

Title: Multi-Bunch Longitudinal Dynamics and Diagnostics via a Digital Feedback System at PEP-II, DAFNE, ALS and SPEAR

Full Record
Other Related Research

Abstract

A bunch-by-bunch longitudinal feedback system based on a programmable DSP architecture is used to study coupled-bunch motion and its sources. Experimental results are presented from PEP-II, DA{Phi}NE, ALS and SPEAR to highlight the operational experience from 4 installations, plus show novel accelerator diagnostics possible with the digital processing system. Modal growth and damping rates are measured via short (20 ms) transient recordings for unstable and stable coupled-bunch modes. Data from steady-state measurements are used to identify unstable modes and noise-driven beam motion. A novel impedance measurement technique is presented which reveals the longitudinal impedance as a function of frequency. This technique uses the measured synchronous phase and charge of every bucket to calculate the impedance seen by the beam at revolution harmonics.

Authors:: Fox, John D

Publication Date:: Mon Apr 19 00:00:00 EDT 1999

Research Org.:: SLAC National Accelerator Lab., Menlo Park, CA (United States)

Sponsoring Org.:: USDOE Office of Energy Research (ER) (US)

OSTI Identifier:: 10206

Report Number(s):: SLAC-PUB-8128
TRN: US0103383

DOE Contract Number:: AC03-76SF00515

Resource Type:: Technical Report

Resource Relation:: Other Information: PBD: 19 Apr 1999

Country of Publication:: United States

Language:: English

Subject:: 43 PARTICLE ACCELERATORS; ACCELERATORS; DAMPING; FEEDBACK; HARMONICS; IMPEDANCE; SPEAR; PEP STORAGE RINGS; ADVANCED LIGHT SOURCE; BEAM BUNCHING

Citation Formats


                    Fox, John D. Multi-Bunch Longitudinal Dynamics and Diagnostics via a Digital Feedback System at PEP-II, DAFNE, ALS and SPEAR.  United States: N. p., 1999. 
        Web.  doi:10.2172/10206.

Copy to clipboard


                    Fox, John D. Multi-Bunch Longitudinal Dynamics and Diagnostics via a Digital Feedback System at PEP-II, DAFNE, ALS and SPEAR.  United States.  https://doi.org/10.2172/10206

Copy to clipboard


                    Fox, John D. 1999.  
        "Multi-Bunch Longitudinal Dynamics and Diagnostics via a Digital Feedback System at PEP-II, DAFNE, ALS and SPEAR".  United States.  https://doi.org/10.2172/10206.  https://www.osti.gov/servlets/purl/10206.

Copy to clipboard


                    
@article{osti_10206,

  title        = {Multi-Bunch Longitudinal Dynamics and Diagnostics via a Digital Feedback System at PEP-II, DAFNE, ALS and SPEAR},

  author       = {Fox, John D},

  abstractNote = {A bunch-by-bunch longitudinal feedback system based on a programmable DSP architecture is used to study coupled-bunch motion and its sources. Experimental results are presented from PEP-II, DA{Phi}NE, ALS and SPEAR to highlight the operational experience from 4 installations, plus show novel accelerator diagnostics possible with the digital processing system. Modal growth and damping rates are measured via short (20 ms) transient recordings for unstable and stable coupled-bunch modes. Data from steady-state measurements are used to identify unstable modes and noise-driven beam motion. A novel impedance measurement technique is presented which reveals the longitudinal impedance as a function of frequency. This technique uses the measured synchronous phase and charge of every bucket to calculate the impedance seen by the beam at revolution harmonics.},

  doi          = {10.2172/10206},

  url          = {https://www.osti.gov/biblio/10206},
  journal      = {},
number       = ,

  volume       = ,

  place        = {United States},

  year         = {Mon Apr 19 00:00:00 EDT 1999},

  month        = {Mon Apr 19 00:00:00 EDT 1999}

}

Copy to clipboard

Technical Report:

View Technical Report

https://doi.org/10.2172/10206

Save / Share:

Export Metadata

Save to My Library

Similar records in OSTI.GOV collections:

Multi-Bunch Instability Diagnostics via Digital Feedback Systems at PEP-II, DAFNE, ALS and SPEAR

Technical Report Fox, John

Longitudinal feedback systems based on a common programmable DSP architecture have been commissioned at 4 laboratories. In addition to longitudinal feedback and beam diagnostics these flexible systems have been programmed to provide diagnostics for transverse motion. The diagnostic functions are based on transient domain techniques which record the response of every bunch while the feedback system manipulates the beam. Operational experience from 4 installations is illustrated via experimental results from PEP-II, DAFNE, ALS and SPEAR. Modal growth and damping rates for transverse and longitudinal planes are measured via short (20 ms) transient excitations for unstable and stable coupled-bunch modes. Datamore »« less
https://doi.org/10.2172/10064

Full Text Available
Observation, control, and modal analysis of longitudinal coupled-bunch instabilities in the ALS via a digital feedback system

Journal Article Fox, J; Claus, R; Hindi, H; ... - AIP Conference Proceedings

The operation of a longitudinal multibunch damping system using digital signal processing (DSP) techniques is shown via measurements from the Lawrence Berkeley Laboratory (LBL) Advanced Light Source (ALS). The feedback system (developed for use by PEP-II, ALS, and DA{Phi}NE) uses a parallel array of signal processors to implement a bunch-by-bunch feedback system for sampling rates up to 500 MHz. The programmable DSP system allows feedback control as well as accelerator diagnostics. A diagnostic technique is illustrated which uses the DSP system to excite and then damp the beam. The resulting 12-ms time domain transient is Fourier analyzed to provide themore »« less
https://doi.org/10.1063/1.52278
Observation, control and modal analysis of longitudinal coupled-bunch instabilities in the ALS via a digital feedback system

Conference Fox, J; Claus, R; Hindi, H

The operation of a longitudinal multi-bunch damping system using digital signal processing techniques is shown via measurements from the LBL Advanced Light Source. The feedback system (developed for use by PEP-II, ALS and DA{Phi}NE) uses a parallel array of signal processors to implement a bunch by bunch feedback system for sampling rates up to 500 MHz. The programmable DSP system allows feedback control as well as accelerator diagnostics. A diagnostic technique is illustrated which uses the DSP system to excite and then damp the beam. The resulting 12 ms time domain transient is Fourier analyzed to provide the simultaneous measurementmore »« less
Full Text Available
New diagnostics and cures for coupled-bunch instabilities

Technical Report Prabhakar, S

Electromagnetic interaction between a charged particle beam and its surroundings causes collective instabilities, which must be controlled if the new light sources and colliders are to meet their design goals. Control requires a combination of passive damping and fast active feedback on an unprecedented technological scale. Efficient instability diagnosis techniques are also needed for machines with large numbers of bunches. This thesis describes new methods of measuring and analyzing coupled-bunch instabilities in circular accelerators, and demonstrates the existence of a new cure. A new technique is demonstrated for simultaneous measurement of growth rates, damping rates and coherent tune shifts ofmore »« less
https://doi.org/10.2172/753308

Full Text Available
New Diagnostics and Cures for Coupled-Bunch Instabilities

Technical Report Prabhakar, Shyam

Electromagnetic interaction between a charged particle beam and its surrounding causes collective instabilities, which must be controlled if the new light sources and colliders are to meet their design goals. Control requires a combination of passive damping and fast active feedback on an unprecedented technological scale. Efficient instability diagnosis techniques are also needed for machines with large numbers of bunches. This thesis describes new methods of measuring and analyzing coupled-bunch instabilities in circular accelerators, and demonstrates the existence of a new cure. A new technique is demonstrated for simultaneous measurement of growth rates, damping rates and coherent tune shifts ofmore »« less
https://doi.org/10.2172/1454228

Full Text Available

Similar Records