Download or read book INITIAL COMMISSIONING RESULTS FROM THE PEP II TRANSVERSE COUPLED BUNCH FEEDBACK SYSTEMS written by and published by . This book was released on 2003 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: Initial commissioning results from the PEP-II transverse coupled-bunch feedback systems are discussed. In particular, the performance of key hardware and coupled-bunch damping results are described in some detail. Beam dynamics related measurements presented include beam transfer functions and selected modal growth and damping rates.
Download or read book EPAC 98 written by S. Myers and published by Institute of Physics Publishing (GB). This book was released on 1998 with total page 872 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Commissioning Experience from PEP II HER Longitudinal Feedback written by and published by . This book was released on 1998 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The DSP-based bunch-by-bunch feedback system installed in the PEP-II HER has been used to damp HOM-induced instabilities at beam currents up to 6-5 mA during commissioning. Beam pseudospectra calculated from feedback system data indicate the presence of coupled bunch modes that coincide with the 0-M-2 cavity HOM. Bunch current and synchronous phase measurements are also extracted from the data. These measurements reveal the impedance seen by the beam at revolution harmonics. The impedance peak at 3*frev indicates incorrect parking of the idle cavities, and explains the observed instability of mode 3. Bunch synchrotron tunes are calculated from lorentzian fits to the data. Bunch-to-bunch time variation due to the cavity transient is shown to be large enough to result in Landau damping of coupled bunch modes.
Download or read book Transverse Feedback Systems for the PEP II B factory written by and published by . This book was released on 1995 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Growth rates of coherent beam oscillations are faster than the natural damping mechanisms for the parameters of the PEP-II B-factory storage rings at nominal currents, even with damping of cavity higher order modes (HOM's). With 165 8 bunches separated by 4.2 ns, and a large current of up to 3A (2.14 A nominal in the low energy ring), many coupled-bunch modes are excited by the resistive wall impedance and cavity higher order mode impedance. Fastest growth times of transverse rigid-bunch modes of approximately 300 ps are expected, two orders of magnitude faster than the radiation damping time. We will provide broadband, bunch-by-bunch feedback to suppress this coherent motion of the beam. Experience gained with a prototype system, installed and successfully operating at the LBNL Advanced Light Source (ALS), has been used extensively in developing the design of the PEP-II systems.
Download or read book Proceedings written by and published by . This book was released on 1995 with total page 788 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the 1995 Particle Accelerator Conference written by and published by . This book was released on 1996 with total page 794 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Collective Phenomena in Synchrotron Radiation Sources written by Shaukat Khan and published by Springer Science & Business Media. This book was released on 2007-01-19 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book helps dispel the notion that collective phenomena, which have become increasingly important in modern storage rings, are an obscure and inaccessible topic. The book serves as a valuable guide on how to improve synchrotrons and other storage rings. Despite an emphasis on synchrotron light sources, the basic concepts presented here are valid for other facilities as well.
Download or read book Proceedings of the 1999 Particle Accelerator Conference written by and published by . This book was released on 1999 with total page 760 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1994-11 with total page 486 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurements and Analysis of Longitudinal HOM Driven Coupled Bunch Modes in PEP II Rings written by and published by . This book was released on 2008 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The growth rates of the longitudinal higher-order impedance-driven beam modes have greatly increased since the initial PEP-II design and commissioning. This increase is attributed to the addition of 6 1.2MW RF stations with 8 accelerating cavities in the HER and 2 1.2MW RF stations with 4 accelerating cavities in the LER, which allowed operations at twice the design current and almost four times the luminosity. As a result, the damping requirements for the longitudinal feedback have greatly increased since the design, and the feedback filters and control schemes have evolved during PEP-II operations. In this paper, growth and damping rate data for the higher-order mode (HOM) driven coupled-bunch modes are presented from various PEP-II runs and are compared with historical estimates during commissioning. The effect of noise in the feedback processing channel is also studied. Both the stability and performance limits of the system are analyzed.
Download or read book Measurements of Transverse Coupled Bunch Instabilities in PEP II written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: At the design currents the PEP-II High and Low Energy Rings operate above the coupled-bunch instability thresholds in horizontal and vertical planes. Both machines have used analog bunch-by-bunch feedback systems to stabilize the beams since commissioning. Here we present a measurement technique that uses the capabilities of the PEP-II programmable digital longitudinal feedback system to provide transient diagnostics in X or Y directions. This technique allows one to measure instability growth or damping rates as well as oscillation frequencies in both open-loop and closed-loop conditions. Based on these measurements the configuration of the relevant transverse feedback channel can be optimized. The technique will be illustrated with instability measurements and feedback optimization examples. Comparisons of the measured modal patterns and growth rates to the theoretical predictions will be presented.
Download or read book Epac 96 written by S. Myers and published by CRC Press. This book was released on 1996-01-01 with total page 1054 pages. Available in PDF, EPUB and Kindle. Book excerpt: EPAC 96; Proceedings of the Fifth European Particle Accelerator Conference, Sitges (Barcelona), 10 to 14 June 1996, Three Volume Set, also available on a CD-ROM, provides a comprehensive overview of research, technology, and special applications in the field of accelerators. It serves as a source for novel ideas and familiarizes researchers with advanced concepts.
Download or read book Study of Coupled bunch Collective Effects in the PEP II B Factory written by and published by . This book was released on 1993 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present an overview of the calculated longitudinal and transverse coupled-bunch (CB) growth using the measured RF cavity higher order mode impedance and estimated resistive wall (RW) impedance for the proposed PEP-II B-Factory, a dual-ring electron-positron collider. We also describe a visual method of representing the effective beam impedance and corresponding growth rates which is especially useful for understanding the dependence of growth rate on higher order mode frequency and Q, spread of HOM frequencies between cells, and for determining the requirements of the CB feedback systems.
Download or read book Measurements of a Fast Vertical Instability in the PEP II HER written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The HER beam current was limited to tens of mA by a strong vertical coupled bunch instability during PEP-II commissioning in July '98. In the absence of transverse feedback, vertical oscillations were seen to be unstable at currents as low as 5 mA. The instability has been observed by using the HER longitudinal feedback electronics to digitize and store the vertical beam signal used for transverse feedback. This note presents measurements of modal growth and damping rates at two different vacuum pressures for 291 bunch uniform fills as well as 100 and 150 bunch train measurements. In some cases the unstable modes maintain a constant residual amplitude when feedback is on, and exhibit nonlinear behavior when feedback is switched off. Knowledge of the shape, speed and spectral location of the modal transients should help in diagnosing the cause of instability.
Download or read book New Diagnostics and Cures for Coupled bunch Instabilities written by Shyam Prabhakar and published by . This book was released on 2000 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Feedback Systems for PEP II written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Feedback systems have been commissioned for the PEP-II B factory to control orbit drifts from thermal and other transients, and to optimize the transverse overlap of the stored beams at the interaction point. BPM-based feedback loops correct the orbit at several points around both the low- and the high-energy ring. The beams are kept centered in collision by an optimization feedback that dithers the transverse position of one of the beams at the interaction point to maximize the readout of a radiative-Bhabha luminosity monitor. Luminosity-optimization dithering is also used to stabilize the relative vertical angle of the two beams, and to keep the positron beam aimed at the luminosity monitor. The current implementation acts on the beams at a rate of up to 2 Hz, and can compensate for changes within 10 seconds or less. This paper outlines the implementation of the feedback loops, and highlights the main improvements inspired by the first year of physics running at PEP-II.
Download or read book European Particle Accelerator Conference Epac 94 In 3 Volumes written by Christine Petit-jean-genaz and published by World Scientific. This book was released on 1994-11-26 with total page 2968 pages. Available in PDF, EPUB and Kindle. Book excerpt: These proceedings aim to provide a comprehensive overview of research, technology and applications in the field of accelerators. Contributions from the entire field of accelerators are presented, including low and high energy machines, and medical and industrial accelerators.
