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Teytelman, D.

Paper Title Page
MOPAS037 New Generation Digital Longitudinal Feedback System for Duke FEL and HIGS Facilities 518
  • Y. Kim, M. D. Busch, P. Wang, W. Wu, Y. K. Wu
    FEL/Duke University, Durham, North Carolina
  • J. Choi, I. S. Ko, I. S. Park
    PAL, Pohang, Kyungbuk
  • D. Teytelman
    Dimtel, Redwood City, California
  To increase intensity of the High Intensity Gamma-ray Source (HIGS) which is driven by the Duke storage ring FEL via Compton scattering, stored beam current should be increased. However, high-current multi-bunch operation in the Duke storage ring is limited by strong longitudinal coupled-bunch beam instabilities. To control those instabilities, we have been developing an active longitudinal feedback system which is based on the Integrated Gigasample Processor (iGP) through collaboration with Dimtel, Inc. and Pohang Accelerator Laboratory. In this paper, we report the present status of our longitudinal feedback system.  
MOPAS062 Analysis of the Longitudinal Low-order Mode Beam Dynamics in PEP-II Rings at High Current Beams 575
  • T. Mastorides, J. D. Fox, C. H. Rivetta, D. Teytelman, D. Van Winkle
    SLAC, Menlo Park, California
  Funding: Work supported by Department of Energy (USA) under contract # DE-AC02-76SF00515

PEP-II operations will increase the beam currents to 4A for LER and 2.2A for HER to achieve the final goal in luminosity. These magnitudes are challenging in part because they will push toward the limit the longitudinal low-order mode (LOM) beam stability due to beam loading. To analyze the behavior of both rings at high currents and understand the limits in the longitudinal feedback systems a simulation tool has been developed at SLAC. This tool is based on a reduced model of the longitudinal LOM dynamics of the beam interacting with the effective impedance presented by RF station. Simulations and measurements of the longitudinal beam behavior in both rings have been performed to understand the ultimate limit of the system. These studies have defined the impact of control loop parameters in the longitudinal beam dynamics, identified the poor performance of RF devices affecting the optimal performance of the RF stations and quantified the behavior of the longitudinal LOM beam dynamics. Results of sensitivity to parameter variations in the beam dynamics and limits in the maximum current that LER/HER can achieve based on the longitudinal beam stability are reported in this paper.

MOPAS067 Control and Measurements of Longitudinal Coupled-bunch Instabilities in the ATF Damping Ring 584
  • D. Teytelman, J. D. Fox
    SLAC, Menlo Park, California
  • W. X. Cheng, J. W. Flanagan, T. Naito, M. Tobiyama
    KEK, Ibaraki
  • A. Drago
    INFN/LNF, Frascati (Roma)
  Funding: Work supported by U. S. Department of Energy contract DE-AC02-76SF00515 and by the US-Japan collaboration in High Energy Physics

Damping ring at the Accelerator Test Facility (ATF) is a storage ring with 714 MHz RF frequency and harmonic number of 330. The ring is used in both single and multibunch regimes. In both cases significant longitudinal dipole motion has been observed in the ring. A prototype longitudinal feedback channel using a Gproto baseband processing channel and a set of horizontal striplines has been constructed for the machine. The prototype allowed both suppression of the longitudinal motion and studies of the motion sources. In this paper we present the results of these studies including measurements of steady-state oscillation amplitudes, eigenmodal patterns, and growth and damping rates. Using measured growth rates we estimate the driving impedances. We also present the effect of the longitudinal stabilization on the energy spread of the extracted beam as documented by a screen monitor.

TUPAN033 DAΦ NE Setup and Performances During the Second FINUDA Run 1457
  • C. Milardi, D. Alesini, M. E. Biagini, C. Biscari, R. Boni, M. Boscolo, B. Buonomo, A. Clozza, G. O. Delle Monache, T. Demma, E. Di Pasquale, G. Di Pirro, A. Drago, A. Gallo, A. Ghigo, S. Guiducci, M. Incurvati, P. Iorio, C. Ligi, F. Marcellini, C. Marchetti, G. Mazzitelli, L. Pellegrino, M. A. Preger, L. Quintieri, P. Raimondi, R. Ricci, U. Rotundo, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, S. Tomassini, C. Vaccarezza, M. Zobov
    INFN/LNF, Frascati (Roma)
  • J. D. Fox, D. Teytelman
    SLAC, Menlo Park, California
  • E. Levichev, S. A. Nikitin, P. A. Piminov, D. N. Shatilov
    BINP SB RAS, Novosibirsk
  Beam operations on DAΦNE restarted on October 2006 after a four months shut-down to remove the KLOE experimental detector and to install the FINUDA one. This period has been also used for maintenance and implementation of several upgrades. In the first two months of operation the peak and integrated luminosity already exceeds the values obtained during the first FINUDA run by 20%. The DAΦNE goal is to deliver 1 fb-1 integrated luminosity by the end of May 2007. The collider performances during the run are presented together with the improvements obtained in terms of ring nonlinearities and beam dynamics coming from several collider modifications.  
FRPMS077 High Current Effects in the PEP-II SLAC B-factory 4225
  • A. Novokhatski, S. A. Heifets, D. Teytelman
    SLAC, Menlo Park, California
  Funding: Work supported by US DOE contract DE-AC02-76SF00515.

Wake fields defining beam stability affect also the beam optics and beam properties in high current machines. We present observations and analysis of the optical effects in the PEP-II SLAC B-factory, which has the record in achievement of high electron and positron currents. We study the synchronous phase and the bunch length variation along the train of bunches, overall bunch lengthening and effects of the wakes on the tune and on the Twiss parameters. This analysis is being used in upgrades of PEP II and may be applied to future B-factories and damping rings for Linear Colliders.