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Effect of the Coupled-bunch Modes on the Longitudinal Feedback System

Description: The Pedersen analysis [1, 2] of the low-level rf feedback system assumes that all bunches oscillate in phase what corresponds to the lowest coupled bunch mode. This analysis is extended here to take into account all other coupled-bunch modes what might be important for the strongly detuned cavities in large storage rings such as PEP-II.
Date: November 30, 2006
Creator: Heifets, S. & Teytelman, D.
Partner: UNT Libraries Government Documents Department

Non Linear Beam Dynamics Studies at SPEAR

Description: The frequency map analysis of a Hamiltonian system recently introduced to accelerators physics in combination with turn-by-turn phase space measurements opens new experimental opportunities for studying non linear dynamic in storage rings. In this paper we report on the experimental program at SPEAR having the goal of measuring the frequency map of the machine. In this paper we discuss the accuracy of the instantaneous tune extraction from experimental data and demonstrate the possibility of the frequency map measurement. The instantaneous tune extraction technique can be applied to experimental tracking data with reasonable accuracy. Frequency map can be experimentally determined using the existing turn-by-turn phase space measurement techniques and NAFF instantaneous tune extraction.
Date: September 12, 2011
Creator: Terebilo, A.; Pellegrini, C.; /UCLA; Cornacchia, M.; Corbett, J.; Martin, D. et al.
Partner: UNT Libraries Government Documents Department

Beam Position Monitor System for PEP II

Description: We describe the beam position monitor system built for PEP-II, the B-factory at SLAC. The system reports beam position for bunches of between 5 x 10{sup 8} and 8 x 10{sup 10} electron charges, either singly or as continuous streams of bunches every 4.2 ns. Resolution at full charge is to be better than 10 microns in a single turn. Higher resolution is available via on-board multi-turn averaging. The position signal is processed in a 20 MHz bandwidth around 952 MHz. This bandwidth, rather broader than that typical of RF position monitors, allows good resolution for low charge single bunches. Additional novel features include stringent control of return losses in order to minimize cross-talk between nearby bunches which may contain very different charges. The digitizing electronics is multiplexed between the two PEP-II storage rings. Design, construction, and installation experience, as well as first results with beam are presented.
Date: September 12, 2011
Creator: Smith, Stephen R.; Aiello, G.Roberto; Hendrickson, Linda J.; Johnson, Ronald G.; Mills, Mark R.; Olsen, Jeff J. et al.
Partner: UNT Libraries Government Documents Department

Study for ILC Damping Ring at KEKB

Description: ILC damping ring consists of very low emittance electron and positron storage rings. It is necessary for ILC damping ring to study electron cloud effects in such low emittance positron ring. We propose a low emittance operation of KEKB to study the effects.
Date: November 4, 2011
Creator: Flanagan, J.W.; Fukuma, H.; Kanazawa, K.I.; Koiso, H.; Masuzawa, M.; Ohmi, Kazuhito et al.
Partner: UNT Libraries Government Documents Department

Recording PEP2 Ring Beam Losses at SLAC

Description: The PEP2 (e+)(e-) storage rings contain many complex interrelated systems. When the beam aborts, examining a record of the orbit from the time just before the abort can help identify the root cause. At the Stanford Linear Accelerator Center (SLAC) a system has been developed to continuously record beam orbits from Beam Position Monitors (BPMS) into a circular buffer. When the beam is aborted the buffers are frozen and their contents are stored for later analysis. BPM orbits are saved on a turn by turn basis for 2800 turns in both the high energy ring (HER) and the low energy ring (LER). Each BPM Processor (BPMP) can either monitor the HER or the LER, but not both as the readout of the two rings is multiplexed into a single readout channel. Tools exist as part of the SLAC Control Program (SCP) to collect, display, and save the data. A physicist or operator can choose a few BPMS in which to view all 2800 turns to identify the turn in which the beam went awry; then ask for that specific orbit from all of the BPMS in the storage ring to determine the root cause of the abort.
Date: September 30, 2005
Creator: Zelazny, M.; Gromme, T.; Himel, T.; Hendrickson, L.; Krauter, K. & /SLAC
Partner: UNT Libraries Government Documents Department