Simulation of the APS Storage-ring Rf System
Simulation of the APS Storage-ring Rf System

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Published: 1997

Total Pages: 4

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A simulation model for the APS storage ring rf system has been developed that includes the effects of cavity impedances, longitudinal beam dynamics, and generator klystrons. The model predicts multiple-bunch longitudinal beam behavior and is used for feedback system design and stability analysis.

RF Characteristics of the APS Storage Ring Isolation Valve
RF Characteristics of the APS Storage Ring Isolation Valve

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Published: 1993

Total Pages: 4

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The rf impedance of the isolation valve of the APS storage ring system was measured by the wire method with a synthetic pulse technique. The coupling impedance as well as the energy loss of the sector valve with and without an rf liner or screen, and the flange gap of the various sizes was measured. There appear to be resonances at certain frequencies without an rf liner that might cause an unacceptably large coupling impedance. Data with various sizes of the flange gap show that good rf contact around any flange is necessary. The impedance due to intrusions into the beam chamber was also measured. The results are compared with the computer simulation from MAFIA.

Mechanical Design Upgrade of the APS Storage Ring Rf Cavity Tuner
Mechanical Design Upgrade of the APS Storage Ring Rf Cavity Tuner

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Published: 1997

Total Pages: 4

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The Advanced Photon Source (APS) storage ring (SR) rf system employs four banks of four spherical, single-cell resonant cavities. Each cavity is tuned by varying the cavity volume through insertion/retraction of a copper piston located at the circumference of the cavity and oriented perpendicular to the accelerator beam. During the commissioning of the APS SR, the tuners and cavity tuner ports were prone to extensive arcing and overheating. The existing tuners were modified to eliminate the problems, and two new, redesigned tuners were installed. In both cases marked improvements were obtained in the tuner mechanical performance. As measured by tuner piston and flange surface temperatures, tuner heating has been reduced by a factor of five in the new version. Redesign considerations discussed include tuner piston-to-housing alignment, tuner piston and housing materials and cooling configurations, and tuner piston sliding electrical contacts. The tuner redesign is also distinguished by a modular, more maintainable assembly.

Review of the APS SR RF Systems
Review of the APS SR RF Systems

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Published: 1998

Total Pages: 5

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The Advanced Photon Source (APS) is a 7-GeV full energy storage ring (SR) for generating synchrotron radiation with an injector. The storage ring cavities consist of four groups of four single cells powered by up to four 1-MW klystrons for up to 300-mA operation. A review of the operation of the rf system as well as rf-related beam dynamics is presented. This review includes rf power distribution, low-level feedback, control law, beam loading, beam instabilities, higher-order modes, and beam-induced multipactoring.

Higher-order Modes of Storage Ring Rf Cavities and Their Interaction with the Beam at the Advanced Photon Source (APS).
Higher-order Modes of Storage Ring Rf Cavities and Their Interaction with the Beam at the Advanced Photon Source (APS).

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Published: 1997

Total Pages: 6

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The higher-order modes (HOMs) of APS storage ring (SR) rf cavities and waveguides were measured under various operating conditions. The HOMs of the 352-MHz rf cavity can be one of the major contributors to the coupled bunch (CB) instability. The distribution of HOMs under various conditions of beam current, cavity temperature, cavity tuning, single-bunch and multi-bunch operation, and fill patterns, are presented. The HOMs' shunt impedance of the loaded cavities were also measured. The effect of stagger tuning of the 16 cavities and their waveguide system is compared, and the HOM dampers are examined.

An Overview of the APS 352-MHz Rf Systems
An Overview of the APS 352-MHz Rf Systems

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Published: 1997

Total Pages: 4

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The Advanced Photon Source (APS) is a 7-GeV full energy positron storage ring for generating synchrotron radiation with an injector. The booster synchrotron rf system consists o a single 1-MW klystron which drives four five-cell cavities at 352 MHz. The storage ring cavities consist of four groups of four single cells powered by two 1-MW klystrons for 100-mA operation. An overview of the operation of the APS 352-MHz rf systems is presented.