Field configuration of beam excited modes in the Advanced Photon Source (APS) storage ring waveguides

Technical Report · Tue May 31 00:00:00 EDT 1994

DOI:https://doi.org/10.2172/10165937· OSTI ID:10165937

Brauer, S. O. ^[1]; Kustom, R. L. ^[1]; Uslenghi, P. L.E. ^[2]

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1. Argonne National Lab., IL (United States). Advanced Photon Source
2. Univ. of Illinois, Chicago, IL (United States). Dept. of Electrical Engineering and Computer Science

Argonne National Laboratory (ANL) is in the process of building a positron accelerator and storage ring, the Advanced Photo source (APS). The RF system for the APS storage ring uses 16 cylindrical TM010-like, reentrant cavities operating at 351.93 MHz to resupply energy lost by the beam due to synchrotron radiation. The stored beam will have approximately 60 bunches, 5 mA per bunch, for a total beam current of 300 mA. Calculations of the threshold current for coupled-bench instabilities in the storage ring have indicated that several beam-induced higher-order modes (HOMs) will reduce the threshold for beam stability and therefore should be damped. Previous data taken using a pillbox cavity showed that it is likely that some of these modes couple, through the coupling loop, from the storage ring cavity into the waveguide. This study investigates the electric and magnetic field configuration of each HOM present in the waveguide. A pillbox and a prototype storage ring cavity, together with various WR2300 waveguide components, are used to obtain the measurements needed for the determination of the mode configuration of the HOMs at the frequencies of interest. To avoid the development of beam instabilities due to the existence of these HOMs in the rf cavity, damping of the modes will be required. The HOMs present in the rf cavity coupling into the loop coupler and traveling through the coupler into the waveguide, may allow damping of some of the HOMs by insertion of dampers into the waveguide adjacent to each cavity.

• Research Organization: Argonne National Lab., IL (United States). Advanced Photon Source Accelerator Systems Div.
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 10165937
• Report Number(s): ANL/APS/CP-83263; CONF-940531-2; ON: DE94015096; TRN: 94:014634
• Resource Relation: Conference: International symposium on electromagnetic environments and consequences, Bordeaux (France), 30 May - 3 Jun 1994; Other Information: PBD: [1994]
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
ADVANCED PHOTON SOURCE
OSCILLATION MODES
WAVEGUIDES
BEAM CURRENTS
RF SYSTEMS
ENERGY LOSSES
DAMPING
ELECTRIC FIELDS
MAGNETIC FIELDS
STABILITY
MAGNETIC FIELD CONFIGURATIONS
EXPERIMENTAL DATA
ANTENNAS
IMPEDANCE
430400
430200
STORAGE RINGS
BEAM DYNAMICS, FIELD CALCULATIONS, AND ION OPTICS