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Walters, D. R.

Paper Title Page
MOPAN115 Aluminum Coating in the Undulator Vacuum Chamber for the LINAC Coherence Light Source 437
  • D. R. Walters
    ANL, Argonne, Illinois
  Funding: Work supported by DOE under contract Nos. DE-AC02-06CH11357 and DE-AC03-76SF00515.

A prototype vacuum chamber is under development at the Advanced Photon Source for use in the Linac Coherent Light Source at Stanford Linear Accelerator Center. The chamber will be fabricated from the austenite stainless steels. The chamber requires a continuous aluminum coating on the inner surface in order to reduce the wakefield losses to a level within the resistivity budget. The method being presented here is unique in that it can be applied to a fully fabricated chamber 5 mm high, 11.5 mm wide, and 3460 mm long. In existing methods the chamber aperture has been much larger than is used here. This paper describes a method applicable for these smaller cross sections. This process uses a pair of small electrodes, centered in the aperture, where they are attached to a high frequency AC power supply. In this configuration each electrode is connected to the opposite polarity of the other. The chamber cavity is filled with argon gas to facilitate the formation of a glow discharge causing the aluminum electrodes to sputter onto the chamber walls. This paper presents the laboratory test results from small samples up to the full-sized assemblies.

FRPMN111 Design and Performance of the LCLS Cavity BPM System 4366
  • R. M. Lill, L. H. Morrison, W. E. Norum, N. Sereno, G. J. Waldschmidt, D. R. Walters
    ANL, Argonne, Illinois
  • S. Smith, T. Straumann
    SLAC, Menlo Park, California
  Funding: Work supported by U. S. Department of Energy under Contract Nos. DE-AC02-06CH11357 and DE-AC03-76SF00515

In this paper we present the design of the beam position monitor (BPM) system for the LCLS undulator, which features a high resolution X-band cavity BPM. Each BPM has a TM010 monopole reference cavity and a TM110 dipole cavity designed to operate at a center frequency of 11.384 GHz. The signal processing electronics features a low-noise single-stage three-channel heterodyne receiver that has selectable gain and a phase locking local oscillator. We will discuss the system specifications, design, and prototype test results.