Author: Macpherson, A.
Paper Title Page
TUPTEV010 Camera Placement in a Short Working Distance Optical Inspection System for RF Cavities 503
  • A. Macpherson, L.R. Buonocore, M. Di Castro, H. Gamper, A. Luthi
    CERN, Geneva, Switzerland
  Inspection of the RF surface of cavities for the purpose of detecting surface anomalies has been well established, and is typically based on long working distance optical systems using on-axis camera and mirror systems to scan the cavity surface. In order to improve the systematic inspection of the full RF surface of large area cavities, a novel short working distance inspection system is being developed at CERN. This new system is based on a mechatronic robotic system to position that camera at normal incidence close to the cavity surface. To accommodate working distance fluctuations, and to provide increased depth of field resolution, the short working distance camera is coupled with a liquid lens focusing system, providing a programmable focusing function. Details of inspection bench design and first results are reported, as well as details on camera positioning optimisation and the proximity detection surveillance for collision-free scanning of the full-cavity surface.  
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About • Received ※ 21 June 2021 — Revised ※ 25 August 2021 — Accepted ※ 18 November 2021 — Issue date ※ 30 January 2022
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Ferro-Electric Fast Reactive Tuners for SRF  
  • N.C. Shipman, M.R. Coly, F. Gerigk, A. Macpherson, N. Stapley, D. Valuch, W. Venturini Delsolaro
    CERN, Geneva, Switzerland
  • I. Ben-Zvi
    BNL, Upton, New York, USA
  • C.-J. Jing, A. Kanareykin
    Euclid TechLabs, Solon, Ohio, USA
  A Ferro-Electric Fast Reactive Tuner (FE-FRT) is a new type of tuner, utilising a novel ferro-electric material, which can change the frequency of an RF cavity on the sub-microsecond timescale and has the potential to reduce a cavity’s RF power requirements by an order of magnitude in some cases. During operation, power is continuously coupled out of the cavity, through the tuner, and reflected back into the cavity. By applying a high voltage across a ferro-electric within the tuner, the reactive load seen by the cavity is altered which causes a frequency shift in the cavity. The extremely fast response times of FE-FRTs make them especially suited to the correction of frequency variations caused by microphonics. New closed loop tuning measurements at CERN with a prototype FE-FRT and superconducting RF cavity have recently demonstrated excellent suppression of the cavity’s microphonics. The experimental set-up and the recent test results will be presented and the capabilities of this approach contrasted with more common systems, such as piezoelectric based tuners.  
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