Room temperature RF
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MOPORI20 Fabrication, Field Measurement, and Testing of a Compact RF Deflecting Cavity for ELBE 271
  • T.G. Hallilingaiah, P. Michel, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • A. Arnold, S. Köppen, P. Michel
    HZDR, Dresden, Germany
  • U. van Rienen
    University of Rostock, Rostock, Germany
  A transverse deflecting cavity is being developed for the electron linac ELBE to separate the bunches into two or more beamlines so that multiple user experiments can be carried out simultaneously. A normal conducting double quarter-wave cavity has been designed to deliver a transverse kick of 300 kV when driven by an 800 W solid-state amplifier at 273 MHz. The main challenges in fabrication were machining the complex cavity parts with high precision, pre-tuning the cavity frequency, and the final vacuum brazing within the tolerances, which are described in this paper. The reason for a low intrinsic quality factor measured during the low power test was investigated, and suitable steps were taken to improve the quality factor. The cavity field profiles obtained from the bead-pull measurement matched the simulation results. Further, the cavity was driven up to 1 kW using a modified pick-up antenna, and eventually, vacuum conditioning of the cavity was accomplished. The cavity fulfils the design requirements and is ready for beam tests.  
poster icon Poster MOPORI20 [4.325 MB]  
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About • Received ※ 14 August 2022 — Revised ※ 15 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 07 September 2022
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MOPORI22 High-Power Test of an APF IH-DTL Prototype for the Muon Linac 275
SUPCRI07   use link to see paper's listing under its alternate paper code  
  • Y. Nakazawa, H. Iinuma
    Ibaraki University, Ibaraki, Japan
  • E. Cicek, H. Ego, K. Futatsukawa, N. Kawamura, T. Mibe, S. Mizobata, N. Saito, M. Yoshida
    KEK, Ibaraki, Japan
  • N. Hayashizaki
    Research Laboratory for Nuclear Research, Tokyo Institute of Technology, Tokyo, Japan
  • Y. Iwata
    NIRS, Chiba-shi, Japan
  • R. Kitamura, Y. Kondo, T. Morishita
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • M. Otani
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • Y. Sue, K. Sumi, M. Yotsuzuka
    Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
  • Y. Takeuchi
    Kyushu University, Fukuoka, Japan
  • T. Yamazaki
    KEK, Tokai Branch, Tokai, Naka, Ibaraki, Japan
  • H.Y. Yasuda
    University of Tokyo, Tokyo, Japan
  A muon linac is under development for a new muon g-2/EDM experiment at J-PARC. The muons are cooled to about room temperature and then re-accelerated to 212 MeV by four linear accelerators to produce a low-emittance muon beam. In the low-beta section, a short-range acceleration cavity with high efficiency needs to be developed to suppress the decay of muons. We propose a 324 MHz inter-digital H-mode drift-tube linac (IH-DTL) with high acceleration efficiency. The cavity can be downsized by introducing the alternating phase focusing (APF) method that provides transverse focusing only with an E-field. We have developed a prototype cavity that accelerates muons up to 1.3 MeV to demonstrate the principle. In this paper, the result of the high power test of the APF IH-DTL prototype is reported.  
poster icon Poster MOPORI22 [10.978 MB]  
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About • Received ※ 13 August 2022 — Revised ※ 16 August 2022 — Accepted ※ 28 August 2022 — Issue date ※ 01 September 2022
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MOPORI23 High-Power Testing Results of X-Band RF-Window and 45 Degrees Spiral Load 279
  • M. Boronat, H. Bursali, N. Catalán Lasheras, A. Grudiev, G. McMonagle, I. Syratchev
    CERN, Meyrin, Switzerland
  The X-Band test facilities at CERN have been running for some years now qualifying CLIC structure prototypes but also developing and testing high power general-purpose X-Band components, used in a wide range of applications. Driven by operational needs, several components have been redesigned and tested aiming to optimize the reliability and the compactness of the full system and therefore enhancing the accessibility of this technology inside and outside CERN. To this extent, a new high-power RF-window has been designed and tested aiming to avoid unnecessary venting of high-power sections already conditioned, easing the interventions, and protecting the klystrons. A new spiral load prototype has also been designed, built, and tested, optimizing the compactness, and improving the fabrication process. In these pages, the design and manufacturing for each component will be shortly described, along with the last results on the high-power testing.  
poster icon Poster MOPORI23 [2.275 MB]  
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About • Received ※ 24 August 2022 — Revised ※ 29 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 31 August 2022
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MOPORI24 Monte Carlo Model of High-Voltage Conditioning and Operation 283
  • W.L. Millar, W. Wuensch
    CERN, Meyrin, Switzerland
  • G. Burt
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  To synthesise the experimental results and theory pertaining to high-field phenomena, a model has been developed to simulate the conditioning and operation of high-field systems. By using a mesh-based method, the high-field conditioning of any arbitrary geometry and surface electric field distribution may be simulated for both RF and DC devices. Several phenomena observed in previous high-field tests such as the probabilistic behaviour of vacuum arcs and the inhomogeneous distribution of arc locations are described by this approach.  
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About • Received ※ 20 August 2022 — Revised ※ 22 August 2022 — Accepted ※ 28 August 2022 — Issue date ※ 15 September 2022
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MOPORI26 Limits on Standing Wave Cavity Performance Due to Thermal Effects 287
SUPCRI02   use link to see paper's listing under its alternate paper code  
  • S.J. Smith, G. Burt
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  After an RF cavity has been designed, a thermal analysis is typically performed to assess the effects of RF heating on the operating frequency and field flatness. A multi-physics approach (coupled electromagnetic, thermal, and mechanical) is normally employed, sometimes combined with computational fluid dynamics (CFD) simulations to incorporate flowing water, which is used for cooling in normal conducting structures. Performing a CFD analysis can add significant time to the design process because of the long and complex simulations and instead, approximations of the heat transfer coefficients and inlet/outlet water temperature rises are made and used directly in the multi-physics analysis. In this work, we first explore the limits of these approximations, identifying when they apply and how accurate they are. We then investigate different pipe geometries and water flow rates to find the thermal limits from RF heating on cavity performance.  
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About • Received ※ 17 August 2022 — Revised ※ 20 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 15 September 2022
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