Design and vertical tests of double-quarter wave cavity prototypes for the high-luminosity LHC crab cavity system

Verdú-Andrés, S. and Burt, Graeme Campbell and Shipman, Nicholas (2018) Design and vertical tests of double-quarter wave cavity prototypes for the high-luminosity LHC crab cavity system. Physical Review Accelerators and Beams, 21 (8). ISSN 2469-9888

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Abstract

Crab crossing is essential for high-luminosity colliders. The high-luminosity Large Hadron Collider (HL-LHC) will equip one of its interaction points (IP1) with double-quarter wave (DQW) crab cavities. A DQW cavity is a new generation of deflecting rf cavities that stands out for its compactness and broad frequency separation between fundamental and first high-order modes. The deflecting kick is provided by its fundamental mode. Each HL-LHC DQW cavity shall provide a nominal deflecting voltage of 3.4 MV, although up to 5.0 MV may be required. A proof-of-principle (POP) DQW cavity was limited by quench at 4.6 MV. This paper describes a new, highly optimized cavity, designated the DQW SPS series, which satisfies dimensional, cryogenic, manufacturing, and impedance requirements for beam tests at the Super Proton Synchrotron (SPS) and operation in the LHC. Two prototypes of this DQW SPS series were fabricated by U.S. industry and cold tested after following a conventional superconducting radio-frequency surface treatment. Both units outperformed the POP cavity, reaching a deflecting voltage of 5.3–5.9 MV. This voltage—the highest reached by a DQW cavity—is well beyond the nominal voltage of 3.4 MV and may even operate at the ultimate voltage of 5.0 MV with a sufficient margin. This paper covers fabrication, surface preparation, and cryogenic rf test results and implications.

Item Type:
Journal Article
Journal or Publication Title:
Physical Review Accelerators and Beams
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
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ID Code:
127178
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Deposited On:
03 Sep 2018 12:02
Refereed?:
Yes
Published?:
Published
Last Modified:
20 Sep 2020 05:01