CERN Accelerating science

Article
Report number	arXiv:1805.08123 ; FERMILAB-PUB-18-207-TD
Title	Design and Vertical Tests of SPS-series Double-Quarter Wave (DQW) Cavity Prototypes for the HL-LHC Crab Cavity System Design and vertical tests of double-quarter wave cavity prototypes for the high-luminosity LHC crab cavity system
Author(s)	Verdú-Andrés, S. (Brookhaven Natl. Lab.) ; Artoos, K. (CERN) ; Belomestnykh, S. (Brookhaven Natl. Lab. ; Fermilab ; Stony Brook U.) ; Ben-Zvi, I. (Brookhaven Natl. Lab. ; Stony Brook U.) ; Boulware, C. (Unlisted, US, MI) ; Burt, G. (Lancaster U. (main) ; Cockcroft Inst. Accel. Sci. Tech.) ; Calaga, R. (CERN) ; Capatina, O. (CERN) ; Carra, F. (CERN) ; Castilla, A. (CERN) ; Clemens, W. (Jefferson Lab) ; Grimm, T. (Unlisted, US, MI) ; Kuder, N. (CERN) ; Leuxe, R. (CERN) ; Li, Z. (SLAC) ; McEwen, E.A. (Jefferson Lab) ; Park, H. (Jefferson Lab) ; Powers, T. (Jefferson Lab) ; Ratti, A. (SLAC ; LBNL, Berkeley) ; Shipman, N. (Lancaster U. (main) ; Cockcroft Inst. Accel. Sci. Tech.) ; Skaritka, J. (Brookhaven Natl. Lab.) ; Wu, Q. (Brookhaven Natl. Lab.) ; Xiao, B.P. (Brookhaven Natl. Lab.) ; Yancey, J. (Unlisted, US, MI) ; Zanoni, C. (CERN)
Publication	2018-08-13
Imprint	2018-05-21
Number of pages	3
In:	Phys. Rev. Accel. Beams 21 (2018) 082002
DOI	10.1103/PhysRevAccelBeams.21.082002
Subject category	physics.acc-ph ; Accelerators and Storage Rings
Accelerator/Facility, Experiment	CERN SPS CERN HL-LHC
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 DQW SPS-series, which satisfies dimensional, cryogenic, manufacturing and impedance requirements for beam tests at SPS and operation in LHC. Two prototypes of this DQW SPS-series were fabricated by US industry and cold tested after following conventional SRF 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 5.0MVwith sufficient margin. This paper covers fabrication, surface preparation and cryogenic RF test results and implications.
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