TY - JOUR
T1 - Cryogenic surface resistance of copper
T2 - Investigation of the impact of surface treatments for secondary electron yield reduction
AU - Calatroni, Sergio
AU - Arzeo, Marco
AU - Aull, Sarah
AU - Himmerlich, Marcel
AU - Costa Pinto, Pedro
AU - Vollenberg, Wilhelmus
AU - Di Girolamo, Beniamino
AU - Cruikshank, Paul
AU - Chiggiato, Paolo
AU - Bajek, David
AU - Wackerow, Stefan
AU - Abdolvand, Amin
N1 - Funding Information:
The authors acknowledge the contribution of Veronica Del Pozo Romano (CERN) for the simulations of rf field profile in the QPR allowing to define the area to be laser treated and the useful discussions with Sergey Arsenyev (CERN) on beam impedance. The laser structuring at the University of Dundee was conducted under the aegis of grants and financial support from the STFC (Grant No. ST/P00086X/1) and CERN (Collaboration Agreement No. KN3362).
Publisher Copyright:
© 2019 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the »https://creativecommons.org/licenses/by/4.0/» 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.
PY - 2019/6/20
Y1 - 2019/6/20
N2 - The surface resistance of copper samples with an amorphous carbon (a-C) coating or with laser surface structuring, the surface treatments of choice for electron cloud suppression in critical cryogenic sectors of the high-luminosity upgrade of the Large Hadron Collider (HL-LHC), has been measured for the first time at a cryogenic temperature using the quadrupole resonator at CERN. Three different frequencies of relevance for evaluating beam impedance effects, namely, 400, 800, and 1200 MHz, have been investigated. No significant increase in surface resistance is observed for the a-C coating, compared to plain copper. In the case of laser structuring, the surface resistance depends on the direction of the surface currents relative to the laser-engraved groove pattern. The increase is minimal for parallel patterns, but in the perpendicular case the surface resistance increases considerably. Radio frequency (rf) heating from wake losses would then also increase in the HL-LHC case; however, the reduction in the power deposited onto the cold surfaces thanks to electron cloud suppression would still outweigh this effect.
AB - The surface resistance of copper samples with an amorphous carbon (a-C) coating or with laser surface structuring, the surface treatments of choice for electron cloud suppression in critical cryogenic sectors of the high-luminosity upgrade of the Large Hadron Collider (HL-LHC), has been measured for the first time at a cryogenic temperature using the quadrupole resonator at CERN. Three different frequencies of relevance for evaluating beam impedance effects, namely, 400, 800, and 1200 MHz, have been investigated. No significant increase in surface resistance is observed for the a-C coating, compared to plain copper. In the case of laser structuring, the surface resistance depends on the direction of the surface currents relative to the laser-engraved groove pattern. The increase is minimal for parallel patterns, but in the perpendicular case the surface resistance increases considerably. Radio frequency (rf) heating from wake losses would then also increase in the HL-LHC case; however, the reduction in the power deposited onto the cold surfaces thanks to electron cloud suppression would still outweigh this effect.
UR - http://www.scopus.com/inward/record.url?scp=85069746772&partnerID=8YFLogxK
U2 - 10.1103/PhysRevAccelBeams.22.063101
DO - 10.1103/PhysRevAccelBeams.22.063101
M3 - Article
AN - SCOPUS:85069746772
SN - 2469-9888
VL - 22
JO - Physical Review Accelerators and Beams
JF - Physical Review Accelerators and Beams
IS - 6
M1 - 063101
ER -