Author: Koral, C.
Paper Title Page
MOPAB346 Broadband Frequency Electromagnetic Characterisation of Coating Materials 1076
 
  • A. Passarelli, C. Koral, M.R. Masullo
    INFN-Napoli, Napoli, Italy
  • A. Andreone
    Naples University Federico II, Napoli, Italy
  • M. De Stefano
    University of Naples, Naples, Italy
  • V.G. Vaccaro
    Naples University Federico II and INFN, Napoli, Italy
 
  In the new gen­er­a­tion of par­ti­cle ac­cel­er­a­tors and stor­age rings, col­lec­tive ef­fects have to be care­fully an­a­lyzed. In par­tic­u­lar, the fi­nite con­duc­tiv­ity of the beam pipe walls is a major source of im­ped­ance and in­sta­bil­i­ties. A re­li­able elec­tro­mag­netic (EM) char­ac­ter­i­sa­tion of dif­fer­ent coat­ing ma­te­ri­als is re­quired up to hun­dreds of GHz due to very short bunches. We pro­pose two dif­fer­ent mea­sure­ment tech­niques for an ex­tended fre­quency char­ac­ter­i­za­tion: (i) a THz time do­main setup based on the sig­nal trans­mis­sion re­sponse of a tai­lored wave­guide to infer the coat­ing EM prop­er­ties from 100 to 300 GHz or even fur­ther*.**. This tech­nique has been tested both on NEG and amor­phous Car­bon films. (ii) a res­o­nant method, based on di­elec­tric cav­i­ties, to eval­u­ate the sur­face re­sis­tance Rs of thin con­duct­ing sam­ples at low (GHz) fre­quen­cies***. Due to its high sen­si­tiv­ity, Rs val­ues can be ob­tained for very thin (nano­met­ric) coat­ings or for cop­per sam­ples with a laser treated sur­face, since they have an ex­pected con­duc­tiv­ity very close to bulk cop­per.
*A. Passarelli et al., Phys. Rev. Accel. Beams, v.21, p.103101, 2018
**A. Passarelli et al., Cond. Matter, v.5, p.9, 2020
***A. Andreone et al., Applied Physics Letters, v.91, n.7, p.072512, 2007
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB346  
About • paper received ※ 18 May 2021       paper accepted ※ 09 June 2021       issue date ※ 26 August 2021  
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