Author: Parajuli, I.P.
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SUPFDV015 Preliminary Results from Magnetic Field Scanning System for a Single-Cell Niobium Cavity 96
 
  • I.P. Parajuli, G. Ciovati, J.R. Delayen, A.V. Gurevich
    ODU, Norfolk, Virginia, USA
  • G. Ciovati, J.R. Delayen
    JLab, Newport News, Virginia, USA
 
  One of the building blocks of modern particle accelerators is superconducting radiofrequency (SRF) cavities. Niobium is the material of choice to build such cavities, which operate at liquid helium temperature (2 - 4 K) and have some of the highest quality factors found in Nature. There are several sources of residual losses, one of them is trapped magnetic flux, which limits the quality factor in SRF cavities. The flux trapping mechanism depends on different niobium surface preparations and cool-down conditions. Suitable diagnostic tools are not yet available to study the effects of such conditions on magnetic flux trapping. A magnetic field scanning system (MFSS) for SRF cavities using Hall probes and Fluxgate magnetometer has been designed, built, and is commissioned to measure the local magnetic field trapped in 1.3 GHz single-cell SRF cavities at 4 K. In this contribution, we will present the preliminary results from MFSS for a single cell niobium cavity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-SUPFDV015  
About • Received ※ 21 June 2021 — Revised ※ 13 August 2021 — Accepted ※ 08 November 2021 — Issue date ※ 27 April 2022
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WEPFDV008 Thermal Conductivity of Electroplated Copper Onto Bulk Niobium at Cryogenic Temperatures 576
 
  • G. Ciovati, P. Dhakal
    JLab, Newport News, Virginia, USA
  • I.P. Parajuli, M.R.P. Walive Pathiranage
    ODU, Norfolk, Virginia, USA
  • T. Saeki
    KEK, Ibaraki, Japan
 
  Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
Superconducting radio-frequency (SRF) cavities made of high-purity bulk niobium are widely used in modern particle accelerators. The development of metallic outer coatings with high thermal conductivity would have a beneficial impact in terms of improved thermal stability, reduced material cost and for the development of conduction-cooled, cryogenic-free SRF cavities. Several high-purity, fine-grain Nb samples have been coated with 2’4 mm thick copper by electroplating. Measurements of the thermal conductivity of the bimetallic Nb/Cu samples in the range 2’7 K showed values of the order of 1 kW/(m K) at 4.3 K. Very good adhesion between copper and niobium was achieved by depositing a thin Cu layer by cold spray on the niobium, prior to electroplating the bulk Cu layer.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-WEPFDV008  
About • Received ※ 17 June 2021 — Accepted ※ 10 September 2021 — Issue date; ※ 01 March 2022  
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