Author: Reschke, D.
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TUPOTK011 Commissioning of a New Magnetometric Mapping System for SRF Cavity Performance Tests 1215
SUSPMF106   use link to see paper's listing under its alternate paper code  
 
  • J.C. Wolff, J. Eschke, A. Gössel, D. Reschke, L. Steder, L. Trelle
    DESY, Hamburg, Germany
  • W. Hillert
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  Funding: This work was supported by the Helmholtz Association within the topic Accelerator Research and Development (ARD) of the Matter and Technologies (MT) Program.
Magnetic flux trapped in the niobium bulk material of superconducting radio frequency (SRF) cavities degrades their quality factor and the accelerating gradient. The sensitivity for flux trapping is mainly determined by the treatment and the geometry of the cavity as well as the niobium grain size and orientation. To potentially improve the flux expulsion characteristics of SRF cavities and hence the efficiency of future accelerator facilities, further studies of the trapping behavior are essential. For this purpose a magnetometric mapping system to monitor the magnetic flux along the outer cavity surface of 1.3 GHz TESLA-Type single-cell SRF cavities has been developed and is currently in the commissioning phase at DESY. Contrary to similar approaches, this system digitizes the sensor signals already inside of the cryostat to extensively reduce the number of required cable feedthroughs. Furthermore, the signal-to-noise ratio (SNR) and consequently the measuring sensitivity can be enhanced by shorter analog signal lines, less thermal noise and the Mu-metal shielding of the cryostat. In this contribution test results gained by a prototype of the mapping system are presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK011  
About • Received ※ 10 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 29 June 2022
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TUPOTK012 Nitrogen Infusion Sample R&D at DESY 1219
 
  • C. Bate
    University of Hamburg, Hamburg, Germany
  • A. Ermakov, D. Reschke, J. Schaffran
    DESY, Hamburg, Germany
  • W. Hillert, M. Wenskat
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  Funding: This work was supported by the Helmholtz Association within the topic Accelerator Research and Development (ARD) of the Matter and Technologies (MT) Program.
Many accelerator projects such as the ILC would benefit from cavities with reduced surface resistance (high Q-values) while maintaining a high accelerating gradient. A possible way to meet the requirements is the so-called nitrogen-infusion procedure on Niobium cavities. However, a fundamental understanding and a theoretical model of this method are still missing. One important parameter is the residual resistance ratio (RRR) which is related to the impurity content of the material. We report the investigated RRR on samples in a wide temperature range in a vacuum and under a nitrogen atmosphere. This comparison made it possible to make statements about the differences in the concentration of nitrogen by varying the temperature. The samples are pure cavity-grade niobium and treated in the same manner as cavities. For this purpose, a small furnace dedicated to sample treatment was set up to change and explore the parameter space of the infusion recipe. Care was taken to achieve the highest level of purity possible in the furnace and in a pressure range of 1.0·10-8 mbar in order to meet the high requirements of nitrogen infusion.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK012  
About • Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 01 July 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)