• Open Access

Field emitter activation on cleaned crystalline niobium surfaces relevant for superconducting rf technology

A. Navitski, S. Lagotzky, D. Reschke, X. Singer, and G. Müller
Phys. Rev. ST Accel. Beams 16, 112001 – Published 13 November 2013

Abstract

The influence of heat treatments at 122, 400, and 800°C on the field emission of large-grain and single-crystal high-purity niobium samples has been investigated. Buffered chemical polishing of 40μm and high pressure ultrapure water rinsing under clean-room conditions resulted in smooth surfaces with a linear surface roughness of 46 to 337 nm. By means of field emission scanning microscopy, an increasing number of emitters up to 40/cm2 with temperature were found at surface fields up to 160MV/m. Two different mechanisms of emitter activation were found, i.e. activation by the applied electric field and activation by temperature. Some emitters with an onset surface field of 50 to 100MV/m appeared already after the low-temperature bakeout. Correlated scanning-electron-microscopy/energy-dispersive-x-ray measurements revealed particles and surface defects as emitters. Their activation will be discussed with respect to the thickness of the insulating oxide layer.

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  • Received 18 January 2013

DOI:https://doi.org/10.1103/PhysRevSTAB.16.112001

This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society

Authors & Affiliations

A. Navitski1,2,*, S. Lagotzky1, D. Reschke2, X. Singer2, and G. Müller1

  • 1University of Wuppertal, FB C Physics Department, 42097 Wuppertal, Germany
  • 2DESY, 22607 Hamburg, Germany

  • *Corresponding author. aliaksandr.navitski@desy.de

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Vol. 16, Iss. 11 — November 2013

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