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Baumgart, H.

Paper Title Page
TUPPO041 TEM Study of Niobium Surfaces Treated by Different Polishing Techniques 300
 
  • A.T. Wu
    JLAB, Newport News, Virginia
  • H. Baumgart, D. Gu
    ODU, Norfolk, Virginia
  
 

TEM cross-section observation on Nb surfaces has been a challenge to our superconducting radio frequency (SRF) community due to the highly reactive nature of Nb. Although it was demonstrated in an early attempt1 that under a suitable sample preparation procedure reasonably clear cross-section images of Nb could be obtained, to the best of our knowledge good atomically resolved images had never been obtained. In this report, it is shown that by modifying the sample preparation procedure adopted in reference 1 it is possible to obtain good cross-section images of Nb surfaces with atomic resolution routinely. Surface atomic structures of Nb samples prepared by buffered electropolishing (BEP), buffered chemical polishing (BCP), and an untreated sample will be reported and compared.


1: A.T. Wu, Proc. of the 11th SRF Workshop, Germany, (2003), ThP13

  
TUPPO084 RF and Structural Characterization of New SRF Films 431
 
  • A-M. Valente-Feliciano, H.L. Phillips, C.E. Reece, X. Zhao
    JLAB, Newport News, Virginia
  • H. Baumgart, D. Gu
    ODU, Norfolk, Virginia
  • R.A. Lukaszew, B. Xiao
    The College of William and Mary, Williamsburg
  • K.I. Seo
    NSU, Newport News
  
 

In the past years, energetic vacuum deposition methods have been developed in different laboratories to improve Nb/Cu technology for superconducting cavities. JLab is pursuing energetic condensation deposition via Electron Cyclotron Resonance. As part of this study, the influence of the deposition energy on the material and RF properties of the Nb thin film is investigated. The film surface and structure analyses are conducted with various techniques like X-ray diffraction, Transmission Electron Microscopy, Auger Electron Spectroscopy and RHEED. The microwave properties of the films are characterized on 50 mm disk samples with a 7.5 GHz surface impedance characterization system. This paper presents surface impedance measurements in correlation with surface and material characterization for Nb films produced on copper substrates with different bias voltages and also highlights emerging opportunities for developing multi-layer SRF films with a new deposition system.