Author: Chouhan, V.
Paper Title Page
MOPC093 Novel Field Emission Scanner for Surface Study of Niobium SRF Cavity 295
 
  • S. Kato, M. Nishiwaki, T. Noguchi
    KEK, Ibaraki, Japan
  • V. Chouhan
    GUAS, Kanagawa, Japan
  • P.V. Tyagi
    Sokendai, Ibaraki, Japan
 
  It is mandatory to investigate field emission on Nb SRF cavity systematically since strong field emission often limits the cavity performance. The field emission strength and the number of emission sites strongly depend on Nb surface properties which are determined by its surface treatment and handling. Field emission scanner (FES) developed allows us to measure a distribution of the field emitting sites over a sample surface at a given field strength along with its FE-SEM observation and energy dispersive x-ray analysis. FES consists of an anode needle driven by precise 3D stepping motors and an eucentric sample stage. The compact scanner was installed into the space between the object lens and the SEM sample holder. In addition, this system was newly equipped with a sample load-lock system for existing UHV suitcases. Therefore a sample coupon to be observed is hardly exposed to contaminants and dust particles during the transportation. In-situ heating of a sample coupon can be done during an experiment to simulate a baking process of a SRF cavity. This article describes development of the field emission scanner and its preliminary results of the application to niobium samples.