DocumentCode :
2096954
Title :
Microscopic examination of field emission areas in superconducting Nb cavities
Author :
Moffat, D. ; Flynn, T. ; Hand, L. ; Kirchgessner, J. ; Noer, R. ; Padamsee, H. ; Rubin, D. ; Sears, J. ; Shu, Q.
Author_Institution :
Lab. of Nucl. Studies, Cornell Univ., Ithaca, NY, USA
fYear :
1991
fDate :
6-9 May 1991
Firstpage :
21
Abstract :
A superconducting cavity has been developed in which it is possible to expose a small region of the cavity, called the dimple, to very high surface RF electric fields. In a break-apart version of this cavity, the dimple is part of a demountable niobium end-plate which fits into the SEM/EDS system. Surface RF electric fields between 50 and 70 MV/m have been supported by the dimple in several tests. On subsequent SEM examination of the end-plates, many interesting features associated with emission were discovered. Each emission site is located at the center of a starburst shaped region of reduced secondary emission coefficient. At the center of these sites craters of molten niobium have often been found. Sometimes the sites contain features which look like nodules or ripples on the niobium surface.<>
Keywords :
beam handling equipment; cavity resonators; electron field emission; scanning electron microscope examination of materials; superconducting magnets; surface structure; Nb; dimple; end-plates; field emission areas; superconducting cavity; surface RF electric fields; Assembly; Chemical elements; Electrodes; Electron emission; Inductors; Laboratories; Niobium; Radio frequency; Scanning electron microscopy; Testing;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Particle Accelerator Conference, 1991. Accelerator Science and Technology., Conference Record of the 1991 IEEE
Conference_Location :
San Francisco, CA, USA
Print_ISBN :
0-7803-0135-8
Type :
conf
DOI :
10.1109/PAC.1991.164193
Filename :
164193
Link To Document :
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