Superconducting 500 MHz accelerating copper cavities sputter-coated with niobium films
Thermal breakdown induced either by electron loading or by local defects of enhanced RF losses limits the accelerating field of superconducting niobium cavities. Replacing niobium with a material of higher thermal conductivity would be highly desirable to increase the maximum field. Therefore, cavities made of OFHC copper were coated by D.C. bias sputtering with a thin niobium film (1.5 to 5 ..mu..). Accelerating fields up to 8.6 MVm/sup -1/ were obtained without observing any field breakdown, the limitation being due to the available rf power. The Q values achieved at 4.2 K and low field were similar to those of niobium sheet cavities (i.e. about 2 x 10/sup 9/), but a fast initial decrease of Q to about 10/sup 9/ was reproducibly experienced. Subsequent inspection of regions of enhanced rf losses revealed defects the origin of which is under study. The apparatus used for coating the cavities and the results obtained are presented and discussed.
- Research Organization:
- CERN, Geneva
- OSTI ID:
- 6484842
- Report Number(s):
- CONF-840937-
- Journal Information:
- IEEE Trans. Magn.; (United States), Vol. MAG 21:2; Conference: Applied superconductivity conference, San Diego, CA, USA, 9 Sep 1984
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
36 MATERIALS SCIENCE
NIOBIUM
SPUTTERING
SUPERCONDUCTING CAVITY RESONATORS
PROTECTIVE COATINGS
SUPERCONDUCTIVITY
ACCELERATION
COPPER
CRYSTAL DEFECTS
DIFFUSION COATING
EQUIPMENT
LOSSES
MHZ RANGE 100-1000
Q-VALUE
RADIOWAVE RADIATION
THERMAL CONDUCTIVITY
THIN FILMS
CAVITY RESONATORS
COATINGS
CRYSTAL STRUCTURE
DEPOSITION
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTROMAGNETIC RADIATION
ELECTRONIC EQUIPMENT
ELEMENTS
ENERGY
FILMS
FREQUENCY RANGE
METALS
MHZ RANGE
PHYSICAL PROPERTIES
RADIATIONS
RESONATORS
SUPERCONDUCTING DEVICES
SURFACE COATING
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS
420201* - Engineering- Cryogenic Equipment & Devices
360101 - Metals & Alloys- Preparation & Fabrication