Study of Low Temperature Baking Effect on Field Emission on Nb Samples Treated by BEP, EP, and BCP

Conference · Sat May 01 04:00:00 EDT 2010

OSTI ID:1020710

Field emission is still one of the major obstacles facing Nb superconducting radio frequency (SRF) community for allowing Nb SRF cavities to reach routinely accelerating gradient of 35 MV/m that is required for the international linear collider. Nowadays, the well know low temperature backing at 120 oC for 48 hours is a common procedure used in the SRF community to improve the high field Q slope. However, some cavity production data have showed that the low temperature baking may induce field emission for cavities treated by EP. On the other hand, an earlier study of field emission on Nb flat samples treated by BCP showed an opposite conclusion. In this presentation, the preliminary measurements of Nb flat samples treated by BEP, EP, and BCP via our unique home-made scanning field emission microscope before and after the low temperature baking are reported. Some correlations between surface smoothness and the number of the observed field emitters were found. The observed experimental results can be understood, at least partially, by a simple model that involves the change of the thickness of the pent-oxide layer on Nb surfaces.

• Research Organization: Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: AC05-06OR23177
• OSTI ID: 1020710
• Report Number(s): JLAB-ACC-11-1378; DOE/OR/23177-1598
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
BAKING
CAVITIES
FIELD EMISSION
LINEAR COLLIDERS
MICROSCOPES
NIOBIUM
RF SYSTEMS
ROUGHNESS
SUPERCONDUCTING CAVITY RESONATORS
SURFACES
TEMPERATURE RANGE 0273-0400 K
THICKNESS