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Title: MEASUREMENT OF RF LOSSES DUE TO TRAPPED FLUX IN A LARGE-GRAIN NIOBIUM CAVITY

Abstract

Trapped magnetic field in superconducting niobium is a well known cause of radio-frequency (RF) residual losses. In this contribution, we present the results of RF tests on a single-cell cavity made of high-purity large grain niobium before and after allowing a fraction of the Earth’s magnetic field to be trapped in the cavity during the cooldown below the critical temperature Tc. This experiment has been done on the cavity before and after a low temperature baking. Temperature mapping allowed us to determine the location of hot-spots with high losses and to measure their field dependence. The results show not only an increase of the low-field residual resistance, but also a larger increase of the surface resistance for intermediate RF field (higher "medium field Qslope"), which depends on the amount of the trapped flux. These additional field-dependent losses can be described as losses of pinned vortices oscillating under the applied RF magnetic field.

Authors:
;
Publication Date:
Research Org.:
Thomas Jefferson National Accelerator Facility, Newport News, VA
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
922260
Report Number(s):
JLAB-ACC-07-778; DOE/OR/23177-0279
TRN: US0801042
DOE Contract Number:  
AC05-06OR23177
Resource Type:
Conference
Resource Relation:
Conference: 13th Workshop on RF Superconductivity, Beijing, China, Oct. 14 - 19, 2007
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; BAKING; CRITICAL TEMPERATURE; NIOBIUM; SUPERCONDUCTING CAVITY RESONATORS; RF SYSTEMS; LOSSES

Citation Formats

Gianluigi Ciovati, and Alex Gurevich. MEASUREMENT OF RF LOSSES DUE TO TRAPPED FLUX IN A LARGE-GRAIN NIOBIUM CAVITY. United States: N. p., 2008. Web.
Gianluigi Ciovati, & Alex Gurevich. MEASUREMENT OF RF LOSSES DUE TO TRAPPED FLUX IN A LARGE-GRAIN NIOBIUM CAVITY. United States.
Gianluigi Ciovati, and Alex Gurevich. Wed . "MEASUREMENT OF RF LOSSES DUE TO TRAPPED FLUX IN A LARGE-GRAIN NIOBIUM CAVITY". United States. https://www.osti.gov/servlets/purl/922260.
@article{osti_922260,
title = {MEASUREMENT OF RF LOSSES DUE TO TRAPPED FLUX IN A LARGE-GRAIN NIOBIUM CAVITY},
author = {Gianluigi Ciovati and Alex Gurevich},
abstractNote = {Trapped magnetic field in superconducting niobium is a well known cause of radio-frequency (RF) residual losses. In this contribution, we present the results of RF tests on a single-cell cavity made of high-purity large grain niobium before and after allowing a fraction of the Earth’s magnetic field to be trapped in the cavity during the cooldown below the critical temperature Tc. This experiment has been done on the cavity before and after a low temperature baking. Temperature mapping allowed us to determine the location of hot-spots with high losses and to measure their field dependence. The results show not only an increase of the low-field residual resistance, but also a larger increase of the surface resistance for intermediate RF field (higher "medium field Qslope"), which depends on the amount of the trapped flux. These additional field-dependent losses can be described as losses of pinned vortices oscillating under the applied RF magnetic field.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2008},
month = {1}
}

Conference:
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