Metallurgical analysis and RF losses in superconducting niobium thin film cavities

Author

Bloess, D. ; Durand, C. ; Mahner, E. ; Nakai, H. ; Weingarten, W. ; Bosland, P. ; Mayer, J. ; Van Loyen, L.

Author_Institution

European Organ. for Nucl. Res., CERN, Geneva, Switzerland

Volume

7

Issue

2

fYear

1997

fDate

6/1/1997 12:00:00 AM

Firstpage

1776

Lastpage

1780

Abstract

Copper cavities with a thin niobium film - as used in the large electron positron collider LEP - would be also attractive for future linear colliders, provided the decrease of the Q-value with the accelerating gradient could be reduced. We aim at extracting the important parameters that govern this decrease. The dependence on the RF frequency is studied by exciting 500 MHz and 1500 MHz cavities in different modes. In addition we combined RF measurements for two 1500 MHz cavities of different RF performance with microscopic tests (AFM,TEM) on samples cut out of the same cavities. Their microstructural characterization in plan-view allows the extraction of the grain size and the defect densities.

Keywords

accelerator cavities; accelerator magnets; grain size; magnetic leakage; niobium; superconducting cavity resonators; superconducting magnets; superconducting thin films; type II superconductors; 1500 MHz; 500 MHz; Nb; RF losses; accelerating gradient; defect densities; grain size; large electron positron collider; linear colliders; metallurgical analysis; microstructural characterization; superconducting Nb film cavities; Acceleration; Atomic force microscopy; Copper; Electrons; Grain size; Niobium; Positrons; Radio frequency; Superconducting films; Testing;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.620927

Filename

620927