SRF2015 - List of Authors (Wright, N.T.)

Paper	Title	Page
MOPB007	Temperature Excursions in Nb Sheets With Imbedded Delamination Cracks	82
	P. Xu, N.T. Wright MSU, East Lansing, Michigan, USA T.R. Bieler Michigan State University, East Lansing, Michigan, USA C. Compton FRIB, East Lansing, Michigan, USA
	Funding: Work supported by US DOE Cooperative Agreement DE-SC0000661 and Michigan State University. Delamination cracks can form in rolled Nb sheets, and between layers with different micro-structures. Such cracks cause resistance to heat conduction from the RF surface to the liquid He bath. A delamination crack can negate the advances in manufacturing processes that have enhanced the thermal conductivity of Nb. Here, temperature excesses are calculated as functions of crack size and location, and the power dissipated at an imperfection in the RF surface. A disk shape of Nb sheet is modeled as having adiabatic sides. A hemispherical defect is located on the RF surface at the center of this section. A crack is modeled as a void within the Nb disk. The Kapitza resistance between the Nb surface and liquid He is varied. The results indicate that an incipient crack leads to a decrease in the magnetic flux required to cause thermal breakdown. The decrease in the field is gradual with increasing crack radius, until the crack radius nearly equals the section radius, after which the field required for breakdown decreases sharply. To a lesser extent, the field strength for thermal breakdown also decreases with increased crack depth.
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Paper

Title

Page

Temperature Excursions in Nb Sheets With Imbedded Delamination Cracks

82

P. Xu, N.T. Wright
MSU, East Lansing, Michigan, USA
T.R. Bieler
Michigan State University, East Lansing, Michigan, USA
C. Compton
FRIB, East Lansing, Michigan, USA

Funding: Work supported by US DOE Cooperative Agreement DE-SC0000661 and Michigan State University.
Delamination cracks can form in rolled Nb sheets, and between layers with different micro-structures. Such cracks cause resistance to heat conduction from the RF surface to the liquid He bath. A delamination crack can negate the advances in manufacturing processes that have enhanced the thermal conductivity of Nb. Here, temperature excesses are calculated as functions of crack size and location, and the power dissipated at an imperfection in the RF surface. A disk shape of Nb sheet is modeled as having adiabatic sides. A hemispherical defect is located on the RF surface at the center of this section. A crack is modeled as a void within the Nb disk. The Kapitza resistance between the Nb surface and liquid He is varied. The results indicate that an incipient crack leads to a decrease in the magnetic flux required to cause thermal breakdown. The decrease in the field is gradual with increasing crack radius, until the crack radius nearly equals the section radius, after which the field required for breakdown decreases sharply. To a lesser extent, the field strength for thermal breakdown also decreases with increased crack depth.

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reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text, ※ RIS/RefMan, ※ EndNote (xml)