June 28, 2015 to July 2, 2015
JW Marriott Starr Pass Resort
Etc/GMT-7 timezone

Study of Thermocurrents in SCRF cavities via measurements of the Seebeck Effect in niobium, titanium, and stainless steel thermocouples

Jun 30, 2015, 2:00 PM
Exhibit Hall (Arizona Ballroom)

Exhibit Hall (Arizona Ballroom)

Poster Presentation ICMC-01 - NbTi/Nb3Sn/A15 Processing and Properties M2PoD - Cryogenic Materials IV: Physical Properties


Victoria Cooley (University of Wisconsin-Madison)


The goals of Fermilab’s Superconductivity and Radio Frequency Development Department are to engineer, fabricate, and improve superconducting radio frequency (SCRF) cavities in the interest of advancing accelerator technology. Improvement includes exploring possible limitations on cavity performance and mitigating such impediments. This report focuses on investigating and measuring the Seebeck Effect observed in cavity constituents titanium, niobium, and stainless steel arranged in thermocouples. These junctions exist between cavities, helium jackets, and bellows, and their connection can produce a loop of electrical current and magnetic flux spontaneously during cooling. Such currents could induce trapped flux in cavity surfaces, and lead to loss of quality factor after cool down. Our findings show that welded junctions behave differently than intrinsic junctions, perhaps due to inter-diffusion of elements. An estimate of thermally-induced current is made from the observed voltages and resistivity of the components.

Primary author

Victoria Cooley (University of Wisconsin-Madison)


Mr A. Curtis Crawford (Fermilab) Lance Cooley (Fermilab)

Presentation materials