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Title AC Susceptibility measurements on surface treated Niobium samples - Influence of electropolishing and baking parameters on the surface crititical field
Type Poster materials / surface effects
Abstract The effects of low temperature heat treatment (baking) and electropolishing (EP) on the high-gradient performance of superconducting niobium cavities are of high interest for future electron-positron colliders and X ray free electron lasers. Niobium samples are investigated at 4.2 K using ac susceptibility measurements. The surface critical field and the shielding currents are investigated with respect to  the duration (12 hours to 28 days) and the temperature (100 C, 123 C and 144 C) of the UHV heat treatment. Secondly, the difference between chemically etched and electropolished samples has been studied. The surface superconductivity in a thin surface layer is utilized to study the influence of various surface treatments on the superconducting properties. Electropolishing raises the surface critical field by about 8%. A further increase by up to 20% is caused by the baking procedure.

List of authors...

Principle author first.

Last (Family) Name First Name (Initials only) Affiliation or Organization (abbreviations if possible)
Steffen B. DESY
Knabbe E.-A. DESY
Lilje L. DESY
Schmueser P. DESY
Casalbuoni S. University Hamburg
von Sawilski L. University Hamburg
Koetzler J. University Hamburg

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