Studies of Thin Films of Nb3 Sn on Nb

Experiments are described where thin layers of Sn about 100 Å thick are deposited on Nb surfaces and are then reacted to form Nb3Sn. An apparatus has been developed where the Nb3Sn can be made and its Tc measured in situ with ambient pressures in the low 10−8-Torr range. Using this apparatus, the progressive conversion of films of Sn on Nb to Nb3Sn have been studied as a function of various parameters such as reaction temperature, thickness, and reaction time. A discussion is also given of some of the film properties and estimates have been made of the Nb3Sn coherence length from the proximity effect between the Nb3Sn layers and the bulk Nb underneath.