Ion bombardment effect on a Nb/Cu interface studied by RBS, NRS, SEM techniques

Abstract

Niobium is used to make cavities of high-energy particle accelerators because of its superconducting properties. The quality of radiofrequency superconducting cavities is closely related to the purity of the material surface. Tests are done on a single cell cavity made of a few μm thick niobium layer sputtered onto a copper cavity. The goal is to obtain adequate structure in order to get high acceleration fields as obtained in pure niobium cells. The cavity thus obtained should improve the thermal stability at high field. With this aim, carbon and oxygen contamination at the surface and at the interface of the Nb/Cu device are measured using RBS and NRS techniques. In order to simulate the energy deposition occurring during particle acceleration, Nb/Cu samples have been irradiated with a 600 keV argon beam from 10¹⁶ to 3 × 10¹⁷ ions/cm². The element distribution evolution is then followed by RBS. The surface topography is evaluated using SEM.