Niobium Superconducting Cavities and Materials/Surface Sciences ―Development of 50 MV/m High Gradient Superconducting Cavity, Battles in those two decades―

Abstract

Recently accelerating gradient with superconducting RF cavity has been very much upgraded up to 50MV/m. It took more than twenty years. In this paper, the battles on various materials/surface scientific issues in the those two decades are historically reviewed on the long term cavity R&D.