High gradient superconducting RF systems

Superconducting RF (SRF) cavities are a promising technology for the next generation of electron positron colliders. In order to apply SRF technology in such machines, accelerating gradients must be improved, from the 5 to 10 MV/m level achieved in accelerators today, to the range of 20 to 30 MV/m. The state of the art in high gradient SRF technology will be discussed. Topics include achieved cavity performance, fabrication, preparation, handling, and processing techniques. Significant progress, e.g. multi-cell cavities with gradients >25 MV/m and single-cell cavities with gradients >40 MV/m, has been achieved over the past several years towards the goal of increased gradients. The major improvements have been in the areas of understanding and reducing cavity loading due to field emission and thermal quenches