About the session
Most superconducting cavities are built from niobium sheets. A cost effective alternative approach is to sputter coat micrometer thin niobium films on copper cavities, developed for LEP-II and currently in use for LHC and HIE-Isolde. The performance of such thin film cavities is limited by the field dependent RF residual surface resistance. Several new techniques are currently being developed to overcome this limitation. HiPIMS is very similar to the standard dcMS. Films have been deposited and tested on 1.3 GHz test cavities. Other coating techniques like electron cyclotron resonance (ECR) are not yet developed to be deposited on cavities. Here sample tests are necessary to test the RF performance. A suitable device which can measure the surface resistance with unpreceded accuracy is the Quadrupole Resonator from CERN, which has more recently been rebuilt and further developed at HZB. Additionally DC methods can be used to probe the superconducting properties of samples and guide the development of the coating process. Two techniques which have been proven to be very informative for SRF developments are muon spin rotation and point contact tunneling. This article reviews RF and DC methods and results on test cavities and samples for SRF application.
