Design and performance of an HTS current comparator for charged-particle-beam measurements

Superconducting direct current comparators are well established for operati on at liquid helium temperatures, We have begun investigations into HTS Cry ogenic Current Comparator designs, which incorporate a flux concentrator an d readout SQUID also made from HTS. This work aims to produce a system capa ble of high accuracy, non-invasive, measurements of an ion or electron beam current in the range similar to 10 nA to 1mA. We outline a proposal for a precise determination of the faraday fundamental constant, using purely phy sical systems, and employing an HTS CCC for charged particle beam current m easurement. In addition estimates of the potential current sensitivity are reported, based on measurement results of a prototype system, and proof-of- principle measurements of ion beam currents are described. The design and c onstruction of a robust, compact cryogenic unit suitable for further, more realistic, field trials are discussed.