Upgraded multiprobe sample inserts for thin film SRF cavity developments

Optimisation of thin film (TF) coating parameters for
producing SRF cavities requires rapid testing of supercon-ducting properties. A dedicated multiprobe facility built at Daresbury Lab, based on a liquid He free cryocooler, allows such measurements to be performed. The facility has vac-uum tubular inserts where the sample probe is loaded and cooled with He gas. The experimental inserts were either newly built or upgraded: (1) A DC resistance experiment
allows measurements of critical temperature (𝑇c) and resid-ual resistance ratio (𝑅𝑅𝑅) on non-conductive substrates (e.g. sapphire). A newly designed insert allows better temperature control and easier sample change. (2) A new insert for magnetic field measurements of 𝑇c on both conductive and non-conductive substrates. (3) An existing insert for planar magnetic field penetration experiments was significantly redesigned. It operates at lower temperatures (> 5.5 K), par-allel magnetic fields < 600 mT, increased sensitivity, and enables measurements of field of first flux penetration (𝐵fp) and 𝑇c on various substrates: copper and sapphire, the latter of which was impossible to measure with an older design