Development of collar lamination strain gauges for coil stress measurements in superconducting accelerator magnets

A new type of strain gauge has been developed for measuring coil stresses in superconducting magnets. It consists of commercial film-type strain gauges mounted directly on the pole-tip area of coil collar laminations. These gauges are extremely simple to manufacture, calibrate, and install in prototype magnets. We discuss the motivation for and design of these gauges, present results from calibration tests performed at 300 K and 4.2 K, and compare these results with calibration of existing beam-type transducer gauges. We discuss calibration reproducibility, reliability, and accuracy. We also present preliminary coil stress measurements using these gauges in a model quadrupole magnet during the collaring, yoking, cool down, and excitation processes.