Strain gauges for superconducting magnet testing

Abstract A survey of commercially available strain gauges potentially suitable for testing of superconducting magnets is presented. Strain measurement errors caused by magnetic fields and temperature changes are discussed. Previously unpublished data for the magnetic field induced error for weldable half-bridge strain gauges are given, along with the results of a test for the temperature dependence of the magnetorestistance of modified Karma alloy foil gauges in the liquid helium temperature range. Apparent strain-vs-temperature curves for the weldable half-bridge gauges and metal foil gauges are shown. Errors caused by magnetic fields are in general repeatable from gauge to gauge, whereas errors due to temperature effects exhibit considerable variation from gauge to gauge in a lot of nominally identical gauges.