33.6 T d.c. magnetic field produced in a hybrid magnet with Ho pole pieces

A dc magnetic field of 33.6±0.3 T was produced in a hybrid magnet whose central field was enhanced by a 3.5 T contribution from holmium pole pieces. The working (sample) volume was a 2-mm gap between the 19-mm-diam×32-mm-long pole pieces tapered to 12-mm-diam faces. The magnetic field was measured with high-field/low-temperature Hall-effect sensors whose reproducibility and linearity made practical an extrapolation technique for fields above 30 T. Three superconducting samples with previously measured upper critical fields were used as calibration check points.