Production run of 2 cm diameter YBCO trapped field magnets with surface field of 2 T at 77 K

A production run of 60 melt-textured YBCO trapped field magnets (TFMs), 2 cm in diameter, is reported. The TFMs have pinning centers of Y211 and (Pt0.4U0.6)YBa3O6 deposits and also damage tracks of ions from uranium fission. The resulting average trapped field at the center of the seed-side surface is 〈BT(r = 0)〉 = 2.04 T at 77 K. The rms spread in BT is 5.9%. TFM samples rejected due to problems with the SmBCO seeds totaled ~10%, and an additional 2% were lost due to cracking under magnetic pressure. Methods to significantly reduce these losses are discussed. The ratio of BT on the TFM bottom to that on the seed side is ~67%. Evidence of a method to raise this ratio to 1.0 is presented. The magnitude and time dependence of the radioactivity resulting from the uranium fission are reported.