Safety and protection of 8 T NbTi gyrotron magnet in persistent mode

To achieve high mechanical stability of a superconducting winding, numerical stress-strain analyses of the winding structure and appropriate stress-strain analyses of the winding structure and appropriate epoxy-impregnation technology were applied. To improve further winding mechanical stability, an initially round 1-mm-diameter varnish-insulated conductor was flattened to rack-track cross section (1.25 mm*0.75 mm for the inner section, 1.31 mm*0.65 mm for the rest of the magnet). The stainless steel road (1 mm diameter) of the bandage was flattened in the same way (up to 1.14 mm*0.77 mm). The danger of creating a hot spot region was limited by radial magnet sectioning and section shunting by low ohmic shunts. The superconducting switch was protected by a pair of antiparallel silicon diodes mounted between magnet flanges in parallel to it. The high threshold voltages of the diodes at 4.2 K allow system run-up with relatively high speed without any limitation on the sign of the magnet field polarity.