Design of Adjustable Homogeneous Region Cryofree Conduction-Cooled Superconducting Magnet for Gyrotron

A conduction cooled superconducting magnet with the center field from 1.3 to 4 T and the warm bore of 100 mm in diameter has designed, fabricated and tested. The magnet was designed on the basis of the hybrid genetic optimal method. The superconducting magnet has the adjustable homogenous regions with the lengths from 200 mm to 320 mm. The magnet generated the multi-homogeneous regions with the constant lengths of 200, 250 and 320 mm. The homogeneity of magnetic field is about plusmn0.5% with the constant homogenous region lengths and plusmn1.0% for adjusting homogenous lengths. The magnetic field is decayed to 1/15-1/20 from the front point of homogeneous region to 200 mm. The magnet is cooled by one 1.5 Watt 4 K GM refrigerator. In the paper, the results on the design, fabrication and test of the superconducting magnet are presented.