Design and Construction of a 11-T Superconducting Magnet System With A 30 mm Diameter 4.2–400 K Bore

Abstract

This superconducting magnet system has five components: a two-coil 11-T superconducting magnet, 150 A power supply, a metallic inner dewar, 80-L liquid helium outer (magnet) dewar and their auxiliarys. The magnet is 40 mm in inner diameter and 257 mm in length. It has a stored energy of 73 kJ at a maximum field of 11 T. The inner coil is made of Nb₃Sn/Cu conductor (Cu:SC ≃ 4:1) and the outer uses NbTi/Cu conductor (Cu:SC ≃ 2.3:1). (Both superconductors are supplied by two Chinese Institutes). Full field is achieved at 50J of the short sample current density. The inner dewar provides a sample volume with a diameter of 30 mm which can be varied in temperature from 4.2 K to 400 K. Samples can be changed when the magnet is operating. The loss rate of the outer dewar itself is 0.17 litres per hour. At 10 T, with the temperature of the inner dewar at 70 K, the loss rate is approximately 1.3 litres per hour.