Superconducting Power Supply for the KEDR Main Superconducting Solenoid

The power supply based on the full-wave superconducting rectifier is used for excitation of the main superconducting solenoid of the KEDR universal magnetic detector at the VEPP-4 collider. The rectifier consists of the air-core superconducting transformer and two thermally controlled superconducting switches. Several superconducting switch designs were developed, in order to achieve appropriate parameters of the rectifier operation. The present version of the switches was designed and tested in November 2013. The rectifier is cooled with a liquid helium bath. The primary winding of the superconducting transformer is excited with an ac current amplitude of 28 A at a voltage amplitude of 5 V. The heat power used for a superconducting switch control is 2.7 W. The power supply provides rising the magnetic field inside the KEDR main solenoid, long-term stabilization, and lowering the field to zero. The inductance of the solenoid is 1.2 H. The usual operating magnetic field is 0.6 T, which corresponds to the 2.4-kA current in the solenoid winding and 3.46 MJ of stored energy. The power supply pumps the field up to 0.6 T, within 110 h, and can keep it constant for several months. In this paper, the design, parameters, and performance of the superconducting rectifier are discussed.