Investigation on the stability of two-strand superconducting cable related with ramp-rate limitation

Ramp-rate limitation, which is known as the serious obstacle for fast charging operation of superconducting magnet, is investigated by the experiment of a two-strand sample conductor and the numerical analysis. During this ramp-rate limitation experiment, the sample showed quench recovery by current redistribution or irreversible 'cable quench' depending on the operation conditions. To investigate the recovery or the quench criterion, we performed precise numerical analysis considering both electro-magnetic and thermal interactions of the cable. With the minimal assumed parameters, the simulation result shows that the status of the low-current strand determines 'recovery' or 'cable quench' when the 'local quench' first occurs at the high-current strand. Heat transfer conditions of the cable such as boiling heat transfer and contact heat transfer between the strands as well as the current non-uniformity are critical factors for the stability criterion. This paper describes the most fundamental cable quench recovery process that is influenced by field-ramping condition of the superconducting cable. (C) 2004 Elsevier B.V. All rights reserved.