Interstrand resistance of selected sections of DCA312

The quench current ramp rate sensitivity of the full length SSC dipole DCA312 was strongly A-type and the eddy current losses for this magnet were the largest of all ASST magnets. The quench current remained constant with ramp rate up to approximately 20 A/s. At higher ramp rates the quench current decreased dramatically. At a current ramp rate of 200 A/s the quench current was only 2000 A. The eddy current losses of DCA312 at 60 A/s for a monopolar cycle of 500A-5000A-500A were approximately 3600 J/Cycle, a factor of 5--7 larger than for magnets DCA311, DCA319, and DCA318. In order to find the cause of the anomalous behavior of DCA312, it was decided that the magnet would be cut into sections and examined at WMSD and SSCL. The general goals of the DCA312 autopsy included verification of theoretical models for A-type behavior in SSC magnets as well as correlation of fabrication and assembly procedures to the quench behavior of A-type magnets. One of the important aspects of the magnet autopsy plan was the in-situ measurement of interstrand resistance in collared magnet sections. Four sections of DCA312 were designated for interstrand resistance measurements. Two of those sections (C and M) contained quench sites (100 A/s and 200 A/s respectively) and two of them (E and J) were sections representative of the magnet where quenches did not occur. The aim of the present work was to measure and analyze the interstrand resistance in each quadrant of these four sections of DCA312 and to find a correlation between the measured interstrand resistance, the actual resistance of individual interstrand contacts, and the quench performance of the magnet