MAGNET DESIGN AND CONSTRUCTION OF A 500 J PULSED SMES

The final aim of this study is to build a transformer showing performa nces very close to those computed for an instantaneous quench of its s uperconducting primary. We have built a 500 J superconducting transfor mer. Its associated quench inducing system is designed to drive the su perconducting primary completely normal. Hot spots as well as overvolt ages may appear inside the primary winding of this pulsed transformer during a real quench. These overvoltages may reach 3 kV between turns of two neighbouring layers. Using the well-known normal zone propagati on velocities of the superconducting cable we used, we calculated that the primary winding temperature would not exceed 80 K. We also studie d the influence of quench development on the secondary current pulse. For the charge we chose, driving 50% of the primary in the normal stat e leads to a current pulse very close to the one calculated for an ins tantaneous quench. Using a quench inducing system made of five strip h eaters, we intend to achieve a complete transition of our transformer primary. The heaters, connected in parallel, are fed by a very short ( < 40 mu s) capacitor discharge. By means of this system we hope to ind uce the quench over the whole primary winding 3.5 ms after the capacit or discharge.