Development of a superconducting protection switch for the HERA P-ring: design study and demonstration models

The electrical circuit of the HERA (Hadron Electron Ring Accelerator) proton ring (p-ring) is divided in octants so that in the case of a quench, the current has to be commutated to dumping resistors. The authors describe the application of superconducting switches which would enable the main circuit to remain at 4 K during a quench while the current is forced to flow through instantaneously loaded leads and dumping resistors. The main specifications of the required switches are: current of 6.5 kA, minimum off-resistance 12 Omega , energy absorbed 1 MJ, and self protecting. The various design and feasibility aspects of superconducting switches for this application are discussed. The requirement of being passively protected against a self-quench is considered the most critical design problem. It is still uncertain whether it remains necessary to apply an active protection scheme to enable safe operation of the switch.