Quench protection circuits for superconducting magnets

In developing a scheme for the quench protection of the toroidal field (TF) and poloidal field (PF) superconducting magnets of the Tokamak Physics Experiment (TPX), an extensive review was performed of the design options and their performance characteristics. The general results and conclusions of these studies are reported herein. For tokamak magnets which have low enthalpy compared to their stored energy, quench protection requires the discharge of the stored energy at location(s) external to the magnets, typically in discharge resistors. Such discharge requires the interruption of large DC currents and the insertion of resistors using suitable DC circuit breaking methods. Since protection of the magnets is a crucial function, the system must be ultra-reliable, and new techniques are necessary.