Quench detection & instrumentation for the Tokamak Physics Experiment magnets

Abstract

The design of the Local Instrumentation & Control (I&C) System for the Tokamak Physics Experiment (TPX) superconducting PF & TF magnets is presented. The local I&C system monitors the status of the magnet systems and initiates the proper control sequences to protect the magnets from any foreseeable fault. Local I&C also stores magnet-system data for analysis and archiving. Quench Detection for the TPX magnets must use a minimum of two independent sensing methods and is allowed a detection time of one second. Proposed detection methods include the measurement of; (1) normal-zone resistive voltage, (2) cooling-path helium flow, (3) local temperature in the winding pack, (4) local pressure in the winding pack. Fiber-optic based isolation systems are used to remove high common-mode magnet voltages and eliminate ground loops. The data acquisition and fault-detection systems are computer based. The design of the local I&C system incorporates redundant, fault-tolerant, and/or fail-safe features at all component levels. As part of a quench detection R&D plan, a Quench Detection Model Coil has been proposed to test all detection methods. Initial cost estimates and schedule for the local I&C system are presented.