Detection of the normal zone with cowound sensors in cable-in conduit conductors

Tokamaks in the future will use superconducting cable-in-conduit-conductors (CICC) in all Poloidal Field (PF) & Toroidal Field (TF) magnets. Conventional quench detection, the measurement of small resistive normal-zone voltages (<1 V) in the magnets will be complicated by the presence of large inductive voltages (>4 kV). In the quench detection design for TPX, we have considered several different locations for internal co-wound voltage sensors in the cable cross-section as the primary mechanism to cancel this inductive noise. The Noise Rejection Experiment (NRE) at LLNL has been designed to evaluate which internal locations will produce the best inductive-noise cancellation, and provide us with experimental data for comparison with developed earlier theory. The details of the experiments and resulting data are presented and analyzed.