Novel Strand Position Detection System Using Thermistor Array for Next Generation Large Fusion Magnet Cable-in-Conduit Conductors

Currently, progress is made globally to construct the ITER, to test the feasibility of fusion at a large scale. However, to create a functional and commercial fusion reactor generator, a larger and powerful magnet is necessary. Such magnets are yet to be constructed, with concerns on structural integrity and performance. In cable in conduit (CIC) conductors the individual strand positions is one concern, due to the possibilities of non-uniform current distribution. Thus, knowing the position of individual strands is necessary. Many studies have been conducted in simulating the strand position. At the same time, it is necessary to physically map the positions of the strands, for confirmation and refinement of simulations. Previously, out lab conducted measurements using thermal imaging. The methodology was slicing a CIC conductor in sections, heating up a strand on one side and detecting the change in temperature on the other side by the thermal camera. The strand that heats up fastest should be the same one that was heated up on the other side, allowing a one-to-one matching. The results were promising, but struggled in identifying closely packed sections, due to response speed of the camera. To improve the response speed, it was suggested to use thermistor chips, capable of detecting changes in temperature in the form of voltage with little lag. This should allow the identification of the path that a single strand takes. In this paper, an array of thermistors was tested to see the feasibility of the method, and results will be shown.