Sensor placement in temperature-based control strategies to improve baseline stability in Tian-Calvet microcalorimeters

摘要

We address the issue of hardware placement in the development of robust temperature control strategies that can be used to maintain a stable baseline during microcalorimetric experiments. The two different control loops, each defined by the location of sensor within the calorimeter that is used to achieve control, were first developed and then tested in a fully instrumented experimental system. Both control strategies were structured on proportional-integral-derivative controllers, after which calorimetric experiments were carried out to test the efficiency and robustness of the corresponding methodology. Results indicate that sensor placement plays a fundamental role in the controlled baseline stability and that is better to place the sensing device closer to the heater than to the central core. As part of this study, comparisons were also done against a previously reported control scheme based on heat-flow measurements. Results indicate that controlling only one variable, either temperature or heat flow is sufficient to compensate for heater-induced noise, but not for external fluctuations for which a combined strategy may be necessary.