A cryogenic sensor maintains calibration at ≈4.2 K to better than 2 mK (<0.5 percent resistance repeatability) after being heated to ≈40 K with ≈0.5 W power. The sensor withstands 4 W power dissipation when immersed in liquid nitrogen with verified resistance reproducibility of, at worst, 1 percent. The sensor maintains calibration to 0.1 percent after being heated with 1-W power at ≈77 K for a period of 48 hours.
When operated with a readout scheme that is capable of mitigating the self-heating calibration errors, this and similar sensors can be used for precision (mK stability) temperature control without the need of separate heaters and associated wiring/cabling.
This work was done by Hyung J. Cho, Konstantin Penanen, Kalyani G. Sukhatme, and Warren A. Holmes of Caltech, and Scott Courts of Lake Shore Cryotronics for NASA’s Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Physical Sciences category. NPO-46882
This Brief includes a Technical Support Package (TSP).
Using Thin-Film Thermometers as Heaters in Thermal Control Applications
(reference NPO-46882) is currently available for download from the TSP library.
Don't have an account?
Overview
The document discusses the innovative use of thin-film thermometers, specifically the Lake Shore Cryotronics, Inc. Cernox™ SD package thermistor, as heating elements in thermal control applications. This approach combines temperature sensing and heating in a single device, which is particularly beneficial in precision applications where traditional separate systems may be cumbersome or less efficient.
The authors, K. Penanen, H.J. Cho, K.G. Sukhatme, W.A. Holmes from JPL, and S. Courts from Lake Shore Cryotronics, outline several significant challenges associated with using thermometers as heaters. These challenges include the ability of the thermometer to dissipate power levels much higher than those used for sensing, maintaining calibration stability under high power conditions, ensuring low thermal impedance for effective heat transfer, and having a resistance range suitable for heating across the relevant temperature spectrum.
The document highlights that the Cernox™ SD package thermistor is particularly well-suited for this dual role. It maintains calibration at approximately 4.2 K with a resistance repeatability of less than 0.5% after being heated to around 40 K with a power of about 0.5 W. Furthermore, it can withstand power dissipation of up to 4 W when immersed in liquid nitrogen, with a maximum resistance reproducibility of 1%. Notably, the sensor retains calibration to within 0.1% after being heated with 1 W power at approximately 77 K for 48 hours.
The report emphasizes that when paired with a readout scheme capable of mitigating self-heating calibration errors, these sensors can achieve precision temperature control with millikelvin stability. This capability eliminates the need for separate heating elements and the associated wiring, simplifying the design and potentially enhancing reliability in thermal control systems.
Overall, the document serves as a technical support package under NASA's Commercial Technology Program, aiming to disseminate aerospace-related developments with broader technological, scientific, or commercial applications. It encourages further exploration and collaboration in this area, providing contact information for additional inquiries.
