I am searching for an alternative to chromel-alumel thermocouples for our stand. The point is to find something better to use in Ar-O2 plasma (approx. 400 °C, 1.0*10^(-3) Torr). The only relevant thing I've found was warning not to use them in vacuum for a long time but with no explanation. Does anyone have any experience in using them in such conditions?
P.S. The main idea is to prevent thermocouples from fracturing during long-termed experiments