JWST OTIS Cryogenic Vacuum Test, Part 2: Thermal Analysis

In Part II, we will provide an overview of the OTIS CV test thermal model development. A description of some of the driving limits and constraints will be provided, as well as how these influenced our test planning and eventual execution. One significant aspect of our pre-test planning is the method by which we optimized the OTIS CV test cooldown and warmup profiles using the thermal model by incorporating a feedback loop for driving helium shroud temperature. We will spend some time introducing the logic for this feedback loop, which traded test time versus model safety to determine the most efficient way to cool and warm the payload. Finally, we will take a look at how our pre-test predictions compared with our actual performance in the OTIS CV test.