RMs1: The state of the art SWaP cryocooler

For five years, Thales Cryogenics has led a new development cycle in order to design and deliver a new generation of SWaP cryocoolers. Both linear and rotary Stirling coolers have been developed. SWaP coolers are especially designed to cool the emerging High Operating Temperature IR detector (HOT). Insofar as optimal detector performance for HOT technologies are still challenging, Thales forced himself to develop a rotary cooler that can cool detector at intermediate cold temperatures, ie. 90 to 140K, even if the optimal performances are reached for 150K. A first demonstrator was shown during the SPIE DS 2015 exhibition. That prototype was useful to investigate technologies to be introduced in order to drastically improve the compactness and the weight. Both aspects were reduced by 50% compared to a legacy RM2. The achieved compactness was identified as an optimal trade-off between mass and volume versus the associated production costs. Last year, Thales worked on new prototypes of the RMs1 SWaP rotary cooler. That product is the results of the previous RT and design phases, on one hand, and the adoption of generic standards on interfaces like the cold finger in order to simplify integration – and thus reduce overall cost – by our customers on the other hand. Associated performances were presented and commented. The current paper is focused on the qualification results obtained at the end of 2017. Especially, the available cooling power versus the cold temperature will be shared, next to other important key cryogenics performances such as the cool down time for dedicated detectors, characterized by a thermal masses and operational temperatures. Moreover, a particular effort has been made on other "soft" performances, in order to greatly improve the user experience, that is to say noise and induced vibrations. At last, first lifetime figures for the RMs1 are also presented and commented. As a conclusion, the compliance of the RMs1 performances with expectations for HOT IR detectors is discussed, in order to highlight the next steps of the development of the SWaP cryocoolers.