Characterization testing of Lockheed Martin Micro1-2 cryocoolers for the Mapping Imaging Spectrometer for Europa (MISE) instrument

Abstract

Abstract The Mapping Imaging Spectrometer for Europa (MISE) instrument on the Europa Clipper mission will use a Lockheed Martin “high-power” Micro1-2 pulse tube cryocooler with a heat rejection temperature below 250 K. This paper describes the performance testing and results of Lockheed Martin Micro1-2 coolers optimized for these conditions. The heat reject temperature varied between 170 K and 260 K for different helium fill pressures. The coolers were driven with input powers ranging from 5 W to 40 W and drive frequency between 125 Hz and 150 Hz. For all conditions measured, the heat flow from the compressor was between 54% and 58% of the total heat and the compressor temperature was between 4 K and 6 K warmer than the expander temperature. In addition, another Micro1-2 cooler optimized for 300 K environment was subjected to a life test at reject temperatures below 250 K. The cooler performance and helium leak rate did not change over the duration of the life test. Moreover, a burst test was performed on a unit of this model of cooler that was without the internal components. Finally, a method for developing analytical expressions to curve fit cooler performance data is presented. These expressions are provided and predict cooler performance to within 15% for a fixed drive frequency over a range of cold tip temperature, heat reject temperature, and input power.