{'fraction_non_alphanumeric': 0.019770408163265307, 'fraction_numerical': 0.0, 'mean_word_length': 5.5103734439834025, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 1, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Raytheon dual-use long life cryocooler development

Development of the Dual-Use Cryocooler (DUC) system has progressed substantially over the past two years, including the design, build and testing of a brassboard thermo-mechanical unit (TMU). Early design efforts were undertaken with simplicity as a goal, and as a result the brassboard TMU contained significantly less parts than typical space-level cryocoolers. Build time for the brassboard unit was extremely short, with the compressor being built in a matter of days as opposed to the more traditional timescale of weeks. The brassboard TMU was subjected to characterization testing in both horizontal and vertical orientations (to address sensitivity of the pulse-tube cold head to gravitational effects), and results from that set of tests have been correlated to the thermodynamic model. Several lessons were learned as the testing and correlation activities progressed, and improvements necessary to meet the intended performance objectives were identified for implementation in the deliverable system. Significant progress was made in terms of electronics development as well. Existing tactical assets were heavily modified for use with the DUC, including the addition of separate drive circuits for each compressor motor. The operating software was modified to enable features not found in typical tactical systems such as first-order active vibration cancellation. Ultimately, the brassboard electronics were used to drive passive loads as well as an actual (representative) tactical Stirling cryocooler.