Stirling cycle cryocooler exported vibration analysis

Abstract

The Australian National University (ANU), we are undertaking to deploy a Lucky Imaging instrument on the 2.3 m telescope at Siding Springs using a Leonardo SAPHIRA near-infrared electron Avalanche Photo-Diode (eAPD) array, capable of high cadence imaging with frame rates of 10 - 5,000 Hz over the wavelength range of 0.8 μm to 2.5 μm. compact cryocooler capable of cooling the Leonardo SAPHRA APD and associated cryogenic electronics to temperatures below 100K with little to no vibration. An ideal candidate cryocooler is the Sunpower Cryotel GT with active vibration cancellation. The Cryotel GT is an orientation independent, Stirlng cycle cooler with water jacket heat rejection. This cooler will meet the system cooling requirements. The cryocooler has been integrated with the APD Lucky Imager cryostat through 3 rubber isolating mounts and bellows and tested while suspended from a stable frame. The tethers supporting the cryostat and cooler assembly are not attached to the cryostat and cooler. The exported vibration was measured simultaneously in all 3 axis on the external cryostat wall and internally on the cryostat getter attached directly to the cold tip of the cooler. The test results were collected while the cryocooler was cooling and at the stable set point, at various levels of cooling power and with thermal control enabled and disabled.