Speaker
Description
NASA is considering a “probe” class mission with a far-infrared imaging and spectroscopy space telescope. A critical technology for this mission is an efficient, high capacity, low-temperature cryocooler with low exported vibrations to enable its cryogenic instruments to achieve exquisite sensitivity and low internal noise to observe far distant faint cosmic sources. This paper compares the performances of a JT cooler with 4He and 3He working fluids, in terms of cooling capacity, input power, and optimal operating pressures. The paper will also discuss the effects of switching working fluids on the thermal performance of recuperators and the JT throttle design. Next, the paper will discuss the sensitivities of the cooler performance to the heat sink temperatures and cooling temperatures. Flow performance test results with a flight compressor development unit using these two fluids will be presented, as well as predicted cooler performance based on the measured compressor performance data.
