The XRS low temperature cryogenic system ground performance tests results

The X-Ray Spectrometer (XRS) instrument is part of the Astro-E mission sche duled to launch early in 2000. Its cryogenic system is required to cool a 3 2-element array of X-ray microcalorimeters to 60-65 mK over a mission lifet ime of at least 2 years. This is accomplished using an adiabatic demagnetiz ation refrigerator (ADR) contained within a two-stage superfluid helium/sol id neon cooler. Goddard Space Flight Center is providing the ADR and helium dewar. The flight helium dewar was assembled in Sept. 1997 and subjected t o extensive thermal performance tests. This paper presents test results at both the subsystem and component levels. In addition, results of the low te mperature topoff performed in Japan with the engineering unit neon and heli um dewars are discussed. (C) 1999 Elsevier Science Ltd. All rights reserved .