title: Operating Modes and Cooling Capabilities of the 3-Stage ADR Developed for the Soft-X-ray Spectrometer Instrument on Astro-H.
abstract: A 3-stage adiabatic demagnetization refrigerator (ADR)[1] is used on the Soft X-ray Spectrometer instrument[2] on Astro-H[3] to cool a 6×6 array of x-ray microcalorimeters to 50 mK. The ADR is supported by a cryogenic system[4] consisting of a superfluid helium tank, a 4.5 K Joule-Thomson (JT) cryocooler, and additional 2-stage Stirling cryocoolers that pre-cool the JT cooler and cool radiation shields within the cryostat. The ADR is configured so that it can use either the liquid helium or the JT cryocooler as its heat sink, giving the instrument an unusual degree of tolerance for component failures or degradation in the cryogenic system. The flight detector assembly, ADR and dewar were integrated into the flight dewar in early 2014, and have since been extensively characterized and calibrated. This paper summarizes the operation and performance of the ADR in all of its operating modes.
authors.affiliation: NASA/Goddard Space Flight Center, Greenbelt, MD 20771 USA.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Shirron
authors.affiliation: NASA/Goddard Space Flight Center, Greenbelt, MD 20771 USA.
authors.forename: Mark O
authors.initials: MO
authors.lastname: Kimball
authors.affiliation: NASA/Goddard Space Flight Center, Greenbelt, MD 20771 USA.
authors.forename: Bryan L
authors.initials: BL
authors.lastname: James
authors.affiliation: NASA/Goddard Space Flight Center, Greenbelt, MD 20771 USA.
authors.forename: Theo
authors.initials: T
authors.lastname: Muench
authors.affiliation: NASA/Goddard Space Flight Center, Greenbelt, MD 20771 USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: DiPirro
authors.affiliation: Bastion Technologies, 7515 Mission Drive, Suite 300 Lanham, MD 20706 USA.
authors.forename: Richard V
authors.initials: RV
authors.lastname: Letmate
authors.affiliation: SGT Inc., 7701 Greenbelt Road, Suite 400 Greenbelt, MD 20770 USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Sampson
authors.affiliation: NASA/Goddard Space Flight Center, Greenbelt, MD 20771 USA.
authors.forename: Tom G
authors.initials: TG
authors.lastname: Bialas
authors.affiliation: NASA/Goddard Space Flight Center, Greenbelt, MD 20771 USA.
authors.forename: Gary A
authors.initials: GA
authors.lastname: Sneiderman
authors.affiliation: NASA/Goddard Space Flight Center, Greenbelt, MD 20771 USA.
authors.forename: Frederick S
authors.initials: FS
authors.lastname: Porter
authors.affiliation: NASA/Goddard Space Flight Center, Greenbelt, MD 20771 USA.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Kelley