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X-Ray Calorimeter ~ Concept Presentation ~

X-Ray Calorimeter ~ Concept Presentation ~. ADR, HTS Leads, ADR Electronics Peter Shirron/552, Michael DiPirro/552, Tom Bialas/564 Feb 17, 2012. Block Diagram - Cryostat. x-rays. Aperture Cylinder & op htr. Aperture cover. KEY. filters. Detector 50 mK stage. main shell.

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X-Ray Calorimeter ~ Concept Presentation ~

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  1. X-Ray Calorimeter ~ Concept Presentation ~ ADR, HTS Leads, ADR Electronics Peter Shirron/552, Michael DiPirro/552, Tom Bialas/564 Feb 17, 2012

  2. Block Diagram - Cryostat x-rays Aperture Cylinder & op htr Aperture cover KEY filters Detector 50 mK stage main shell Calorimeter/ADR insert Vent valve Focal Plane Assembly (FPA) at 50mK 50 mK filters conductive bond Microcalorimeter SQUID readout amplifiers Antico detector thermal link heat switch 3-stage Adiabatic Demagnetization Refrigerator (ADR) superconducting cable ADR Stage 1 50 mK cryostat shells 4K SQUIDs & termination resistors ADR Stage 2 Calorimeter/ADR Insert 0.6 K Detector Control ADR Stage 3 1.8 K Custom cryostat encloses the FPA and ADR, as well as the readout amplifiers ADR Control 4.5 K JT stage 18 K 75 K 260-300 K cold head Loop Heat Pipe to radiator Commercial Cryocooler Cryocooler Compressors

  3. ADR Design Drivers • Heat load at 50 mK • Significantly reduced from earlier concepts using large format detector arrays • Heat sink and heat rejection rate • 4-5 K has been baseline for instrument concepts (4.5 K assumed for this study) • 20 mW of cooling at 5 K is significantly less (~10 mW assumed for ADR) • Magnetic field control • Designs from Astro-H are close to the level of control needed • Temperature stability • Single-shot designs are inherently more stable • Duty cycle • Typical value of 95% requires 24 hour hold time/1 hour recycle time • Margin on heat loads • Even with mature design, require 100% margin on loads • Margin is applied to external loads (detector dissipation, wire conduction, etc.) and internal parasitics, NOT to heat flow between stages during recycles • Magnet current limited to 2 amps

  4. Astro-H Heritage • 3-stage ADR capable of operating with 2 heat sinks (1.3 K and 4.5 K) • Designed to mount to the 1.3 K helium tank • Tank is a large heat capacity between stages • Total mass is 14.9 kg

  5. 3-Stage ADR Design • Astro-H configuration • Configuration for this study

  6. Heat Loads • Heat loads proportionally reduced from IXO design by pixel count (~50%) • 0.56 µW at 50 mK 0.28 µW at 45 mK • 7 µW at 0.6 K 3.5 µW at 0.6 K • 55 µW at 1.8 K 28 µW at 1.8 K • 45 mK is a very conservative control temperature • Captures inefficiency due to limited thermal conductance between salt pill and detector, and thermal gradients in the salt pill

  7. ADR Refrigerant Masses • Optimal stage masses are very close to Astro-H design Stage Refrigerant, mass Astro-H refrigerant, mass 1 230 g, CPA (@ 2 T) 270 g, CPA (@ 2 T) 2 130 g, GLF (@ 3 T) 150 g, GLF (@ 3 T) 3 160 g, GLF (@ 3 T) 150 g, GLF (@ 3 T) • Differences in optimal mass can be rebalanced by adjusting hold temperatures Stage Assumed hold T Balanced hold T Modeled value 1 45 mK 45 mK 45 mK 2 0.6 K 0.6 K 0.6 K 3 1.8 K 2.2 K 2.0 K • ADR modeling assumes Kevlar suspension for 1st stage has a heat intercept coming from 2nd stage

  8. ADR Hold Time • 100% margin applied to heat loads • Stage 3 runs out of current at >24 hours • Stage 1 holds for ~36 hours • Stage 1 mass could be reduced without loss of performance

  9. ADR Recycle • Max heat reject rate is 10.6 mW • Stage 3 heat rejection dominates recycle time • Recycle time is 1.6 hours • 94% duty cycle

  10. ADR Controller • ADRC for Astro-H can be used as-is, with simplification of control algorithms • Temperature readout • Magnet power supplies • Control software (FPGA) • Power • Hold time: 29.1 W • Peak: 55 W • All magnets @ 2 A • (Can avoid this condition) • Mass • 13.7 kg

  11. ADRC Capabilities

  12. Summary • ADR technology is mature • Sizing of Astro-H ADR allows design to be used with modest re-configuration • Hold time is limited by upper stages • Can reduce mass some by reducing size of 1st stage, or keep for extra margin • HTS leads for Astro-H are also usable as-is • Long-lead items • GLF refrigerant (from Konoshima Chemical Co. in Japan) • Low risk approach • Cost (Astro-H actuals as of March 2011 plus estimate to finish) • ADR: $3.5M (Includes BBM, ETU, Flight Unit) • ADRC: $8.7M (Includes BBM, EDU, Flight Unit) • Risks • Magnetic shielding: need to refine models and increase shield mass to achieve lower fringing fields than for Astro-H • Design of Kevlar suspension heat intercept for 1st stage

  13. 3-Stage vs 5-Stage ADR • 5-Stage continuous ADR prototype (TRL 4) • Higher duty cycle (100%) • ~1 mW cooling at 1 K • 5-6 µW at 50 mK • Total mass of <10 kg • Low magnetic fields • For current study • From 1 K intermediate stage, heat load at 50 mK is 0.76 µW • CADR mass can be reduced by 2x • Peak heat reject of ~1 mW • Needs further development to reach TRL 6 2 stages cool continuously to ~1 K (~15 minute cycle) Cryocooler heatsink at 4-5 K 3 stages cool continuously to 50 mK (~15 min cycle) 1 K shield (removed for assembly)

  14. Control Electronics for CADR • Based on Astro-H ADRC • Includes temp. monitor and control • Power based on magnet currents and duty cycle Prototype magnet driver

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