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Automated Closed-Cycle Cooling to 250 mK for the Polatron

Bhatia, R. S. and Hristov, V. V. and Keating, B. C. and Lange, A. E. and Mason, P. V. and Philhour, B. J. and Sirbi, G. and Yoon, K. W. and Chase, S. T. (2003) Automated Closed-Cycle Cooling to 250 mK for the Polatron. In: Cryocoolers 12. Springer , Boston, MA, pp. 651-660. ISBN 978-0-306-47714-0.

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We have integrated a 4 K mechanical cryocooler with a helium sorption refrigerator to achieve closed-cycle cooling to a base temperature of 239 mK. The cryocooler consists of two Gifford-McMahon stages which pre-cool a Joule-Thomson expansion stage to below the inversion temperature of ⁴He This in turn provides cooling to below the 5.2 K critical temperature of ⁴He The first two stages of the sorption cooler consist of a ⁴He and a ³He refrigerator, with the ⁴He providing cooling to below the 3.3 K critical temperature of ³He This subassembly buffers the heatload on the final ³He refrigerator. We achieve an operating temperature of 250 mK at the expected 0.5μW heat input from parasitic conduction plus the optical load. The duty cycle of the sorption cooler is 83 %. The sorption cooler is automatically cycled using digitally commanded power supplies. The system will allow for unattended cooldown from 300 K to 250 mK for cooling of the detectors on the Polatron, a ground-based receiver which will be fielded at the 5.5 metre telescope at the Owens Valley Radio Observatory.

Item Type:Book Section
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Mason, P. V.0000-0002-7963-7420
Additional Information:© 2003 Kluwer Academic Publishers. This work was partly supported by NASA Innovative Research Grant NAG5-3465 and NASA NAG5-6573 for US involvement in Planck. The construction of the Polatron is funded by a Caltech/JPL President’s Fund Grant PF-414, NASA Grant NAG5-6573 and NSF Grant AST-9900868. We thank Kathy Deniston for administrative support.
Funding AgencyGrant Number
Caltech/JPL President's FundPF-414
Subject Keywords:Cosmic Microwave Background; Liquid Cryogen; Condensation Point; Pulse Tube Cooler; Heat Switch
Record Number:CaltechAUTHORS:20200114-153649323
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100725
Deposited By: Tony Diaz
Deposited On:15 Jan 2020 00:31
Last Modified:15 Jan 2020 00:31

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