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MASER 4 K closed cycle refrigerator

Submitter: Bert Woestenburg
Description: Note from the editor: This submission is part of our AJDI reftrofit project, in which we endeavour to collect historic pictures and place them at roughly the correct date, often many years ago. You may view them by clicking the Archive button above. Please send us your old pictures, if you stumble across them. Preferably with some information as to time, place, subject and visible people.Thank you. Enjoy.

In order to test and use the 5 GHz MASER in the Dwingeloo telescope, a 4 K closed cycle refrigerator was built in Dwingeloo, based on a similar NRAO design, using a CTI 1020 cooling system for precooling and a Joule-Thomson expansion to cool the He-gas to a 4 K working temperature for the MASER. The pictures show the 4 K cryostat with the heat exchangers between the 20 K cooler stations and the 4 K station, also showing the measured temperature of the 4 K station as a function of heat dissipation. The pictures also show the MASER mounted on top of the 4 K plateau, as well as other electronics at the 20 K station (e.g. an L-band Up-converter) and the 70 K station (with one of the first cryogenic FET-amplifiers).
Copyright: ASTRON
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