Maser Dewar for System Operation

Abstract

When in 1866 Sir James Dewar first invented the glass Vacuum container, little did he realize that some hundred years later stainless steel units would be used for system operation. The dewar shown in Fig. 1 was designed to be mounted in the Haystack Antenna located at Tyngsboro, Massachusetts and operated by the Massachusetts Institute of Technology, Lincoln Laboratory.* The cassegrainian antenna is a 120-ft diameter primary reflector and a 9.3-ft secondary reflector. This dewar provides the cryogenic environment required by a maser amplifier and superconducting magnet. The maser and dewar are mounted at +45° when the antenna is looking at the horizon and as the antenna moves to the zenith, they tilt through 90° to the -45° position. Minimum running time required is eight hours. To meet the requirements, a unique nitrogen shielded, high vacuum insulated helium dewar was designed.