Operational S-Band Traveling-Wave Maser System in 15/spl deg/k Closed-Cycle Refrigerator

The design of practical traveling-wave masers has, in the past, been limited to physical temperatures in the range of liquid helium (≤ 5°K). The advantages of TWM operation at such low temperatures are manifold. All of the important operating characteristics of a TWM such as gain, instantaneous bandwidth, tuning bandwidth, effective noise temperature, etc. improve as the physical temperature is lowered. The consequence of such operation has been a sophisticated, large, and costly cryogenic system to provide the necessary environment.