Development of Cryogenic Technologies and Systems for mm and sub mm wave receivers for Ground based Astronomical Applications

This paper presents details of cryogenic system envisaged and being realized for cooling of low noise millimeter (mm) and submillimeter wave receiver front-end components. Cryogenic system for ground based astronomical observation consists of a vacuum enclosure i.e. Cryostat, which will be evacuated using two stage vacuum pumping system, and a closed cycle mechanical cooler to achieve and maintain cryogenic temperature. Cryogenic system will cool the RF front-end components to $\sim 35 \text{K}$ and $\sim 100 \text{K}$, to reduce their thermal noise. This reduction in temperature of front-end components will provide a significant improvement in sensitivity of complete system enabling it to measure CO transitions in Milky Way and nearby galaxies. In addition to reducing the thermal noise, this cryogenic system also offers a very high reliability and stable operating environment for all components placed inside the vacuum enclosure.