Design and realization of pure LN₂ supply system for cooling of black body targets to qualify meteorology payloads

Radiometric calibration ofmeteorologicalpayloads like IMAGER and SOUNDER of INSAT-3D is mandatory to evaluate the instrument for its onboard performance at different temperatures.For such calibration, black body targets (BBTs) are required to be maintained at different constant temperatures within the calibration temperature range. During operation of BBTs, supply of pure LN₂ at a constant pressure controlled within 20–25 PSI is essential to control temperature stability and reduce cooling time for each BBTs. simultaneously other subsystems of thermo vacuum chamber needed supply of pure LN₂ in the range of60-80 PSI. To handle this situation, various options were studied and based on the merits of each option, it was concluded to incorporate a phase separator system with its own pressure control system which will serve these competing requirements and provide required immunity to the BBT system from other system fluctuations.