The Giant Planet Facility

The Giant Planet Facility is an electric-arc-jet facility capable of simulating the heating environment for entry into the atmosphere of Jupiter. The facility produces a testing regime hitherto unavailable in arc-jet plasma facilities. It is rated at 100 MW and operates with a hydrogen-helium gas mixture to produce a stagnation-flow region with simultaneous high radiative and convective heating. The significance of this flow regime is that it permits the measurement of the ablation performance of materials under conditions of massive boundary-layer blowing, thus making it possible to assess the coupling that exists between radiative and convective heating. Such basic measurements are vital to the design of the heat shield for a probe entering the atmosphere of Jupiter. Entry into Jupiter's atmosphere occurs at a relative speed of 48 km/sec, and the resulting severe heating environment is dominated by gas-cap radiation from the shock-heated flow. Preliminary tests have been made in the Giant Planet Facility to establish the degree of simulation that can be obtained and to verify facility design techniques. Total heat-transfer rates of 26 kW/cm2--including a radiative component of 8 kW/cm2-have been measured on blunt test bodies 4 cm in diameter. These high heating rates attained in the facility closely match the rates predicted over most of the heat shield. The extremely high radiative heating at the stagnation point of the heat shield will be within a factor of 2 to 4 of projected facility capabilities. This paper summarizes the design concepts for specifying the arc heater and nozzle system, the hardware development, the calorimetry design for facility calibration and testing, and the operational performance limits of the facility.