Report on Alternative Driver Condition Studies

Abstract

An empirical/theoretical study of safe operating conditions of the HEG has been performed. In order to prepare for operating the facility with a driver gas other than pure Helium. The resulting enthalpies and densities in the flowfield have been predicted and tabulated. It is predicted that the HEG can be operated safely also when specific reservoir enthalpies of down to 10 MJ/kg, correspondingto equivalent flight of v infinity &#61 4.5 km/s are required. All conditions are predicted at tailored interface mode, i.e. the reservoir conditions are expected to stay constant during the useful test time of approximately 1-2 ms. For enthalpies higher than 20 MJ/kg, only the undertailored operating conditions have been found as 'safe operating conditions' so far. After further confirmation of the modelling through tests at various enthalpies and reservoir conditions, further attempt to find safe tailored conditions at, say 25 MJ/kg initially, will be attempted.