RESEARCH OF AERODYNAMIC METHODS OF PRODUCING ANTENNA WINDOWS IN A PLASMA SHEATH
Scientific rept. no. 1, 14 Oct 1963-19 Oct 1964
MITHRAS CAMBRIDGE MA
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Two aerodynamic methods of creating transmission windows in typical plasma sheaths surrounding re-entry vehicles have been investigated 1 the use of jets of coolant from flush nozzles which penetrate across the plasma slab and then mix with the ionized gases as they are carried downstream, 2 the use of a physical flow diverter to bypass some of the ionized flow laterally around the antenna. Equations are developed for the lateral jet penetration in a supersonic stream and for one-dimensional mixing for both perfect gases and real gases in thermodynamic equilibrium. The assumption of real-air equilibrium thermodynamics yields coolant requirements considerably below the perfect gas values for the jet injection method. It is concluded that the jet injection method will reduce a 200 mc. signal attenuation to 3 db. with modest jet flow rates of helium on a typical re-entry trajectory. Conversely, the use of a physical flow diverter is not an effective method of creating a transmission window where the ionization layer is not adjacent to the vehicle surface or where the attenuation needs to be reduced more than 10 db.
- Guided Missile Reentry Vehicles