Simulation of Reentry Vehicle Laser Communications in an 8000-Kilowatt Plasma Facility
Abstract
Laser communications have been proposed as one way to solve the 'radio blackout' problem during the reentry of a manned vehicle. The U. S. Army Missile Command 8000-Kilowatt Plasma Facility was used in a set of experiments to simulate the conditions expected during the reentry of a high-speed vehicle. This experimental study was designed to simulate a typical theoretical Apollo test vehicle reentry trajectory. No plasma effects on the transmitted laser beam were expected or observed. The high temperature gradients and anticipated gas density variations in the flow field were thought to be potential sources of local index-of-refraction fluctuations. By variation of the plasma facility parameters to lower the enthalpy, the Reynolds number, or both, a satisfactory simulation of conditions just before the termination of 'radio blackout' was obtained. The region of the 'reentry corridor' simulated in this investigation is near a 60-kilometer per second velocity. A 0.09-meter diameter flat disk model oriented normal to the flow field was used in experiments to determine the degradation of an He-Ne laser beam modulated by a 20-kilohertz signal on a 40- megahertz carrier. Harmonic analysis of the modulation showed a small modification of the signal. A flat plate 1 meter long was also used in experiments to determine beam deflection by the flow field due to index of refraction fluctuations. Beam deflection was < 0.00001 radians.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1968
- Accession Number
- AD0856535
Entities
People
- Charles Cason
- T. A. Barr Jr.