RADAR INTERFERENCE EFFECTS IN THE LEM DESCENT ENGINE EXHAUST PLUME. PART I. CHEMI-IONIZATION IN THE LEM PROPELLANT SYSTEM. PART II. PREDICTION OF REFRACTION AND ATTENUATION OF THE LEM RADAR BEAMS.
Abstract
An experimental program was undertaken to determine the importance of chemi-ionization as an electron-contributing mechanism in the LEM descent engine propellant system. Studies were conducted on UDMH/N2O4 diffusion flames at low pressures (5 to 50 Torr) using Langmuir probes and mass spectrometric procedures. These flames were also examined using Langmuir probes at atmospheric pressure and at the descent engine chamber pressure (110 psia). The actual fuel, Aerozine 50/N2O4, was tested at the latter pressure only, under conditions directly analogous to those in the chamber. It was concluded as a result of this experimental investigation that thermal ionization will be, by far, the dominant electronproducing process in the LEM combustion chamber. The refraction and attenuation of two radar beams passing through the LEM exhaust plume are predicted. The maximum beam refraction is predicted to be about 2 milliradians for the doppler beam passing through the most dense part of the plasma. The altimeter beam experiences a maximum refraction of just over 1 milliradian. The attenuation (absorption) of both beams was found to be less than 0.1 db, which is probably well within the allowable signal-to-noise margin for the LEM radars. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1965
- Accession Number
- AD0624581
Entities
People
- H. S. Pergament
- W. J. Miller