Accession Number : AD0686458

Title :   PROPOSED METHOD OF MEASUREMENT OF ELECTRON DENSITY IN RE-ENTRY SHEATHS BY OBSERVATION OF ELECTROACOUSTIC RESONANCES,

Corporate Author : SPERRY RAND RESEARCH CENTER SUDBURY MASS

Personal Author(s) : Lustig,Claude D. ; McBee,Warren D.

Report Date : FEB 1969

Pagination or Media Count : 26

Abstract : A method is proposed for measuring the electron density in a re-entry sheath plasma by exciting electroacoustic waves. The waves are launched from an antenna mounted flush with the vehicle skin, and are reflected at a surface in the plasma where the local plasma frequency equals the wave frequency. By analogy with laboratory experiments, standing waves can be set up between this surface and the vehicle skin, causing a resonant decrease in the power reflected at the antenna. For this condition, the electron density gradient close to the vehicle skin can be calculated. The re-entry sheath parameters for blunted cone and slender cone vehicles are examined to determine the applicability of the method. The blunted cone re-entry sheath appears to be ideal for the observation of the resonances. For a slender-cone, the method is less appropriate because the electron density does not, in general, reach a suitable value until relatively low altitudes, where the electron collision frequency has become prohibitively high. (Author)

Descriptors :   (*REENTRY VEHICLES, *PLASMA SHEATHS), ELECTRON DENSITY, ATMOSPHERE ENTRY, BLUNT BODIES, CONICAL BODIES, GUIDED MISSILE ANTENNAS, RESONANCE

Subject Categories : Guided Missiles
      Plasma Physics and Magnetohydrodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE