Vacuum Ultraviolet Radiation in the Expansion Tube
Abstract
The findings are presented of an optical survey of vacuum ultraviolet (VUV) radiation emitted from the shock layer of a 1-1/2 in. diameter sphere in hypersonic flows of air, argon, nitrogen and argon-nitrogen mixtures. Free stream velocities of 17,000-20,000 ft/sec and densities corresponding to altitudes of about 90,000 ft. were obtained in the BRL expansion tube facility; steady flow conditions prevailed over the model for about 75 microsec. The radiation was recorded on sensitized film down to a lower limit of 1100A. The purpose of the survey was to explore the feasibility of using this facility to measure time and space resolved radiation of the nonequilibrium, vibrationally- excited N2 in the shock layer; part of this radiation is conjectured to ionize O2 ahead of the shock around a hypersonic vehicle, thus enhancing its radar signature. Methods and problems of measuring VUV from this shock layer are discussed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1972
- Accession Number
- AD0757150
Entities
People
- Fritz H. Oertel Jr.
Organizations
- Ballistic Research Laboratory