Accession Number : AD0427971


Title :   EVIDENCE FOR THE EXISTENCE OF N- FROM THE CONTINUUM RADIATION FROM SHOCK WAVES


Descriptive Note : Research note


Corporate Author : AVCO EVERETT RESEARCH LAB INC EVERETT MA


Personal Author(s) : Allen, R A ; Textoris, A


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/427971.pdf


Report Date : Oct 1963


Pagination or Media Count : 31


Abstract : This work represents a study of the continuum radiation from shock- heated air and nitrogen as a function of density and temperature. For air or nitrogen in which the molecules are completely dissociated yet only partially ionized, radiation produced by the interaction of electrons with neutral atoms will have a stronger density dependence than the radiation produced by electron interaction with positive ions. Intensity measurements of the continuum at 5000 A were made on the equilibrium region behind incident air and nitrogen shocks in the 9 to 11 Mm/micro sec range at initial pressures of from 0.1 mm Hg to 1.0 mm Hg. At higher densities, enhanced radiation is observed which can be attributed to the interaction of free electrons with neutral nitrogen atoms. Strong evidence suggests that this radiation is produced by the capture of electrons by nitrogen atoms in the (2D) state. A photoabsorption cross section of 2.6 x 10 to the minus 16th power sq cm for the N-(D) atom at 5000 A is deduced from the measurements. Besides indicating that a strong Ncontinuum exists, these new measurements of Kramers' radiation also indicate that the positive ion radiation contributes less than previously expected and supports the theoretical calculations of Biberman and Norman for the N+ free-bound radiation.


Descriptors :   *SHOCK WAVES , ABSORPTION SPECTRA , AERODYNAMIC HEATING , AIR , ATMOSPHERE ENTRY , DENSITY , DISSOCIATION , ELECTRON CAPTURE , IONS , MEASUREMENT , NITROGEN , PHOTOMETERS , TEMPERATURE , THERMAL RADIATION


Subject Categories : Acoustics


Distribution Statement : APPROVED FOR PUBLIC RELEASE