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Strip film and multiple spark schlieren pictures of reflected shocks were taken in the gases He, A, N2, O2, H2, NO, CO2, N2O, CH4, and C3H8. Interaction of the reflected shock with the boundary layer behind the incident shock was observed in all gases except He and A. The bifurcation and acceleration associated with the interaction limits the use of the reflected shock region for high-temperature kinetic and equilibrium studies. It was possible to minimize the effects of this interaction by using gases with high γ and confining measurements to a region near the back wall. Reflected shock observations agreed with Mark's theory of the development of bifurcation but disagreed with his predicted deceleration of the reflected shock. From comparison of incident and reflected shock velocities, measured at the backwall, with ideal one-dimensional theory, it was concluded that calculations of the temperature behind the reflected shock from incident shock velocities would yield high results. Decelerations of the reflected shock in N2 and O2 have been observed in the strip films and were related to the vibrational relaxation behind the reflected shock. Measurements of relaxation times from the film yielded values which are in good agreement with Blackman's data. These experiments indicate that changes in reflected shock velocity can be used to observe the overall reaction rates of fast chemical reactions.

A conventional shock tube modified so as to prevent local early detonation from the diaphragm burst or from wall crevasses was used to study the initiation of detonation behind the reflected shock wave. Three types of initiation behavior were observed, two of which appear to be nicely one dimensional. In all cases stoichiometric hydrogen-oxygen mixtures diluted with argon were used in the tube. In the first case a simple acceleration of the reflected shock occurred when the pressure wave generated by the adiabatic explosion reached the reflected shock. In the second case a typical accelerating wave pattern headed by a shock wave was formed behind the reflected shock while in the third case (which does not appear to be strictly one dimensional) the adiabatic explosion quickly produced a Chapman-Jouguet detonation wave behind the reflected shock wave. A simple qualitative theory for the occurrence of the wave patterns observed is presented and the adiabatic explosion delays are compared to Schott and Kinsey's recent results using a different shock-tube technique.

Laser and radiative ignition of 24 solid propellants and explosives was analyzed. The effect of ignition criterion used to calculate ignition delays from models was evaluated. Values for the optical parameters reflection, R A and absorption, k^ coefficients at wavelengths 0.36-1,1.06 and 10.6 urn were summarized. Effects of in-depth absorption and vaporization were considered. Methods for determining the relation of ignition delays for conductive heating (R x = 1, k A = infinity) and radiative heating at various wavelengths are presented. Methods for deriving kinetic parameters for the ignition and vaporization mechanisms for RDX-based materials were developed. Changes in the ignition mechanism at high radiative flux levels are discussed. A summary of the minimum flux levels needed for ignition and the Arrhenius kinetic parameters determined from ignition delay measurements with several energetic materials is presented. List of Figures viiList of Tables ix IX INTENTIONALLY LEFT BLANK.

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