If a supersonic heat wave is overtaken by a shock, either generated externally or'induced by the sudden cooling of the wave front, an overdriven heat wave is formed which is similar to an overdriven detonation. The Mach number of the overdrlven heat wave is proportional to the product of the Mach numbers of the pursuing shock and the heat wave.

Dcparrtnet~r of P/IJ..Y~L..Y, U t~i u~r~i t y of Briri.rh Colutnbia. Vat~couoer, Brilisk Columbia Received February 2, 1972Strong shock waves have been generated in a diaphragm shock tube using an imploding detonation driver of conical geometry. In comparing the performance of the conical driver to a Chapman-Jouguet detonation driver we have found that the conical driver provides comparable Mach numbers at considerably smaller ratios of driver to test gas filling pressures. For example Mach 10 was reached at a pressure ratio of 25 in the conical driver while a ratio of 100 is required to produce Mach I0 in a Chapman-Jouguet driver. In theory the Mach number available from a conical driver is expected to increase without bounds as the ratio of driver cone base to test tube diameter. A simplified model for this scaling is discussed and compared with experimental data. In addition an investigation of Mach number and shock attenuation versus cone slant angle is carried out in order to optimize the driver geometry.Des ondes de choc intenses ont tte generees dans un tube de choc a diaphragme en utilisant un detonateur i implosion de geometrie conique. En comparant le fonctionnement de ce detonateur conique avec celui du dispositif de Chapman-Jouguet nous avons trouve que le detonateur conique fournit des nombres de Mach comparables pour des rapports de pressions beaucoup plus faibles. Par exemple on a obtenu Mach 10 avec un rapport de 25 alors qu'un rapport de 100 etait nkcessaire pour produire Mach 10 dans le dispositif de Chapman-Jouguet. En theorie on prevoit que le nombre de Mach accessible avec le detonateur conique augmente sans limite avec le rapport de la base du c8ne au diametre du tube a essai. Un modele simplifie pour etablir cette proposition est discute et compare aux donnees experimentales. De plus on a effectue une investigation du nombre de Mach et de I'attenuation de I'onde de choc en fonction de I'angle d'obliquite du c8ne, dans le but d'optimiser la geometrie du systeme.

The one dimensional equations governing shock propagation into inhomogeneous media have been developed to allow a shock to be used as a probe. Shock waves which collide with unknown gas or plasma flow fields suffer a change in velocity. Pressure, density, particle velocity, and local energy input at the edge of an unknown flow can be determined from the measurement of unknown flow. The steady variation of the velocity of strong probing shocks reveals details of the local velocity and density distributions inside the unknown flow field. One further result is the extension of the general theory of shock propagation into inhomogeneous media to cover the case when an energy source term appears at the front.Les Cquations unidimensionnelles gouvernant la propagation d'une onde de choc dans un milieu inhomogene ont Ct C dCveloppCes afin de pouvoir utiliser une telle onde en guise de sonde. Les ondes de chocs qui heurtent un gaz inconnu ou des champs d'Ccoulement de plasma subissent un changement de vitesse. La densite de pression, la vitesse des particules et I'Cchange local d'Cnergie en bordure de I'Ccoulement inconnu peuvent Etre determinks 2 partir de mesures de I'Ccoulement inconnu. La variation continue de la vitesse des chocs les plus intenses utilisCs comme sonde rCvele les details de la vitesse locale et des distributions de densite a I'intCrieur du champ d'koulement inconnu. Comme rksultat supplCmentaire on traite de I'extension de la thCorie gCnCrale de la propagation de I'onde de choc dans un milieu inhomogene au cas oh une source dlCnergie apparait sur le front d'onde.

Pressure and temperature gradients across a bow shock in a (partially) ionized gas induce an electrical potential that can be used to drive a current. The voltage difference between electrodes (probes) mounted upstream and downstream of the shock depends on the shock strength (flow Mach number and oblique shock angle) and on the difference of the electrode work functions. Such a bow shock generator has an internal resistance that is governed by the electron temperature and the ion current density at the colder (upstream) electrode. The bow shock generator voltage (typically one volt) was measured as a function of the extracted current (up to 0.8 A/cm2) for different shock angles and flow Mach numbers. A theoretical model that agrees well with these experiments has been developed.

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