Mach Waves in Shock Wave Systems from Detonating Explosives

We have recently obtained many photographs of Mach waves1, known alternatively as ‘bridge’ or ‘Y’ waves2, in the shock wave systems resulting from the detonation of unconfined charges of solid explosive. Waves of this type, which Mach postulated from the observation of soot patterns, are produced when supersonic waves intersect at obtuse angles of incidence. Instead of the simple intersection (which obtains in collisions at acute angles as well as in collisions of sonic waves at any angle of incidence), there is formed a Mach wave which travels in a direction parallel to the plane of symmetry bisecting the angle between the original colliding shock waves.