For many applications, it is necessary to nearly simultaneously apply heat and gas over an extended area, for example, in the ignition of a mass of propellant or over a surface to accomplish mechanical work. This near simultaneous ignition is best accomplished by a source with a very fast propagating speed, that is, by a stimulus with a propagating velocity characteristic of a detonation, 5000 to 8000 meters per second. For the same applications, however, it is often required that the source of heat and gas which actually performs the function, for example, ignites the propellant or provides a force against a surface, be a "soft" or nondetonating stimulus. Although a detonation might provide adequate heat and gas to accomplish the intended purpose, the accompanying detonation wave cannot be tolerated because of the mechanical impulse applied to the surrounding volume. For example, many commonly used rocket or gun propellants are fashioned into complex geometric shapes termed "grains" in order to control the overall burning rate of the propellant mass. A detonation wave impinging on such grains will shatter the grain structure, thus destroying the physical configuration which is necessarily designed into the grain. What is needed, then, for these types of applications, is a device which is capable of transferring a stimulus over an extended region with a very high speed, but whose outward stimulus at the point of ignition or gas evolution is characteristic of a fast deflagration, without an accompanying shock or detonation wave.