Monroe effect

The Monroe effect refers to the characteristics of the detonation of a volume of explosive around a hollow or void, a shaped charge. Explosive energy is released directly away from (normal to) the surface of an explosive, so shaping the explosive will concentrate the explosive energy in the void. If the void is properly shaped (usually conically), a high-velocity jet of plasma will form.

In military applications, a Monroe-effect shaped-charge warhead can be expected to penetrate armor equal to 150-250% of the warhead diameter.

Compare to the Misznay-Schardin effect.