A shock wave applicator includes a reflector and a movable shockwave-generating electrode disposed in the reflector at a first focal point. The reflector is at least a portion of an ellipsoidal shape having a long and small axis with the first focal point and a second focal point on the long axis, and the reflector terminates at an edge defining a membrane-covered aperture on a plane intersecting the small axis and coincident with the second focal point.