Linear free piston combustion engine with indirect work extraction via gas linkage

Various embodiments of the present invention are directed toward a linear free piston combustion engine with indirect work extraction via gas linkage, comprising: a cylinder with two opposed free pistons disposed therein that form a combustion section in a center of the cylinder, each free piston comprising a front face facing the combustion section and a back face facing the opposite direction; two opposed extractor pistons disposed in their own cylinders at opposite ends of the free piston cylinder, each extractor piston comprising a front face facing the combustion section and a back face facing the opposite direction; and two gas linkages, each gas linkage comprising a volume sealed between the back face of a free piston and the front face of an extractor piston; wherein each extractor piston is connected to a rotary electromagnetic machine.