Abstract: A dry-process corn popper or like heat-expansion device for cereal grains, of the kind comprising a horizontally oriented metal mesh expansion cylinder which is charged with grain; the cylinder is rotated in one direction while being heated to expand the grain, the grain being discharged upon expansion, and the cylinder is subsequently rotated in the opposite direction to discharge incompletely expanded grain and other waste from the bottom of the cylinder. An electrically-powered heat source, producing radiant heat energy, is positioned near the side of the cylinder, away from the waste discharge location; a reflector directs the radiant heat onto and into the rotating cylinder to heat the grain and expand it.