An electromagnetic exciter includes a magnetic circuit device composed of an outer yoke, a flat magnet arranged within the outer yoke, and an inner yoke mounted on the magnet, and a casing within which the magnetic circuit device is contained. The two strands are preferably guided over deflection rollers in such a way that the overlays of the two strands on the already-wound stack are offset from one another by a predetermined angular amount. Product attribute data representing attributes for at least the two products are also received. By aligning through-holes of end plates, separator, and fuel electrode seals with each other and by allowing a stack fastening component to penetrate through the through-holes, the whole is pressed and urged to be assembled. In addition, a lower electrode is disposed on the lower side in order to extend the length of a generated plasma. The opening is located in the rear space such that the accommodation space is not exposed to the outside of the main body.