PURPOSE: To raise magnetic field in the gap to increase an electromotive force without enlarging a magnetic apparatus by connecting in parallel both ends of a coil with electrode pairs provided in the preceding stage and connecting a current lead to the electrode pair in the final stage.

CONSTITUTION: When a triggering device 4 is operated, an explosive 3 starts to explode from the left end side and a gas space 2 is crushed from the left side to form the flow of plasma 5 at a higher velocity. The plasma enters the gap portion 9 between the electrode pair 6A, 6B at an aperture 1A of a liner 1. But, since the directions of plasma flow 5 and magnetic flux are crossed at the right angle, a power E1 is generated between the electrode pair 6A, 6B, a magnetic flux 1 is formed within the gap portion 91 since a current I1 flows into a coil 30 and these magnetic fluxes are mutually superposed to enhance the magnetic field within the gap portion 91. Moreover, when flow of plasma 5 enters the gap portion 91 with passage of time, since the plasma crosses the magnetic fluxes , 1 at the right angle, an electromotive force E2 is generated between the electrode pair 61A, 61B to output a current I2 to a load 8. Since the electromotive force E2 is larger than E1, the electromotive force can be increased without enlarging a magnetic apparatus.