The Z machine origins can be traced from the Department of Energy need to replicate in a lab environment the fusion reactions of a thermonuclear bomb, to better understand the physics involved. Since the 1970s the DoE had been looking into ways to generate electricity from fusion reactions, with continuous reactions such as Tokamaks or discrete fusion of small balls of light atoms. Since at the time lasers were far from having the required power, the main approach considered was heavy ion fusion. However major advances such as Q-switching and Mode-locking made lasers an option (culminating into the National Ignition Facility) and the Heavy Ion Fusion programs became more or less dormant. In 1985 the review of DoE's program by the National Academies stated "The energy crisis is dormant for