consists of a long row of doughnut-shaped magnetic induction cells, each connected to a high-voltage generator. There are 74 in total in each accelerator but not all may be used. At the instant of firing, each generator discharges its power, creating a pulse of electric current through its induction cell, which in turn creates a large voltage difference across the gap separating that cell from its neighbor. The electron beam-pulse travels through the central bore of the cells, receiving a 200 keV energy kick each time it passes through a gap. One of the design problems was designing the new induction cores to fit in the confines of the previous facility. The design team had to replace the ferrite used in the first axis cores with "metglas"—paper-thin ribbons of amorphous iron tape. The maximum magnetic field strength (saturation point) in metglas is five times higher than in ferrite. The magnetic tape was insulated by thin layers of mylar and wound up into a roll of 20,000 turns to make mammoth six-foot-diameter cores, each four inches wide and weighing more than one and a half tons. Four cores fit into each induction cell. Perhaps the most significant technical advance achieved at the DARHT facility is the high-speed camera used to image x-rays on the second axis. This camera utilizes the world's largest LSO crystal array to convert the x-rays into visible light which are then imaged with the world's highest speed CCD camera (developed jointly by MIT and Los Alamos) at more than two million frames per second. This scintillation camera is further augmented by a large anti-scatter (“Bucky”) grid to improve image contrast. The unique combination of diagnostics solves technical surveillance problems that have persisted since the Manhattan Project enabling the United States to assert higher confidence in its nuclear stockpile performance and safety margins without the need for nuclear testing. Images References Nuclear weapons infrastructure of the United States Nuclear stockpile stewardship Los Alamos National Laboratory