Electrical Explosion of Flat Conductors in Megagauss Magnetic Fields

Experiments with electrically exploding copper foils of thickness 100 µm and width 5 mm were performed on a MIG generator at a current of amplitude up to 2.5 MA and rise time 100 ns. Using a four-frame optical camera with an exposure time of 3 ns, the intrinsic luminescence of the foil outer surface was imaged. The images showed different stages of plasma generation and instability development, in particular, the formation of a plasma channel along the foil longitudinal axis within about 75 ns from the onset of current flow. The factor of enhancement of the magnetic field at the foil edges was estimated analytically. The estimates have indicated that the magnetic field enhancement may result in the formation of a shock wave propagating from the foil edge to its center.