Structure and emission of a stratified pulsed discharge

A 20-channel apparatus for optical and electrical plasma diagnostics is used to study the geometric structure and evolution of a stratified pulsed discharge with a current of 100,000 or 1 million A and a half-period of 9 or 45 microsec. A cylindrical discharge with an initial diameter 6 or 18 cm is formed by the electrical explosion in air of an aluminum foil 5 microns thick. There are three characteristic stages in the time evolution of the emission from the discharge: the starting stage, the high-temperature stage, and the afterglow. Two layers of radiating plasma form in a stratified pulsed discharge. These layers are separated by an opaque layer consisting of the finely dispersed remnants of the exploded foil. The outer and inner plasma layers are at different temperatures and exhibit different brightness. The discharge becomes radially asymmetric as the magnetic field acts on the parallel discharge layers. It is concluded that stratified pulsed discharges can be used to develop several controllable light sources with variable spectral brightness, variable light pulse, and a variable emission asymmetry.