Magnetic compression of an aluminum vapor cylinder

The magnetic compression of a 3-mm-diameter aluminum vapor jet produced by foil explosion has been studied. The jet is compressed by the current of GAEL, a 2-Ω, 0.1-TW machine. The plasma is diagnosed by a double-pinhole (100-μm) camera, with one pinhole filtered by 10 μm of berylium and the other by 800 angstrom of aluminum on a 6-μm Kimfol substrate. An optical streak camera shows the radial compression as a function of time. A Mach-Zehnder interferometer, operated with a dye laser at 580 nm, is synchronized with the discharge to give the aluminum plasma density at different times. Filtered X-ray diffraction (XRD) gives the time variation of the radiation, and the XRD signal can be correlated with the pinhole pictures. Density measurements at maximum current show small radial compression of the jet, but the structure of the fringes suggests density inhomogeneities along the z-axis of the column. X-ray pinhole pictures are compatible with 1-keV radiation, which corresponds to a temperature between 200 and 500 eV.