X-pinch dynamics: experiment and simulation

Summary form only given. An X-pinch plasma is produced by exploding two 10-50 micron metal wires that cross and touch at a single point (in the form of an X) using a 200-400 kA, 100 ns (FWHM) current pulse. In the region of the original cross point of the wires, a magnetically driven plasma implosion occurs, and one or more <1 ns intense ray bursts are emitted. Although X pinches have been successfully developed as point sources of soft rays for radiography, the physical processes that produce the point source of radiation are not well understood. Using X pinches to make high-resolution ray radiographs of the X pinch implosion process, the formation of 300 /spl mu/m long, /spl sim/100 /spl mu/m diameter z-pinches in the region of the original wire cross point about 2 ns before the characteristic ray bursts occur has been demonstrated. The z-pinches implode to 10 /spl mu/m diameter and then develop gaps in the radiographic images in one or two places coincident in time with intense ray burst(s). Immediately following the moment of ray burst emission, explosive disassembly of the z-pinch occurs on a /spl sim/1 ns time scale, accompanied by the launching of shockwaves into the surrounding material. Using a radiative MHD model, it has been possible to simulate the main characteristics of this process. This model shows all of the dynamic stages just described for the experiments with approximately the correct time for each stage. We present new results that have been obtained using an ray streak camera in different energy ranges with time resolution as good as 10 ps. The simulations yield comparable ray burst durations as a function of energy.