We are investigating the dependence of the fiber diameter in POW experiments on the dynamics of the implosion. Recent data from the JEX experiment at Troitsk suggest that the diameter of the fiber plays an important role in the dynamics of the implosion. In general, the smaller fiber diameter permits a more stable implosion possibly due to a higher impedance. High impedance in the fiber forces the current during the initial stages of the implosion to flow preferentially in the outer plasma shell and, thus, prevent the fiber from prematurely exploding. This suggests that there is a maximum diameter fiber that can be used to give a stable core during the compression phase of the implosion. In our experiment, an aluminum plasma jet is created from an exploding foil and then imploded onto a micron sized diameter copper wire (7–50 &mgr;m). In addition, an axial DC magnetic field (Bz0 ≤ 300 G) is applied externally to stabilize the imploding aluminum plasma and to study the interaction of the magnetic field with different diameter wires. We have found in previous experiments that the load configuration can significantly affect the magnetic field required to optimize the implosion. For example, peak x‐ray production for a load consisting of a 25 &mgr;m copper wire occurs at fields of 150 G while the aluminum jet alone is optimized at 50 G. The pinch is driven by a 2 &OHgr;, 0.1 TW generator (250 kA in 80 ns). Diagnostics include filtered PIN XRDs, time‐resolved schlieren photography, and time‐integrated multiple filtered pinholes.