A time-resolved measurement of wire Z- pinch K-shell diameter

Summary form only given. An accident of misalignment allowed an axially averaged but fully time-resolved measurement of the diameter of a wire Z-pinch during the K shell emission. Non-optimized aluminum single arrays were used with peak currents of ~6 MA, implosion times of ~250 ns, and K yields of 30 to >70 kJ in ~40 ns pulse widths. By comparing the K-power observed with a direct view of the pinch with K-power observed behind a partially obscuring 3 mm diameter anode post, and assuming a Gaussian radial profile, the time history of pinch diameter can be estimated. Minimum diameter (~3 mm) occurs on the rising edge of the K-power and then slowly increases by factors of >2 as the K-power decays. One partially-obscured sensor, a GaAs PCD heavily filtered to pass only the K continuum, shows even smaller diameters (~2 mm minimum)