Fig. 1. Schematic of the SHOTGUN III-U divergent gas-puff Z-pinch device. The distance between the inner and outer electrodes was 30 mm. The gas was puffed from an annular Laval nozzle on the inner electrode.

Fig. 2. Discharge currents (input and load) and soft x-ray signals (SCI and XRD). The peak of the SCI signal is set as the origin of time.

Fig. 3. Gated images of the pinch plasma at (a) −294 ns, (b) −150 ns, (c) −50 ns, (d) 26 ns, (e) 396 ns, and (f) 700 ns. The locations of the electrodes are shown as white lines. The first pinch occurred in front of the inner electrode, and the second pinch occurred in the middle of the two electrodes.

Fig. 4. Radius of the pinch plasma vs time. The contraction velocity was 5.5 × 10⁴ m/s.

Fig. 5. Circuit model for the Z-pinch discharge. Only the inductive part is treated as time-dependent.

Fig. 6. Voltages V and V − RI and inductance L. The inductance increased rapidly at the pinch.

Fig. 7. Input energy, inductive energy, and net input energy. The discharge circuit changes after the pinch.

Fig. 8. Soft x-ray pinhole camera with CCD. A 15 µm Be filter was used for removing soft x-rays with energies less than 1 keV.

Fig. 9. K-shell radiating hot spot image taken with a CCD camera. The inner electrode is indicated by the white dashed line.

Fig. 10. K-shell radiating hot spot image taken with a magnifying CCD camera.