X-Ray Imaging Measurements of Capsule Implosions Driven by a $Z$-Pinch Dynamic Hohlraum

The radiation and shock generated by impact of an annular tungsten $Z$-pinch plasma on a 10-mm diam $5\mathrm{\text{−}}\mathrm{m}\mathrm{g}/\mathrm{c}\mathrm{c}$ $\mathrm{C}{\mathrm{H}}_{\mathrm{2}}$ foam are diagnosed with x-ray imaging and power measurements. The radiative shock was virtually unaffected by $Z$-pinch plasma instabilities. The 5-ns-duration $\sim 135\mathrm{\text{−}}\mathrm{e}\mathrm{V}$ radiation field imploded a 2.1-mm-diam CH capsule. The measured radiation temperature, shock radius, and capsule radius agreed well with computer simulations, indicating understanding of the main features of a $Z$-pinch dynamic-hohlraum-driven capsule implosion.

Figure 1

Dynamic hohlraum schematic diagram. The image of the cylindrically symmetric $\mathrm{C}{\mathrm{H}}_{\mathrm{2}}$ foam and capsule is a preshot x-ray radiograph. The tungsten plasma (striped lines) and foam shock (dashed lines) are illustrations only.

Figure 2

End-on x ray from an experiment with no embedded capsule. Times given in the upper left corner of each image are in ns with respect to the beginning of the drive radiation plateau (see Fig. 3). The 5-mm-diam diagnostic aperture is shown as a dashed circle. Postprocessed simulation images are shown next to the data. The red curves to the right of each image represent a $200\mathrm{\text{−}}\mu \mathrm{m}\mathrm{\text{−}}\mathrm{\text{tall}}$ horizontal lineout through the experimental image and the blue curves are corresponding lineouts through the simulation images.

Figure 3

Time history of the measured radiation temperature at the ZPDH center [$T_r$ $(\exp )$; open triangles], the shock radius [$R_s$ $(\exp )$; red asterisk with error bars], and the capsule radius [$R_c$ $(\exp )$; green diamonds with error bars]. Simulations of the radiation temperature, shock radius, and capsule radius are displayed as dashed, dot-dashed, and solid lines, respectively.

Figure 4

End-on x-ray images from a capsule implosion experiment. Times given in the upper left corner of each image are in ns. The locations of lineouts displayed in Fig. 5 are shown as dotted arrows.

Figure 5

Capsule implosion experiment lineouts. The time and orientation of lineouts (a), (b), and (c) are indicated in Fig. 4. The feature labels “a”, “s”, and “c” correspond to the ablation plasma emission, the shock emission, and the capsule absorption, respectively. The dashed horizontal lines represent the approximate intensity of the thermal radiation corresponding to the temperature displayed in Fig. 3.