Figure 1

Experimental setup. The mesh was $60\mathrm{\text{−}}\mu \mathrm{m}$–thick Ni with $75\mathrm{\text{−}}\mu \mathrm{m}$ holes separated by $75\mathrm{\text{−}}\mu \mathrm{m}$ wires. Distances were $a=1.5\mathrm{cm}$, $A=30\mathrm{cm}$, and $\mathrm{\text{backlighter}}\mathrm{\text{−}}\mathrm{\text{to}}\mathrm{\text{−}}\mathrm{\text{mesh}}=1.3\mathrm{cm}$. The measured backlighter spectrum is typical (separate images can be made with both types of protons, but only ${\mathrm{D}}^3\mathrm{He}$ protons are used here).Reuse & Permissions

Figure 2

Radiographs generated when four (A) or two (B) laser beams were incident on a CH foil. In (A), interbubble interactions were minimal while the laser was on ($<1\mathrm{ns}$) but significant later. At 1.24 and 1.72 ns, asymmetric bubble structure [18] is superposed on a static background pattern that is still visible at 2.35 ns, after most of the bubble structure has dissipated; the pattern is from fields around the burn-through hole (Fig. 3). In (B), the bubbles have interacted and reconnection has occurred by 0.67 ns. By 1.42 ns, most fields in the intersection region have reconnected (remaining distortion is largely due to burn-through holes).Reuse & Permissions

Figure 3

Distributions of $n_e$, $T_e$, and $B$-field amplitude in an isolated plasma bubble generated by a laser beam incident from the right, simulated with the 2D code LASNEX [24]. The laser beam is equivalent to each beam in the 4-beam experiment. The foil is at $Z=0$. The field is perpendicular to the image plane. While the laser is on, the $B$ field is localized on the surface of the quasihemispherical bubble (c1). A strong field structure appears at the edge of the hole burned into the foil some time after the laser is off (c2).Reuse & Permissions

Figure 4

Radiography images were used to deduce maps of the $B$ field at the foil. In (a1),(a2), from Figs. 2a, 2b, the location of each beamlet can be compared with the location it would have had with no $B$ fields (beamlets on the image edges define the grid of “undeflected” locations); (b1),(b2) show displacement vectors $\xi$. Arrays of displacement amplitudes are shown as images [(c1),(c2)]; each pixel represents one beamlet, with value proportional to displacement. Displacement is proportional to $\int \mathbf{B}\times d\mathit{l}$ along the particle trajectory, so lineouts of (c1),(c2) (along the red arrows) provide quantitative measurements of $|\int \mathbf{B}\times d\mathit{l}|$ at the foil location [(d1),(d2)].Reuse & Permissions