Fig. 4.

Proton radiography. a Normalized number of 15 MeV protons detected on a CR-39 plate. The normalization is such that unity corresponds to the mean number of protons per pixel on the detector. The D³He capsule was imploded at t = 29 ns. Fusion reactions occur 0.6 ns after the start of the implosion and the protons are emitted isotropically within a short burst, of ~150 ps duration³⁹. The flight time of the protons to the plasma is 0.1 ns. The chlorinated plastic foils were driven with a 10 ns long pulse shape (see Fig. 1). X-ray data and FLASH simulations indicate that the plasma flows are close to collision by 29 ns (see also Supplementary Figure 9 in Supplementary Methods). Thus, this proton image can provide an estimate of the initial seed fields. b Same as a, but with the deuterium–tritium capsule imploded at t = 34 ns. The development of structures shows the development of fields in the interaction region. c Same as b, but with the chlorinated plastic foils driven with the 5 ns long pulse, which gives higher flow velocities, and hence higher magnetic Reynolds numbers. d Reconstruction of magnetic fields for case a. e Reconstruction of magnetic fields for case b. f Reconstruction of magnetic fields for case c. g Power spectrum of the magnetic energy from the reconstructed magnetic field from experimental data (the region bound by a dashed line in panel f)