Charged-particle spectroscopy is used to assess implosion symmetry in ignition-scale
indirect-drive implosions for the first time. Surrogate D 3 He gas-filled implosions at the
National Ignition Facility produce energetic protons via D+ 3 He fusion that are used to
measure the implosion areal density (ρR) at the shock-bang time. By using protons
produced several hundred ps before the main compression bang, the implosion is
diagnosed in-flight at a convergence ratio of 3–5 just prior to peak velocity. This isolates …

Charged-particle spectroscopy is used to assess implosion symmetry in ignition-scale
indirect-drive implosions for the first time. Surrogate D {sup 3} He gas-filled implosions at the
National Ignition Facility produce energetic protons via D+ {sup 3} He fusion that are used to
measure the implosion areal density (ρR) at the shock-bang time. By using protons
produced several hundred ps before the main compression bang, the implosion is
diagnosed in-flight at a convergence ratio of 3–5 just prior to peak velocity. This isolates …