Measuring Implosion Symmetry and Core Conditions in the National Ignition Facility

Abstract

Tertiary protons with birth energies from 27 to 30.8 MeV result from the implosion of ignition-scale inertial confinement fusion targets, such as those planned for the National Ignition Facility. Measurement of the tertiaries' slowing can provide a determination of the imploded areal density of the fuel capsule, as well as information about implosion asymmetry that results from anisotropy of the areal density and plasma temperature. To determine the utility of tertiaries for all phases of ignition experiments, we analyze three representative cases: a gas capsule (0.7 kJ yield), a cryogenic fuel capsule that fails to ignite (15 kJ), and a cryogenic fuel capsule that ignites and burns (13 000 kJ). In each case, tertiaries escape from the capsule and convey critical information about implosion dynamics.