Time-resolved Nuclear Diagnostics for Probing Implosion Dynamics and Kinetic & Multi-ion Effects on OMEGA and the NIF
Massachusetts Institute of Technology
On the National Ignition Facility (NIF), a magnetic particle-time-of-flight (magPTOF) diagnostic has been designed for measurements of both shock- and compression-bang times. This type of measurement, combined with the measured areal density (ρR) measured along different lines of sight, will be used to assess evolution of ρR and ρR asymmetries from shock to compression. The magPTOF design is an upgrade to the existing particle time-of-flight (pTOF) diagnostic, which has recorded accurate bang times in cryogenic DT implosions, DT exploding pushers and D3He implosions with accuracy better than 70 ps. The inclusion of a deflecting magnet will increase proton signal-to-background by a factor of 1,000, allowing for measurements of shock- and compression-bang times in D3He-filled surrogate implosions using about 10 MeV shock D3He protons and 2.45 MeV compression DD-neutrons, respectively.
On OMEGA, the Particle X-ray Temporal Diagnostic (PXTD) has been developed for simultaneous time-resolved measurements of several nuclear reactions and X-ray core continuum produced in high energy density plasmas and inertial confinement fusion implosions. Using PXTD removes systematic timing uncertainties typically observed between different diagnostic measurements of nuclear burn histories and X-ray production history. This enables, for the first time, accurate measurements of the X-ray bang time, nuclear-bang times, their time difference, and measurements of Ti(t) and Te(t), from which a quantitative assessment of multiple-ion-fluid effects, kinetic effects during the shock-burn phase, and i-e equilibration rates is made.