The MagPTOF Diagnostic for Bang-time Measurements and Charged-particle Spectroscopy at the NIF

Hong Sio, Massachusetts Institute of Technology

A magnetic particle-time-of-flight (MagPTOF) diagnostic has been designed for measurements of both shock- and compression-bang time at the National Ignition Facility (NIF). This type of measurement, combined with the measured shock-burn weighted ρR, will be used to understand in-flight ρR asymmetries, shock convergence, and implosion dynamics. The MagPTOF design is an upgrade to the existing particle time-of-flight (pTOF) diagnostic, which has recorded accurate shock- and compression-bang times in near-vacuum hohlraum 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 robust measurements of shock- and compression-bang time in gas-filled hohlraum implosions. In addition, MagPTOF can also be fielded as a spectrometer, in which charge particles are energy-dispersed by the magnet and recorded by the CR39 nuclear track detector surrounding the CVD bang-time detector. This capability is especially useful in implosions with low ρR in which charged fusion products can escape. This new capability will allow accurate studies of the T-T alpha spectrum and the 3He-3He and T-3He proton spectra, which are either relevant to stellar nucleosynthesis or Big Bang Nucleosynthesis. The use of the MagPTOF in support of the inertial confinement fusion program and upcoming NIF discovery science experiments will be discussed.

Abstract Author(s): H. Sio, H.G. Rinderknecht, J.A. Frenje, A.B. Zylstra, M. Gatu Johnson, F.H. Seguin, C.K. Li, R.D. Petrasso, J.R. Rygg, S. Ayers, M. Bedzyk, J. Magoon, M. Shoup, C. Sangster, J. Kilkenny