Herrmann H W, Kim Y H, Zylstra A B, Geppert-Kleinrath H, Meaney K D, Young C S, Lopez F E, Fatherley V E, Pederson B J, Oertel J A, Hernandez J E, Carrera J, Khater H, Rubery M S, Horsfield C J, Gales S, Leatherland A, Hilsabeck T, Kilkenny J D, Malone R M, Batha S H
Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
Rev Sci Instrum. 2018 Oct;89(10):10I148. doi: 10.1063/1.5039378.
Fusion reaction history and ablator areal density measurements for Inertial Confinement Fusion experiments at the National Ignition Facility are currently conducted using the Gamma Reaction History diagnostic (GRH_6m). Future Gas Cherenkov Detectors (GCDs) will ultimately provide ∼100x more sensitivity, reduce the effective temporal response from ∼100 to ∼10 ps, and lower the energy threshold from 2.9 to 1.8 MeV, relative to GRH_6m. The first phase toward next generation GCDs consisted of inserting the existing coaxial GCD-3 detector into a reentrant well which puts it within 4 m of the implosion. Reaction history and ablator gamma measurement results from this Phase I are discussed here. These results demonstrate viability for the follow-on Phases of (II) the use of a revolutionary new pulse-dilation photomultiplier tube to improve the effective measurement bandwidth by >10x relative to current PMT technology; and (III) the design of a NIF-specific "Super" GCD which will be informed by the assessment of the radiation background environment within the well described here.
