l.C Neutron Streak- and Framing-Camera Diagnostics for ICF Implosions

High-fidelity, time-resolved measurements of the neutron flux from the implosion of DTandlor DD-filled capsules have been a challenging problem for the international inertial-confinement-fusion (ICF) community. A measure of the neutron production rate can provide valuable information on the quaIity of the implosion, such as the confinement time of the plasma. A time-resolving neutron detector is generally used to measure the neutron-production rate since the neutron is the fusion product most likely to escape the burn region and the target without further interaction, thus preserving temporal information. The neutron energies are 14.1 MeV and 2.45 MeV for DT and DD fusion reactions, respectively, and typical fusion burnwidths are in the range of 100-300 ps. In this article we report on a new streak-camera diagnostic for directly time-resolving the neutron burnwidth for ICF implosions. The technique uses elastic scattering of the neutrons in CH2 to convert the neutron signal to a recoil-proton signal, which is proximity coupled toaCsl secondary electron emitter and is subsequent1 y recorded with a standard LLE large-format, x-ray streak camera. Baseline requirements for the neutron detector include the following: directly measured time resolution better than 20 ps; should be positionable to less than 5 cm from the capsule tominimize the transittime spreadcaused by the velocity distribution of the neutrons (this depends on the neutron source temperature); incorporate an optical or x-ray timing fiducial to establish burn time to within f 20 ps; should be capable of recording on the same shot the time histories of both the primary DD and the secondary DT neutrons (the secondarylprimary yield ratio is typically 1 %). Further, the instrument needs to be shielded from the background of y rays. and thermalized and inelastically scattered neutrons originating from nearby diagnostics and the target chamber itself.