Detailed measurements of the time dependence of the neutron flux from the implosion of DT- and/or DD-filled targets are required to better our understanding of inertial confinement fusion. Past efforts at developing fast neutron detectors have generally suffered from a lack of sensitivity and/or insufficient time resolution. In this paper we report on a new streak camera diagnostic for directly time-resolving the neutron burnwidth for ICF implosions. The technique uses the (n,p) reaction in CH₂ to convert the neutron signal to a proton signal, which is proximity coupled to a CsI secondary electron emitter and is subsequently recorded with a standard LLE large-format x-ray streak camera. An x-ray signal is recorded simultaneously with the neutron-produced signal and provides an accurate timing fiducial for burn-time measurements. We have recorded usable signals from the implosion of DT-filled targets producing yields of 3 X 10 ¹⁰ neutrons, with a target to photocathode distance of 30 cm. The calculated time resolution is better than 20 ps for 14 MeV neutrons and 10 ps for 2.45 MeV neutrons. Our technique for recording the neutron flux can also be extended to high-speed framing cameras, currently capable of 35-ps-duration gate times. The framing cameras will permit the simultaneous recording of the burnwidth and the neutron energy spectrum. Also, time-resolved neutron imaging of the core will be possible for DD yields > 10¹².

Date Published: 1 January 1993
PDF: 8 pages
Proc. SPIE 1801, 20th International Congress on High Speed Photography and Photonics, (1 January 1993); doi: 10.1117/12.145827

Published in SPIE Proceedings Vol. 1801:
20th International Congress on High Speed Photography and Photonics
John Marks Dewey; Roberto G. Racca, Editor(s)