A suite of neutron time-of-flight detectors to measure hot-spot motion in direct-drive inertial confinement fusion experiments on OMEGA

Abstract

A suite of six neutron time of flight detectors capable of measuring the primary DT neutron energy spectrum has recently been completed on the OMEGA Laser System. The detectors are positioned along multiple quasi-orthogonal lines of sight (LOS’s) in either a stand-alone, collinear, or antipodal configuration. The collinear detector configuration enables one to measure the neutron velocity along the detector LOS independent of the neutron-production history, while the antipodal detector configuration enables one to directly measure of the hot-spot velocity along the detector axis and Gamow velocity shift due to the plasma ion temperature. Using these six measurements of the primary DT neutron energy spectrum, the neutron-averaged hot-spot velocity and Gamow velocity shift of DT fusion neutrons have been measured in cryogenic experiments on OMEGA for the first time. The detector suite is operable between DT neutron yields of 1 × 1013 to 2 × 1014 with an uncertainty of ∼14 km/s in the neutron-averaged hot-spot velocity measurement.