The National Ignition Facility neutron time-of-flight system and its initial performance (invited)

Abstract

The National Ignition Facility (NIF) successfully completed its first inertial confinement fusion (ICF) campaign in 2009. A neutron time-of-flight (nTOF) system was part of the nuclear diagnostics used in this campaign. The nTOF technique has been used for decades on ICF facilities to infer the ion temperature of hot deuterium (D2) and deuterium-tritium (DT) plasmas based on the temporal Doppler broadening of the primary neutron peak. Once calibrated for absolute neutron sensitivity, the nTOF detectors can be used to measure the yield with high accuracy. The NIF nTOF system is designed to measure neutron yield and ion temperature over 11 orders of magnitude (from 10 8 to 1019), neutron bang time in DT implosions between 1012 and 1016, and to infer areal density for DT yields above 1012. During the 2009 campaign, the three most sensitive neutron time-of-flight detectors were installed and used to measure the primary neutron yield and ion temperature from 25 high-convergence implosions using D2 fuel. The OMEGA yield calibration of these detectors was successfully transferred to the NIF. © 2010 American Institute of Physics.