The magnetic recoil spectrometer for measurements of the absolute neutron spectrum at OMEGA and the NIF.

The neutron spectrum produced by deuterium-tritium (DT) inertial confinement fusion implosions contains a wealth of information about implosion performance including the DT yield, ion-temperature, and areal-density. The Magnetic Recoil Spectrometer (MRS) has been used at both the OMEGA laser facility and the National Ignition Facility (NIF) to measure the absolute neutron spectrum from 3 to 30 MeV at OMEGA and 3 to 36 MeV at the NIF. These measurements have been used to diagnose the performance of cryogenic target implosions to unprecedented accuracy.

Neutron spectrometry--an essential tool for diagnosing implosions at the National Ignition Facility (invited).

DT neutron yield (Y(n)), ion temperature (T(i)), and down-scatter ratio (dsr) determined from measured neutron spectra are essential metrics for diagnosing the performance of inertial confinement fusion (ICF) implosions at the National Ignition Facility (NIF). A suite of neutron-time-of-flight (nTOF) spectrometers and a magnetic recoil spectrometer (MRS) have been implemented in different locations around the NIF target chamber, providing good implosion coverage and the complementarity required for reliable measurements of Y(n), T(i), and dsr. From the measured dsr value, an areal density (ρR) is determined through the relationship ρR(tot) (g∕cm(2)) = (20.

Assembly of high-areal-density deuterium-tritium fuel from indirectly driven cryogenic implosions.

The National Ignition Facility has been used to compress deuterium-tritium to an average areal density of ~1.0±0.1 g cm(-2), which is 67% of the ignition requirement.