One of the scientific goals of the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory, Livermore CA, is to obtain thermonuclear ignition by compressing 2.2 mm diameter capsules filed with deuterium and tritium to densities approaching 1000 g/cm3 and temperatures in excess of 4 keV. Thefusion reaction d + t → n + a results in a 14.03 MeV neutron providing a source of diagnostic particles to characterize the implosion. The spectrum of neutrons emanating from the assembly may be used to infer the fusion yield, plasma ion temperature, and fuel areal density, all key diagnostic quantities of implosion quality. The neutron time-of-flight (nToF) system co-located along the Neutron Imaging System line-of-site, (NIToF), is a set of 4 scintillation detectors located approximately 27.3 m from the implosion source. Neutron spectral information is inferred using arrival time at the detector. The NIToF system is described below, including the hardware elements, calibration data, analysis methods, and an example of its basic performance characteristics.
The National Ignition Facility (NIF) is a 192-beam high energy laser designed for Inertial Confinement Fusion (ICF),
and High Energy Density (HED) and basic science experiments. In order to achieve ignition with an ICF target, the
beam and target alignment must be performed within very tight specifications. At the same time, in order to be able to
conduct the wide range of HED and basic science experiments, the facility must be able to meet the tight tolerances for
both main and offset backlighter beams and targets. To diagnose the ignition event, many different target diagnostics are
employed, including optical, x-ray, and nuclear diagnostics. These target diagnostics must also be positioned accurately
and reliably within very tight specifications in order to ensure good data is acquired. In this paper, we describe the
strategy for beam, target, and diagnostic alignment at NIF.
Conference Committee Involvement (1)
Target Diagnostics Physics and Engineering for Inertial Confinement Fusion
14 August 2012 | San Diego, California, United States