When high intensity (≥1019 W cm−2) laser light interacts with matter, multi-MeV electrons are produced. These electrons can be utilized to generate a MeV bremsstrahlung x-ray emission spectrum as they propagate into a high-Z solid target positioned behind the interaction area. The short duration (<10 ps) and the small diameter (<500 μm) of the x-ray pulse combined with the MeV x-ray spectrum offers an interesting alternative to conventional bremsstrahlung x-ray sources based on an electron accelerator used to radiograph dense, rapidly moving objects. In experiments at the Omega EP laser, a multi-MeV x-ray source is characterized consistently with number of independent diagnostics. An unfiltered x-ray dose of approximately 2 rad in air at 1 m and a source diameter of less than 350 μm are inferred. Radiography of a complex and high area density (up to 61 g/cm2) object is then performed with few hundred microns spatial resolution.
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 (D(2)) 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 10(19)), neutron bang time in DT implosions between 10(12) and 10(16), and to infer areal density for DT yields above 10(12). 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 D(2) fuel. The OMEGA yield calibration of these detectors was successfully transferred to the NIF.
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