Meeting Flash Neutron Radiography Requirements with the MegaJoule Neutron Imaging Radiography (MJOLNIR) DPF*

A dense plasma focus (DPF) is a compact coaxial plasma gun which completes its discharge as a Z-pinch, producing short (<100 ns) pulses of ions, X-rays, and/or neutrons. In 2018, LLNL constructed and brought into operation the MJOLNIR (MegaJOuLe Neutron Imaging Radiography) DPF, which is designed for flash neutron radiography. This device has achieved neutron yields of up to 1.2e12 neutrons/pulse at 3.7 MA peak current and 1.2 MJ stored energy, with a measured neutron spot size as small as 3.8 mm FWHM. Higher stored energy (up to 2 MJ) commissioning is underway. The MJOLNIR team recently performed an assessment of the DPF's ability to meet neutron radiography requirements for dynamic experiments, including 1.0e13 yield, and 1 mm spot size FWHM. Further spot size improvements may be achieved through the use of noble gas dopants, a re-entrant cathode, and control of the anode's implosion radius. Further yield improvements may be obtained with anode shaping and an on-axis gas jet that creates a differential gas load. We present progress so far on these metrics, and potential paths forward for meeting these requirements.