Cryogenic Deuterium Pellet Injection for Enhanced Neutron Output of a Dense Plasma Focus

In his fiscal year (FY) 2024 Site-Directed Research and Development (SDRD) project “Cryogenic Deuterium Pellet Injection for Enhanced Neutron Output of a Dense Plasma Focus”, principal investigator Daniel Lowe is developing methods to increase the neutron yield of a Dense Plasma Focus (DPF) using cryogenic deuterium techniques. By increasing the neutron output of the DPF, this project aims to enable increased accuracy in support of the Neutron Diagnosed Subcritical Experiments program and hopes to offer an alternative neutron irradiation environment to support survivability programs.

This SDRD project is especially unique due to its use of deuterium, an isotope of hydrogen, in a solid form. Daniel and his team freeze deuterium gas into solid ice at a temperature between 4 and 13 Kelvin (or -452 degrees Fahrenheit), which is approximately the temperature of outer space. Hydrogen isotopes that have been frozen into a solid form are very rare because they do not naturally occur on earth in the solid phase.

To cryogenically freeze deuterium gas, Daniel and his team have recently begun using liquid helium. Liquid helium is significantly colder than liquid nitrogen, which has often been used at the Site for radiation detection and specialized vacuum systems. Specialists from Oak Ridge National Laboratory (ORNL) helped train five NNSS employees involved with this project on the correct methods to handle and transport liquid helium, and these employees have been successfully implementing ORNL’s strategies. This is the first training of its kind to have been done at the NNSS, and it enables future R&D efforts that may require cryogenically frozen deuterium targets.