Cylindrical IEC Fusion Neutron Source for Broad Area NAA

Abstract

The development of a unique long cylindrical neutron source for broad area neutron activation analysis (NAA) is presented. This source uses inertial electrostatic confinement (IEC) to produce 2.54 MeV D-D or 14.1 MeV D-T fusion neutrons for applications ranging from security inspection stations to driven-subcritical research assemblies. This design uses a biased grid to initial in a unique “star” mode plasma discharge forming beam-background gas (target) fusion. In spherical geometry it routinely produces ∼108 2.54-MeV D-D fusion neutrons/s at steady-state. Pulsed operation has achieved up to 109 neutrons/sec. (equivalent to 1011 n/s using D-T fill). Indeed, a version of the spherical IEC has been produced commercially as a portable neutron source for industrial NAA applications. Recently a cylindrical (2-dimensional version) design based on the spherical unit has been developed. This provides a unique long “line-like” neutron source for use in broad area NAA. This IEC forms ion beams in the volume between the grounded wall and the concentric cylindrical grid. Those beams converge in the center, much like in the star mode spherical IEC. To date, neutron yields of up to 108 D-D neutrons/sec have been achieved with the cylindrical device. A sealed-off unit using getters for gas storage-control has been developed to simplify use in practical applications such as a luggage inspection station. Such units would be filled with deuterium at a central fueling facility, and sent out to the field. After extended operation, they would be returned to this facility for refilling.