Factors Affecting the Operating Characteristic of the Zetatron: A Small Neutron Generator for Borehole Logging

The Zetatron is a small deuterium-tritium accelerator which uses a reflex discharge ion source and approximately 130 kV acceleration from a pulse transformer. The dominantly D(T,n) He reaction takes place in an occluder target consisting of a Scandium deuterotritide film deposited on a molybdenum slug. The instantaneous energy deposition rates at the target, the species present in the beam, and the beam profile determine target life and neutron output characteristics. The target temperatures are calculated for a single pulse and compared to measurements of the thermal profile on a specifically-prepared, thin-target substrate. Target images are shown which illustrate the beam imaging process. The beam is found to consist of an intense spot 2-4 nim in diameter surrounded by a halo approximately the size of the target. The implications of such a beam profile are discussed. Computer codes are used to model the beam and to describe the parts of the tube that control the beam characteristics.