Operation and Life of the Zetatron: A Small Neutron Generator for Borehole Logging

The zetatron is a small sealed-off D-T accelerator being used for pulsed neutron production in Uranium borehole logging experiments. The tube utilizes a zirconium gas reservoir, Penning type ion source, and up to 130 kV ion extraction with ion beam focussing and secondary electron supression. The mixed D-T beam is incident on a scandium film target and produces in the pulse mode up to 8 × 106 neutrons/sec peak rate at a source current of 2.5 A and target voltage of 130 kV. In the borehole logging application the tube, operating at 100 pps, dissipates an average power of about 10 watts. Life testing has demonstrated an average tube functional life of 148 hours and a shelf life in excess of one year. Life limitations include a steady degradation in neutron output of about 50% in 100 hours and eventual tube puncture fractures that are catastrophic.