Intense Neutron Source Target Test Facility: A 200 kV, 200 mA dc, Deuterium Ion Accelerator

Abstract

A 200 kV, 200 mA dc, deuterium ion accelerator has been constructed to evaluate high-temperature hydride materials such as scandium and erbium for use as targets in D-T neutron generators. The metal hydride film is deposited on a water-cooled, copper substrate designed to handle power densities of 40 MW/M2 while maintaining a surface temperature of ≤ 450°C. The goal of this program is to develop a target for a D-T neutron generator capable of producing 101 neutrons/s for use in cancer therapy. The accelerator employs a small duopigatron ion source which is capable of delivering a 200 mA deuterium ion beam that is composed of 60% atomic ions. The ion source is held at positive high voltage and a beam is formed with a single stage accel gap. An extractor electrode is biased negative about 2 kV to suppress secondary electrons and to define the point along the beam axis where the beam is space-charge neutralized by the trapped secondary electrons. The distance from the plasma expansion cup to the target is 0.6 m. Ion beam diameters at the target have been determined from measured infrared radiance profiles of the target due to beam heating. Data are presented on ion beam diameters for several operating conditions and accelerator geometries. D-D neutron output rates of 6 x 1010 neutrons/s have been measured with a 200 kV, 180 mA beam on erbium and a 180 kV, 160 mA beam on scandium.