Development of Convergent D-D Fusion Neutron Generator with Large Pulse Current

A neutron production rate (NPR) of 2.3 × 10⁶ 1/sec has been achieved in a spherically convergent D-D fusion neutron generator with the applied voltage 60 kV and the steady-state discharge current 40 mA. The scaling of NPR with respect to the current, however, is linear. The results revealed the fact that the fusion reaction occurs mainly between the accelerated molecular ion D₂⁺ and neutral gas D₂⁰. In considering a future application of the neutron source, the dependence on a square current, i.e., the fact that the main reactions are caused by accelerated ion beam-beam colliding fusions is most desirable. A new IEC device has been constructed in order to obtain evidence of beam-beam colliding fusions. The device is designed to operate in a short pulse of the voltage -70 kV and the large current 100 A. This is the first experiment to draw a current of several tens of amperes in IEC devices. The discharge characteristics were studied with regard to the relations of the current, applied voltage and gas pressure. The neutron production rate was also measured, and the conditions to realize accelerated ion beam-beam fusion are discussed.