Preliminary efforts toward a compact D–D neutron generator based on a helicon plasma source

This study attempted to apply a helicon plasma source to a compact Deuterium–Deuterium (D–D) neutron generator, ultimately achieving a maximum neutron yield of up to 1.27 × 109 n/s with stable operation for over 1 h. By investigating deuterium plasma characteristics with a Nagoya-III antenna in a permanent magnet helicon device, we established a correlation between its atomic spectral lines and plasma density. The results show that the transition power for deuterium plasma from the inductively coupled mode (H mode) to the magnetically enhanced inductively coupled mode (ME-H mode) is ∼400 W. However, constrained by the maximum power limit of the matching network (1000 W), we were unable to achieve wave coupled mode (W-mode) operation. Then, based on the discharge characteristics of the helicon deuterium plasma, a compact D–D neutron generator utilizing helicon deuterium plasma was constructed, and experiments on deuterium ion beam extraction were carried out. It was observed that when the discharge mode transitions from H-mode to ME-H-mode, the extracted beam intensity increases several-fold. Furthermore, there exists an optimum gas feed rate that maximizes the extracted beam intensity, and compared to inductively coupled ion sources, the system demonstrates higher gas-utilization efficiency. Although the power limitation of the matching network prevented the helicon discharge from reaching W-mode, the results of this study confirm the distinct advantages of helicon plasma sources for application in compact D–D neutron generators, thereby laying the groundwork for the further adoption of helicon ion sources in this field.