Negative hydrogen ion production during extraction and acceleration from an aluminum plasma grid

This study investigates the mechanisms underlying the production, separation, and detection of negative ions and electrons using an aluminum plasma grid (Al-PG) by varying the control grid voltage, extraction grid voltage, and analyzer limiter plate voltage. The control grid is employed to regulate the extraction of different ions from Al-PG. Negative ion currents are measured with a hollow collector, and electron currents are measured with nozzle electrodes, which serve to separate the electrons. By varying the electrode potential and applying a magnetic field, the influence of the spatial electric field distribution on the transport and separation of electrons and negative ions is analyzed. The results show that the negative ion current observed during positive ion extraction from Al-PG exceeds that obtained during negative ion extraction from Al-PG. Furthermore, a pronounced increase in negative ion current was observed in the regions between the control grid and the extraction grid or between the extraction grid and the analyzer limiter plate. By isolating the contributions of negative ion extraction and current enhancement in different regions, this study demonstrates that the electric field between the extraction grid and the analyzer limiter plate plays a significant role in the observed increase in negative ion current. Additionally, the findings indicate that the electron current increases with the rise in analyzer limiter plate voltage and eventually approaches a nearly constant value. These findings offer valuable insight into optimizing negative ion sources for various applications.