Hydrogen ionic plasma formation using an Al plasma electrode with an enlarged single extraction hole diameter

A hydrogen ionic plasma consisting of positive and negative ions with a low fraction of residual electrons was generated using an aluminum plasma electrode (Al-PE) and a control electrode (CE) with a single extraction hole of 4 cm in diameter. By irradiating Al-PE with hydrogen plasma and varying the voltage applied to CE, either positive or negative ions were selectively extracted from Al-PE. When positive ions were extracted, electrons were generated in the downstream region of CE, whereas in the case of negative ion extraction, electron generation was negligible. Regardless of the extraction polarity, H−, H+, and H2+ ions were detected in the downstream region, along with multiple positive and negative molecular ion species. It is inferred that the dissociation of positive molecular ions generates electrons locally.