Design an‎d construction of a laboratory prototype plasma electron gun

11/19/2026 12:00:00 AM

Plasma electron guns are key components in advanced technologies such as thin-film deposition, surface modification, an‎d space propulsion, owing to their ability to generate stable, high-power beams. However, knowledge gaps in design an‎d optimization details have challenged the domestic development of this technology. The primary objective of this thesis is to design, construct, an‎d characterize a laboratory prototype of a miniature plasma electron gun based on a direct current (DC) plasma source operating in a high-vacuum regime. To achieve this goal, the research was conducted in three phases: simulation, fabrication, an‎d experimental testing. In the first phase, the distribution of electric an‎d magnetic fields in a structure with a divergent magnetic confinement configuration was simulated using COMSOL Multiphysics. The effects of parameters such as cathode voltage an‎d magnet positioning on electron trajectory tracing were analyzed. Simulation results indicated that this configuration is highly effective for electron confinement an‎d increasing their effective path length. Subsequently, three different electron gun designs were fabricated: a cold cathode an‎d two versions of a filamentary cathode with distinct mechanical structures. In the experimental phase, the cold cathode design failed to generate plasma. However, the designs based on a tungsten filament (inspired by the Kaufman ion source) successfully formed plasma an‎d were capable of extracting both ion an‎d electron beams. The final design, featuring a modified ceramic cathode base, demonstrated superior thermal an‎d mechanical stability. Experimental results showed that the plasma discharge current could be directly controlled by the filament current an‎d gas pressure. Although the extracted beams were visually confirmed, their currents were below the measurement resolution of the power supplies (<‎10 mA). This research successfully established the technical know-how for designing an‎d building a plasma electron gun, paving the way for future optimizations.

تفنگ الكترون پلاسمايي , چشمه پلاسماي جريان مستقيم , تخليه الكتريكي , خلأ بالا , محصورسازي مغناطيسي , چشمه يون كافمن

Plasma Electron Gun , DC Plasma Source , Electric Discharge , High Vacuum , Magnetic Confinement , Kaufman Ion Source

Ali Khosravi

Dr. Mostafa Salahshoor