Electron conduction and ionization-acceleration decoupling in a 3 kW-Class double-stage anode layer Hall thruster: Voltage effects analysis

Double-stage anode layer Hall thrusters theoretically enable ionization-acceleration decoupling, yet lack systematic control mechanisms and quantitative criteria. This study investigates double-anode voltage effects on decoupling efficiency and electron transport via particle-in-cell (PIC) simulations, Faraday probes, and spectroscopic diagnostics. Results show ionization voltages of 0–30 V reduce the second-stage anode current by 85 %, attributed to enhanced low-energy electron collection by the first-stage anode near walls. A total ionization rate R_ion,V is defined to quantify decoupling, representing ionization events per unit time in regions where potential exceeds threshold V. Ionization voltage primarily governs pre-ionization completeness, while acceleration voltage determines acceleration zone positioning. Under the U_a=400V\U_d=60V configuration, R_ion,350 increases by 62 % compared to U_a=400V\U_d=0V, with a corresponding 8.4 % specific impulse gain. This configuration achieves a 126 % improvement in R_ion,350 over U_a=350V\U_d=60V, yielding a 9.8 % specific impulse improvement. Numerical simulations predict an optimal ionization voltage range (60–90 V): lower voltages cause insufficient pre-ionization, while higher voltages degrade current utilization and specific impulse. At U_a=400V, specific impulse peaks at U_d=90V, whereas current utilization maximizes at U_d=60V. However, the total ionization rate R_ion,400 exhibits sustained growth as the ionization voltage increases from 0 to 150 V.