Development and application of Langmuir probe system in pulsed glow discharge plasma in GADX

The Glow and Arc Discharge Experiment (GADX) system provides an ideal platform for investigating pulsed glow discharge during the initial plasma formation stage and arc discharge plasma during the jet formation stage in plasma-jet-driven magneto-inertial fusion (PJMIF). In the pre-ionization process of coaxial plasma guns for magneto-inertial fusion, the introduction of glow discharge technology significantly improves energy utilization efficiency. To diagnose the electron temperature (Te) and electron density (ne) in different regions during the pulsed glow discharge of the GADX system, a multi-channel Langmuir triple-probe diagnostic system was designed and applied in this study. The Langmuir probes are located at 50 mm in front of both the cathode and anode of the GADX system, with an azimuthal angle of 180° between each other, aiming to obtain plasma parameters in the negative glow region and the positive column region. Preliminary results of the pulsed glow discharge have been successfully obtained using the Langmuir probe diagnostic. This diagnostic capability is essential for studying the parameter evolution and dynamic processes of plasma during the pre-ionization stage inside coaxial plasma guns. In this study, the Langmuir probe diagnose system was used for the first time to observe azimuthal asymmetry in the pulsed glow discharge plasma of the GADX system, and the spatiotemporal evolution of plasma parameters in the negative glow and positive column regions was successfully measured, providing key experimental evidence for understanding the pre-ionization physics of PJMIF plasma guns.