Generation and propagation characteristics of vacuum discharge plasma with co-axial electrodes

Vacuum discharge plasma is generated using a single-pulse power supply with 13 s pulse width and 100~300 A discharging current. Two types of co-axial electrodes, namely the tubular electrode and the trumpet electrode, are employed as anodes. The electric field distribution with two electrodes is simulated by MAXWELL 3D simulation software. The parameters of vacuum discharge plasmas, such as electron density, electron temperature, space potential and ion kinetic energy, are measured by the Langmuir probe method to investigate the impact of co-axial electrode configurations on the plasma generation characteristics. Moreover, the effects of cathode materials on the ion velocity and kinetic energy are discussed, as lead, aluminum, and copper are used as the cathode material, respectively, with the trumpet electrode configuration. Experimental and simulation results show that the plasma generated with the trumpet electrode exhibits higher discharge current, greater plasma density, and lower breakdown voltage compared to the tubular one. The aluminum cathode can generate plasma with the highest diffusion velocity, while the lead cathode yields the maximum ion kinetic energy of plasma.