Expansion characteristics of a plasma jet in the stepped-wall liquid chamber

The stepped-wall liquid chamber is an effective way to control the interaction instability during the expansion process of a plasma jet in the working fluid. The experiment was carried on to observe the plasma-liquid interaction in the stepped-wall liquid chamber. Based on the experiment, a two-dimension unsteady calculated model of a plasma jet expanding in liquid was established to investigate the jet expansion and flow field characteristics. The plasma jet gradually fills the steps of the liquid chamber, and its axial expansion is faster than the radial expansion. The vortex formed internal the plasma jet splits into two small vortices as time goes on. The low-pressure vortex is formed at the corner of the step, which increases the radial expansion of the plasma jet. Increasing the wall structure factor (n), the turbulent mixing is increased, the axial expansion ability of the plasma jet is decreased, and the pressure of the head high-pressure area and the thermal diffusion range of the plasma jet are decreased. The formula for estimating the axial displacement of a plasma jet is obtained for n is 0.4∼0.8.