Improvement of plasma jet in atmospheric pressure plasma polishing

Atmospheric pressure plasma polishing is an efficient method to achieve ultra-smooth surfaces. The employed plasma torch is a widely adopted tool to generate stable plasma jet. The purpose of investigating and improving the performance of plasma jet in high pressure, fluid finite element analysis is to study the influences of gas flow and torch structure features on the distribution of reactive radicals outside the discharge zone. Afterwards, atomic emission spectroscopy is utilised in plasma jet experiments to test the simulation results. Surface roughness and removal profile after machining are also detected to demonstrate the validity of structure modification. It is indicated that species and concentration of reactive radicals in plasma are not changed remarkably by convergence structure. Instead, the convergence structure is helpful to eject regular plasma flame so as to achieve predictable removal profile. Meanwhile, the optimal parameters are determined for new torch, with which higher removal rate and more favourable profile are obtained.