Numerical study of a plasma jet for plasma-assisted laser cutting

Laser fusion cutting commonly applies a high-pressurized nitrogen gas jet to blow the molten material out of the cut kerf. However, theoretical considerations suggest that the use of a plasma jet may offer some advantages over this conventional approach. In this preliminary investigation, the characteristics of a non-transferred plasma jet for the application as auxiliary gas in laser beam cutting are analyzed using numerical CFD simulation. Based on this study, a first prototype of a plasma jet generator was manufactured and used in initial cutting experiments on 6 mm thick AISI 304 stainless steel. Two different cooling concepts for the plasma torch were considered and investigated in practice. Suitable values for the nozzle exit diameter, the distance between the electrodes of the plasma torch, the auxiliary gas flow rate and the electric current were identified both model-based and experimentally. The achieved cutting performance is considered a proof-of-principle of the suggested approach of a plasma-assisted laser beam cutting process.