Concentration of a Plasma Energy Flow by a Blowing Gas

Control of energy flow density is required when a plasma flow is used for material treatment. For this purpose, hydrodynamic, magnetic or mechanical control may be used. The object of this study is to suppress the outward radial flow of the plasma flow. Sharpness of heat flux distribution to a flat plate is required in plasma cutting. Therefore, the following two experiments were carried out. One was to sharpen the enthalpy flow distribution of a thermal argon plasma jet, and the other was to sharpen the heat flux distribution to the plate. These energy flow densities of the plasma flow were raised by an inward radial blowing gas. This radial blowing gas was injected through a circumferential slit around the jet nozzle exit. Q-value, defined as the ratio of maximum energy flow to the half-value width, is adopted as an evaluation of sharpness. Not only the Q-value of enthalpy flow of the plasma but also that of heat transfer to the plate reached maximum with the radial blowing gas flow rate.