Diagnostics of Plasma Jet Generated in Water/Argon DC Arc Torch

Thermal plasma jet generated by the torch with water/argon stabilized arc was investigated. Plasma torches of this type have been used for plasma spraying, waste treatment and gasification of organic materials. Electric probes, enthalpy probe, and schlieren photography were used for diagnostics of the jet in the region downstream of the torch exit. Information about structure and shape of plasma jet was evaluated from the measured data. Large extent of radial plasma spread and high level of turbulence were found from both the schlieren and the probe diagnostics. Plasma temperature corresponding to measured ion saturation currents was determined using calculated composition of plasma assuming ex-istence of local thermodynamic equilibrium.

Diagnostics of Hybrid Water/Argon Thermal Plasma Jet with Water, Ethanol and Their Mixture Injection to Plasma

A plasma torch with the water/argon stabilization of an arc is characterized by extremely hot and high velocity plasma together with the relatively low flow rate of plasma, therefore, the torch might be properly used for plasma suspension spraying. Enthalpy probe and emission spectroscopy measurements were carried out at constant arc power with the combination of the injection of water, ethanol or their mixture to the plasma jet to diagnose the changes in temperature, heat flux and other characteristics.

Characterization of the Expanded Plasma Jet Generated at Reduced Chamber Pressure

Very low pressure plasma spraying has been attracted attention due to special properties of the expanded plasma jet which may probably deposit specific and unique structure coatings, such as columnar structure coatings. The forming of the coatings is affected by plasma generating and working conditions. These operating parameters such as arc power, plasma gas flow rate, and chamber pressure have influences on pressure, enthalpy and temperature of plasma jet. In this work, an enthalpy probe is applied to measure the enthalpy of argon-hydrogen plasma jet generated at chamber pressure of 3000 Pa and 50Pa. The results showed that the temperature of plasma jet reached to 11000 K at 25 mm from nozzle exit, and then dropped slowly to 7000 K at 400 mm.