Characterization of the Expanded Plasma Jet Generated At Reduced Chamber Pressure

Low pressure plasma spraying (LPPS) is nowadays a well-established thermal spray process with a broad variety of important applications for functional surface coatings. It uses a low pressure environment (chamber pressure between 50 Pa and 10000 Pa) and yields supersonic plasma jets. In this study, an enthalpy probe is applied to measure the enthalpy of argon-hydrogen plasma jet generated at reduced chamber pressure. Attempts are also made to measure the pressure of plasma jet by u-tube fixed on the enthalpy probe. The temperature and velocity of plasma jet were calculated by measuring the enthalpy and pressure at different axial distances of the plasma jet. 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.