Enthalpy probe diagnostics of an atmospheric pressure argon microwave induced plasma

An argon microwave-induced plasma (MIP) at atmospheric pressure was generat ed in a TE10 mode waveguide. The discharge was sustained by a relatively lo w absorbed power of around 215 W. An enthalpy probe was used to characteriz e the argon MIP discharge, yielding values of enthalpy, velocity and heavy particle temperature along the jet axis. The theory of the enthalpy probe o peration and calibration is reviewed and the system for its implementation is described. The heavy particle temperature is found to be about 1600 K an d the velocity to be about 150 m s(-1) at the exit plane of the discharge t ube for an argon how rate of 1.61 min(-1). Although the assumption of local thermodynamic equilibrium is required to determine the temperature and vel ocity in the jet from the enthalpy probe measurements, it is argued that th e values obtained should be reasonable even if, as expected in MIPs, the el ectron temperature is significantly higher than the heavy particle temperat ure.