MICROWAVE-EXCITED PLASMA TORCH - 2 COMPLEMENTARY CONFIGURATIONS

This paper describes the ''flame'' obtained at atmospheric pressure by a microwave discharge (2.45 GHz) produced using two different plasma torch configurations sharing the same impedance matching device. These two torches differ externally by the shape of their microwave field applicator relatively to the way the carrier gas is injected: a conical nozzle with axial gas injection (the ''TIA'' system) in one case, and a rod with coaxial gas injection (the ''rod-torch'' system) in the other. The TIA produces a well defined tongue with a high luminosity and a maximum of charged particle density at the nozzle's exit, while the rod-torch leads to a lower density plasma but to a higher gas temperature in the vicinity of the applicator. The plasma of the rod-torch is closer to local thermodynamic equilibrium (LTE) than that of the TIA.