A NEW METHOD FOR LOW VELOCITY PLASMA TEMPERATURE PROFILE MEASUREMENT

This paper is focused on thermal plasma temperature measurements comparing standard enthalpy probes with a new developed quartz probe. Enthalpy probes doesn't give accurate temperature measurements for low velocity plasmas. We therefore developed a new method using a simple water cooled quartz tube and an inverse thermal computation. This method amends the range of conditions for which intrusive techniques may be applied as plasmas diagnostics.
Hilpert's law is used to compute the convection exchange coefficient between a laminar plasma flow and a perpendicular cylindrical water cooled quartz tube. The knowledge of the thermal power exchange permits the plasma temperature to be calculated.
The results are compared with enthalpy probe measurements and are validated by global calorimetric measurements performed on our 35 kW high frequency plasma installation. The plasma gas used is argon. This method can be extended to different gases, to high velocity plasmas, or to arc plasmas temperature diagnostics.