Analysis of a melting wire temperature probe applied to a plasma torch

A simple method to make a temperature measuremenitn an atmosphericp ressurep lasmat orch with a density of 10¹³ electrons/cm³is developed.T he method is based on thermal equilibrium and a detail analysis of heat loss from a copper wire placed in a torch. The wire diameter, which regulates heat loss, is systematically reduced to increase the temperature of the wire segment in the torch. At a critical wire diameter, the wire is about to melt suggesting that its temperature in the torch is reaching to the wire melting temperature. This temperature and an analysis of heat input from the torch and heat loss from the wire combine to provide a useful although approximate temperaturem easurementin the 1300- 2200 K range. Using this technique, the temperature of a plasma torch was determined to be approximately 1760 K.