Characteristics of a 30 kW plasma torch

Abstract

A 30-kW torch for heating air has been built using scaling law techniques. The current-voltage characteristics were determined over a wide range of parameters: 60 to 120 A, 200 to 460 V, and gas flows of 2.8 to 13.7 g/s. The thermal efficiency varied from 62% to 76%. The results yield the expected V infinity I/sup -0.3/ law. The result with the highest mass flow suggests that higher injection velocities may play a role. Experience showed that the erosion of the cathode plays an important role in the operation of the torch. Eroded cathodes systematically yielded lower voltages, lower power levels, and lower efficiencies.<>