ANALYSIS OF PLASMA JETS GENERATED IN GAS AND GAS-WATER TORCHES

摘要

The behaviour of plasma jets generated by gas and gas-water torches is different. The difference arises from plasma torch arrangements and from a way of arc stabilisation. In the gas torch an arc is ignited between a tip of a cathode and an anode operating as a nozzle and plasma gas is supplied around the cathode. The hybrid gas-water torch combines two types of stabilization: by water vortex and by gas flow. The arc is generated from the cathode and passes through the channel inside the water vortex towards the external rotating anode resulting in a long arc with high voltage. The generated plasma exhibits high values of enthalpy and temperature and low values of density. Thus, the density ratio between plasma and surrounding is much lower than in the gas torch, causing stronger entrainment of the cold ambient air. Moreover, the main plasma flow interacts intensively with an anodic jet, which is formed at the position of the anode attachment. As a result, additional perturbations and deflection of the main plasma flow from the torch chamber axis occur. The mentioned factors affect transfer mechanisms in the gas-water jets. The work considers behaviour of the jets generated by both torches.