Other than in tungsten inert gas welding (TIG), gas is additionally ionized to neck down the arc in micro-plasma-welding. This focuses the released energy easily 10 times as sharply as in TIG welding. Argon, a plasma gas, is mostly used, or argon/hydrogen and argon/helium gas mixtures.
The process is used with metal sheet or buildup thicknesses up to about 1 mm thick and currents up to about 20 amperes. Plasma welding is mostly mechanized, since its manipulation is comparatively difficult on account of the narrow arc.
Advantages of microplasma welding over TIG welding: The high energy concentration produces narrow, deep weld pools permitting high welding rates to be achieved. The heat-affected zones are also appreciably smaller, reducing the risk of heat distortion of the parts.