ARC Welding Equipments

The electric arc is formed between an electrode (which is always made of tungsten) and the work-piece.
The key difference from GTAW is that in PAW by positioning the electrode within the body of the torch the plasma arc can be separated from the shielding gas envelope.
Actually all welding arcs are (partially ionized) plasmas but, the one in plasma arc welding is constricted arc plasma.
The constriction increases the temperature of the arc and also gives it the shape of a fine beam.
This enables welding at high speed, greater penetration, narrow HAZ (heat affected zone) and minimum heat input to the job.