Plasma Arc Welding (PAW) is a process where an electric arc is formed between an electrode and the workpiece.  With PAW a narrow deep penetration of the weld is possible. 

• Is an extension of the gas tungsten arc welding (GTAW) process.
• The arc is formed between an electrode (which is usually but not always made of a sintered tungsten) and the workpiece.
• 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.
• The plasma is then forced through a fine-bore copper nozzle which constricts the arc and the plasma exits the orifice at high velocities (approaching the speed of sound) and a temperature approaching 20,000 °C.
• Plasma arc welding is an advancement over the GTAW process.
• This process uses a non-consumable tungsten electrode and an arc constricted through a fine-bore copper nozzle. PAW can be used to join all metals that are weldable with GTAW (i.e., most commercial metals and alloys).
• Several basic PAW process variations are possible by varying the current, plasma gas flow rate, and the orifice diameter.

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