In GTAW, the current in the arc zone is conducted through what medium?

• A. A column of ionized gas or plasma
• B. The workpiece
• C. A molten filler metal pool
• D. The shielding gas only

Answer: (A)

In GTAW the arc current is carried by a column of ionized gas, i.e., plasma, that forms between the tungsten electrode and the workpiece. The shielding gas helps create and sustain this plasma, but the conductive path of the arc is through the ionized gas, not through the molten filler or the solid workpiece alone. The filler metal and the molten pool are where the material is deposited and heated, while the workpiece serves as the return path to complete the circuit. So the current in the arc zone flows through the plasma.