In GTAW, what does the tungsten electrode primarily do?

In Gas Tungsten Arc Welding (GTAW), the primary role of the tungsten electrode is to maintain an arc for welding. The tungsten electrode is non-consumable, meaning it does not melt during the welding process. Instead, it gets extremely hot to create an electric arc between itself and the workpiece, which generates the heat required for welding.

When the arc is established, it ionizes the air around it, providing a stable source of heat that can melt the base metal and, if used, the filler material. The ability of the tungsten electrode to maintain a consistent arc is crucial for achieving a high-quality weld, as it directly affects the temperature and stability of the molten pool.

The other options describe functions that are not the primary role of the tungsten electrode in GTAW. While the process does involve filler materials, thermal resistance, and gas flow controls, these are either supplementary to the welding process or pertain to other components rather than the main function of the tungsten electrode itself.