Gas tungsten arc welding (GTAW), also known as tungsten inert gas (TIG) welding, is an arc welding process that uses a non-consumable tungsten electrode to produce the weld. The weld area and electrode are protected from oxidation or other atmospheric contamination by an inert shielding gas (argon or helium). A filler metal is normally used, though some welds, known as autogenous welds, or fusion welds do not require it. When helium is used, this is known as heliarc welding. A constant-current welding power supply produces electrical energy, which is conducted across the arc through a column of highly ionized gas and metal vapors known as a plasma. GTAW is most commonly used to weld thin sections of stainless steel and non-ferrous metals such as aluminum, magnesium, and copper alloys. The process grants the operator greater control over the weld than competing processes such as shielded metal arc welding and gas metal arc welding, allowing for stronger, higher quality welds. However, GTAW is comparatively more complex and difficult to master, and furthermore, it is significantly slower than most other welding techniques. A related process, plasma arc welding, uses a slightly different welding torch to create a more focused welding arc and as a result is often automated.
Cambridgeshire (abbreviated Cambs.)[note 1] is a county in the East of England, bordering Lincolnshire to the north, Norfolk to the north-east, Suffolk to the east, Essex and Hertfordshire to the south, and Bedfordshire and Northamptonshire to the west. The city of Cambridge is the county town. Modern Cambridgeshire was formed in 1974 through the amalgamation of two older counties: Cambridgeshire and Isle of Ely, comprising the historic county of Cambridgeshire (including the Isle of Ely); and Huntingdon and Peterborough, comprising the historic county of Huntingdonshire and the Soke of Peterborough, which historically had been part of Northamptonshire. Cambridgeshire contains most of the region known as Silicon Fen.
The county is now divided between Cambridgeshire County Council and Peterborough City Council, which since 1998 has formed a separate unitary authority. In the county there are five district councils, Cambridge City Council, East Cambridgeshire District Council, Fenland District Council, Huntingdonshire District Council and South Cambridgeshire District Council.