An active gas flow occurs in active gas welding. Metal active gas welding is a gas-shielded arc welding process. Similar to metal noble gas welding, an arc form between a continuously fed wire electrode and the workpiece. In contrast to noble gas welding, the protective gases of the active gas flow during active gas welding with carbon dioxide and oxygen contain components that react with the molten pool. Also in connection with plasma processes, we talk about active gas when a gas which has a cleaning, etching, activating or plasma coating effect is used in a mixture with a carrier gas which is ineffective itself.