A VAPORISER FOR GENERATING FEED GAS FOR AN ARC CHAMBER

摘要

A vaporizer for generating a feed gas for an arc chamber is provided to immediately terminate the supply of the feed gas by forcibly cooling a heating element when the heating element is switched off. An elongate crucible(1) is arranged to contain a source of material, and a heater heats the source to generate a feed gas. A cooling duct(5) is arranged to extend along substantially the entire length of the crucible to receive cooling fluid and cool the source of material. The cooling duct is wound in a helical configuration around the crucible. The heater has a heating element helically wound around the crucible with the same helical pitch as the cooling duct but axially offset.