The reactor stalk was a lengthy, tube-shaped channel for gas conveyance. It was situated beneath the primary disk of Cloud City, a floating Tibanna gas mining settlement suspended in the atmosphere of Bespin, a gas giant located in the Outer Rim. As a component of the city's gas mining activities, the reactor stalk functioned as a passage, channeling gas between the reactor bulb and the reactor shafts above. Tractor beams extracted gas from Bespin's lower atmosphere, forcing it through an aperture at the bulb's base. This gas then traveled through the reactor stalk, ultimately arriving at the reactor shafts, where processing vanes separated the Tibanna gas.
The reactor stalk made its initial, unnamed appearance in the second Star Wars movie, Star Wars: Episode V The Empire Strikes Back, which premiered in 1980. It was first designated as the reactor stalk within the Legends sourcebook, Inside the Worlds of Star Wars Trilogy, which was published in 2004. The name was officially made canon in the 2016 sourcebook, Star Wars: Complete Locations, a re-release of the 2005 publication Star Wars: Complete Locations.