Commissioning and first operation of the W VII-AS neutral beam system

The neutral injection (NI) system of the Wendelstein VII-AS modular stellarator has been commissioned and was successfully operated during the first experimental phase of W VII-AS. The NI system consists of two boxes of the LPNI/ASDEX type positioned in the co and counter directions to reduce beam-driven currents and momentum input. More than 870 injection shots and over 12000 internal shots for source conditioning and beam diagnostics were performed, showing the advantages of the programmable controller used and the routinely performed beam diagnostics with a MicroVax II computer. The main components specific to NI/W VIII-AS and initial operational experience are described. The water-calorimetric measurements of the conically tapered duct are discussed. The measurements were taken after the duct was subjected to direct beam losses and they show the conditioning of the duct wall