Tritium operation of the JET neutral beam systems

Neutral Beam Injection (NBI) is a very flexible auxiliary heating method fo r tokamak plasmas, capable of being efficiently coupled to the various plas ma configurations required in the Deuterium-Tritium Experimental campaign ( DTE1) undertaken in the JET device during 1997. In particular, experiments for high fusion yield and amplification factor Q require intense NBI heatin g, and for maximum performance and optimum fuel mixture control in Deuteriu m-Tritium (D-T) plasmas it was necessary to operate the JET NBI systems in both deuterium and tritium. All technical aspects of the modifications to t he JET NBI systems for compatibility with tritium operation are discussed, and the associated commissioning is described, including preparatory commis sioning using deuterium. Problems experienced and their resolution are high lighted. Some specific beamline physics issues relating to tritium operatio n an discussed in detail, in particular experimental measurements of beam-t arget D-T reactions occurring in beam-stopping elements and associated mode lling of isotope exchange in these components. Data on NBI performance and tritium usage and recovery for the DTE1 campaign are presented. (C) 1999 JE T Joint Undertaking. Published by Elsevier Science S.A. All rights reserved .