Multi-second neutral beam injector (60kV, 6A) for plasma diagnostics in the upgraded T-15 device

A diagnostic neutral beam injector DINA-KI60 has been developed and produced for upgraded T-15 tokamak (Kurchatov Institute, Moscow). The system will be primarily used for measurement of the ion temperature by charge-exchange recombination spectroscopy (CXRS), for magnetic field measurements via motional Stark effect (MSE) and investigation of plasma turbulence by Beam emission spectroscopy (BES). The ion source provides 60 keV, 6 A hydrogen beam with low angular divergence less than 10 mrad. Ions are extracted from a plasma created by an arc-discharge source with cold cathode and, after accelerating and focusing, are neutralized in a gas target. The extracted beam has about 86% of full energy specie. The grids of ion optical system are spherically curved providing geometric focusing of the beam at a distance 4 m. Diagnostic neutral beam has been successfully tested at Budker Institute of Nuclear Physics at 2 seconds pulse duration with modulation of the beam (duty ratio from 1:1 to 1:3).