Instrumentation and diagnostics for the ITER Neutral Beam System

The ITER Neutral Beam (NB) System consists of a 100 keV diagnostic injector (DNB) and two 1 MeV heating and current drive injectors (HNB). Injection will be done in the different phases of the experimental programme, ranging from low activation operation with hydrogen and helium plasmas, deuterium plasmas, and finally full performance operation with deuterium–tritium mixtures. The injectors will be operated in a harsh environment with high levels of neutron and gamma radiation from the torus. A high stray magnetic field from the tokamak is reduced to acceptable levels for the region up-stream of the residual ion dump (RID) by a combination of a passive magnetic shield and active correction and compensation coils (ACCC). This broad range of requirements imposes a high flexibility, a high availability and reliability of the instrumentation and on the diagnostics that will be used.