Diagnostics of the ITER neutral beam injector and test facility

ITER design requires delivering to the plasma a total power of 33 MW up to one hour in a stationary condition by two heating neutral beam injectors (HNB). This level of power is provided by negative ion beams generated by an RF source and accelerated at 1 MeV. The HNB specifications have never been simultaneously achieved so far and therefore a development programme has started to demonstrate the feasibility of a prototype injector and to optimize its performances. This programme comprises the ELISE RF source at IPP-Garching and a neutral beam test facility at Consorzio RFX in Padova, Italy, comprising SPIDER, a 100 kV negative hydrogen/deuterium RF source, fullsize prototype of the HNB source, and MITICA, a prototype of the full HNB. The mission of this programme is to guarantee reliable and efficient operation of HNB on ITER, where it will be impossible to have a direct view of the plasma in the source and of the beam in the injector, but a much reduced set of diagnostics will be available, mainly thermocouples. The diagnostics to be installed on SPIDER and MITICA are therefore essential to qualify and optimize the HNB for ITER in a full scale, full performance device, and to assess the amount of information on the source and beam which can be gathered by means ofthe HNB set of diagnostics. Sufficient instrumentation has then been included in each component to monitor its performance within the design envelope, toalert plant operatorsof the onset of operation outside design margins and to monitor source and beam characteristics to improve the injector performance. The test facility will also be the natural choice for hosting experiments on innovative concepts within the development of the DEMO HNBs, which will also operate at1 MV, but looking for more efficient neutralization techniques and cesium free source operation.