Design and R&D for manufacturing the Beamline Components for MITICA and ITER HNB

The design of the beamline components of MITICA, the full prototype of the ITER neutral beam injectors, is almost finalised and technical specifications for the procurement are under preparation. These components are the gas Neutraliser, the electrostatic Residual Ion Dump, and the Calorimeter. Electron Dump panels are foreseen sideways at the bea m entrance section of the Neutraliser to protect the cryo - panels from electrons stripped in the 1MeV accelerator. High heat fluxes, up to 15MW/m2, with enhanced heat transfer in subcooled boiling conditions will occur in the actively cooled CuCr1Zr panel e lements provided with twisted tapes as turbulence promoters. These severe heating conditions will be applied steadily, as the maximum pulse duration is one hour, and cyclically so requiring to fulfil fatigue, creep, and ageing verifications. The design of the beamline components implements and improves technical solutions already tested: the neutralisation gas will expand through injection nozzles located at three alternative positions along the gas cell to look for an optimised neutralisation efficiency, t he electric field deflecting the residual ions will be realised by applying the biasing voltage of - 20kV added to a trapezoidal waveform of +/ - 5kV at the frequency of 50Hz in order to spread the power and to increase the fatigue life of the panels, the ex - vessel pneumatic actuator with the double barrier vacuum feedthrough will close the Calorimeter panels for conditioning and commissioning in ITER and for testing of the actuation mechanism in MITICA. Special R&D activities have been undertaken to support t he design: manufacturing of thick twisted tapes leading to an increased cooling performance while maintaining flow rate requirements, bending of CuCr1Zr swirl tubes, verification for permanent deformations due to stress relaxation after heating of CuCr1Zr swirl tubes, double side deep drilling of 2m long CuCr1Zr plates. Alignment requirements and remote handling compatibility have been verified.