Beam transport and interactions with beam-line components in MITICA injector

The injection of high energy beams of neutral particles is a fundamental method for plasma heating to ignition in the advanced fusion devices. In order to realize the neutral beam injectors (NBIs) operating on the ITER tokamak the construction of a dedicated test facility is in progress at Consorzio RFX, Padova. This facility will host a full scale prototype of the heating neutral beam to be installed on ITER, named MITICA (Megavolt ITER Injector and Concept Advancement). Its requirements about extracted current (70 A of H- or 56 A of D-), beam energy (1 MeV), and pulse duration (1 hour) represent a large extrapolation from existing devices, thus motivating the extensive work on numerical modeling required to optimize the final design and the injector performances. Among the critical issues to be solved, an important topic is the simulation of power deposition along the beam line, originating from several sources: primary beam, co-accelerated electrons, and secondary production by beam-gas, beam-surface, and electron-surface interaction. These issues are coped with a comprehensive 3D model of the beam transport and a power deposition simulation along the injector. The code uses as input the results of the most updated analyses of the ion source, and calculates the particle motion in electro-magnetic fields, including the secondary production, the re-ionization of the beam, and the interactions with the surfaces. The calculations here reported are mainly focused on the phenomena occurring in the Residual Ion Dump (RID)