Diagnostic Neutral Beam for ITER—Concept to Engineering

Following the allocation of the procurement of the diagnostic neutral beam (DNB) to the Indian DA, a series of tasks have been undertaken to first assess the DNB configuration and arrive at an optimal beam-line configuration folding in the gas-feed and vacuum-pumping requirements. Specific emphasis is placed on the thermal, structural, and electrical designs of beam-line components, in order to ensure their compatibility with the criteria specified for ITER in vessel components, i.e., Structural Design Criteria for In-Vessel Components. The detailed assessment of manufacturing technologies and their compatibility with the ITER standards forms an integral part of the design. A common approach to manufacturing for DNB and heating-and-current-drive NB components shall be undertaken through a comprehensive prototyping phase which shall lead to built-to-print specifications. In addition to safety and remote-handling issues, the design also addresses the requirements of interfaces related to other systems such as cryo, hydraulic, pneumatic, vacuum pumping, gas feed, civil, power supplies and transmission, CODAC, etc. The successful delivery of DNB is dependent on two critical R&D aspects: 1) the production of a uniform low-divergence beam from the beam source and 2) a well-controlled transmission through lengths of $\sim$22 m. The first shall primarily be a subject of the Ion Source Test Facility—SPIDER [part of NB test facility (MITICA in Padova)]—where India is involved as a collaborator and the Indian test bed, where issues for DNB beam source which were not resolved in the SPIDER would be taken up. The second shall form one of the primary objectives of the Indian test bed to characterize the DNB. This paper presents the progress in DNB from the concept level to an engineered system along with the plans for system integration and an R&D intensive implementation.