Final design of the High Voltage Deck 1 and Bushing for MITICA: The ITER Heating Neutral Beam Injector prototype

•HVD1 and HVBA are unique devices for size, electrostatic and mechanical features.•Main design choices to satisfy the challenging technical requirements are presented.•The supporting electrostatic, seismic and thermal analyses are reported.•Next procurement steps and tests to verify the key design choices are also reported. The Ion Source of the ITER Heating Neutral Beam Injector (HNB) is polarized at −1MVdc to ground. A large-1MVdc air-insulated Faraday cage (12.5m (L)×8.4m (W)×9.6m (H)), called High Voltage Deck 1 (HVD1), hosts the Ion Source and Extractor Power Supplies (ISEPS) and the associated HNB diagnostics; the HVD1 is interfaced with a SF6 insulated Transmission Line (connecting the main power supplies to the HNB) through a High Voltage (HV) Bushing Assembly (HVBA) carrying inside ISEPS power conductors and diagnostics. The HVD1 and HVBA are unique devices for size, electrostatic and mechanical features. This paper presents the main design choices adopted to comply with the challenging technical requirements and the supporting electrostatic, seismic and thermal analyses. Finally, next procurement steps and definition of special tests to verify the key design choices are also reported.