AbstractThe 1 MV bushing is considered as one of the most technically challenging components of the ITER neutral beam injectors, necessitating the design and manufacture of large ceramic insulators beyond the range of current industrial production. The ITER radiation environment and the fact that the bushing forms part of the tritium barrier demand a component of great reliability and safety. An R&D task has been launched for the fabrication of a prototype bushing based on the SINgle GAP, SINGle APerture (SINGAP) 1 MeV accelerator being developed in the EU. We present the design of this prototype, which is to be tested at Cadarache, and compare it with the SINGAP bushing proposed for the ITER injectors.