Updated electrical design of the Diagnostic Neutral Beam Injector in RFX-mod2

Abstract

The Diagnostic Neutral Beam Injector (DNBI) of the RFX-mod2 experiment (Consorzio RFX, Padova) is expected to provide novel and significant information about the Reversed Field Pinch confinement of fusion plasmas. The present DNBI, built by the Budker Institute of Plasma Physics, features an arc discharge H+ source, coupled to a 4-grid 50 keV acceleration system, to produce a 50 ms, 5 A ion beam. This contribution presents the latest upgrades of the DNBI. The High Voltage Deck (HVD) was completely restructured, and the power transfer was simplified to a single phase insulation transformer. The 50 kV distribution circuit was modernized and made safer against breakdowns. Several custom power supplies in the HVD were designed and procured; their electronic boards were developed to be multipurpose in the DNBI, simplifying the system and improving its maintainability. The features of the magnetic insulation power supply and gas valve power supplies are presented in detail. Finally, the new PLC control system was improved for better protection of the CPU against overvoltages and for better scalability and maintainability of the system.