NBTF

ITER’s most powerful external heating system—neutral beam injection—will be tested in advance of operation at the Neutral Beam Test Facility (NBTF) in Padua, at Consorzio RFX premises. Although neutral beam injection is routinely used for plasma heating in fusion devices, the size of ITER imposes enhanced requirements: particle beams have to be much thicker, for example, and individual particles have to be much faster in order to travel far into the core of the plasma.

The Neutral Beam Test Facility will offer scientists the possibility to investigate challenging physics and technology issues and validate concepts before the neutral beam system is installed on ITER. Neutral beam injection relies on beams of high-speed, high-energy atoms that penetrate into the plasma, initiating collisions and transferring their energy. ITER will be equipped with two heating neutral beam injectors (with a provision of a third injector) and a neutral beam line for diagnostic purposes. The injectors will be capable of operating for up to 3600 seconds, each delivering deuterium beams of 16.5 MW with particle energies of 1 MeV. Their combined heating power—33 MW—represents over half of the external heating required by ITER.

In a 17,500 m² building on the premises of Consorzio RFX, in Padua, two neutral beam test stands are under operation  and construction, respectively:

• SPIDER (Source for the Production of Ions of Deuterium Extracted from a Radio frequency plasma) is an ITER-scale negative ion source designed to achieve all ion source requirements;
• MITICA (Megavolt ITER Injector and Concept Advancement) is a full-size prototype of the 1 MV heating neutral beam injectors, capable of full acceleration voltage and power.