ITER Neutral Beam Test Facility

[1] The facility will host the full-scale prototype of the reactor's neutral beam injector, MITICA (Megavolt ITer Injector & Concept Advancement), and a smaller prototype of its ion source, SPIDER (Source for the Production of Ions of Deuterium Extracted from a Radio frequency plasma).

To deliver power to the fusion plasma in ITER, two heating neutral beam injectors will be installed.

They are designed to provide the power of 17 MW each, through the 23 m beamlines, up to the four-meter diameter container: in order to deposit sufficient heating power in the plasma core instead of the plasma edges, the beam particle energy shall be about 1 MeV, thus increasing the neutral beam system complexity to an unprecedented level.

Due to its low conversion efficiency, the neutral beam injector first needs to start a precursor negative ion beam of 40 A, and then neutralizes it by passing it through a gas cell (with an efficiency < 60%), and then by a residual ion dump (the remaining 40—20% negative, 20% positive).

The capabilities of SPIDER and MITICA are listed in the following table in comparison with the objectives of the ITER Heating Neutral Beam and with other existing devices based on RF-driven sources.

View of the Neutral Beam Test Facility
Inside view of the neutral beam test facility; picture taken from the top of MITICA bioshield, during the maintenance of SPIDER (reassembly of SPIDER ongoing in the working area at the center of the picture)
Negative ion extraction with reduced number of beamlets, in early volume operation of SPIDER (May/June 2019)