These tests are one of the most crucial aspects of the whole project to test and develop the ITER neutral beam injector system for plasma heating (NBTF).
We are inside MITICA vacuum vessel where the short circuiting device, installed in 2019, is giving the place to a mock-up of the negative ion source in order to study high voltage in vacuum holding up to 1 MV. It’s an important step, foreseen after the full 1 MV power supply test, successfully carried out in MITICA, in collaboration with colleagues from QST and F4E.
Due to the uncertainties on high voltage behaviour in vacuum, on large distances, an electrostatic mock-up of MITICA ion source has been designed and realized. It will be installed inside the vacuum vessel both to study possible problems of high voltage in vacuum holding and assess solutions before the injector operation.
Supplied by the Italian Fantini Sud SpA, the mock up will act mimicking the electrostatic behaviour of MITICA ion beam source that, once operational, will get the necessary voltage to generate and accelerate the negative ions.
In the ITER HNB injector prototype, the accelerated ion beam will be neutralized before it is injected into the tokamak, passing through the large magnetic fields. Once in the plasma core, the neutral beam will transfer its energy to heat the plasma and allow ITER reach the temperatures for fusion reactions ignition: 150 million degrees.
Some key parameters. ITER main heating system will consist of two neutral beam injectors (NBI), each with 1 MeV power and a deuterium negative ion beam of 40 A, to provide the plasma with about 16,5 MW power for one hour.