First set of gyrotrons soon to be installed
Like soup in a microwave oven, the ITER plasma will be heated¹ by electromagnetic waves at frequencies that increase the velocity of the particles, and hence the plasma’s temperature. But contrary to a microwave oven, which targets water molecules, the ITER radiowave heating systems will focus on two different particles: electrons (through electron cyclotron resonance heating) and ions (through ion-cyclotron resonance heating).
Originally, both systems were meant to be hosted in the Radiofrequency Building, a 50-metre-long, three-storey structure abutting the ITER Assembly Hall. Heating power requirements, stemming from the new baseline and its more robust Research Plan, have resulted in the Radiofrequency Building being devoted exclusively to equipment for the electron cyclotron system, while another building, located to the southwest of the Assembly Hall, will be erected to house the ion cyclotron system.
The Radiofrequency Building, whose construction began in 2016, was recently handed over to the ITER Organization by the European Domestic Agency Fusion for Energy. On the two first floors, in the building’s south side, power supplies and current stabilizers procured by Europe and India, as well as ancillaries from Japan will soon be ready for high voltage commissioning. On the third floor, under an agreement with the Russian Domestic Agency, a small team of technicians from GYCOM, the gyrotron manufacturer, is at work installing cubicles and preparing the support structures and ancillaries for the first set of Russian gyrotrons.
On Friday 15 November, the GYCOM workers on the third floor and the ITER team responsible for equipment installation received the visit of Russian Ambassador to France Alexey Meshkov. In this environment which epitomizes the ITER collaboration, with equipment coming from Europe, Japan, India, Russia and the United States, the Ambassador was impressed and praised “the international team, all the different languages I have heard spoken and everyone understanding each other through a common one…”
Procured by Russia (8), Japan (8), Europe (6) and India (2), there will be a total of 24 gyrotrons installed on the south side of the Radiofrequency Building. Commissioning is set to begin in 2025
An equivalent number will be installed in the north side at a later stage, and still more gyrotrons will be needed to deliver the electron cyclotron resonance power required by the new scientific program of the ITER tokamak.
¹Radiowave heating is but one of the ITER plasma heating systems. Neutral beam injection will also contribute to bringing the plasma to the temperature at which fusion reactions can occur (~ 150 million degrees Celsius).