US-based General Atomics has started work to build the 1000t central solenoid for the international ITER fusion project.

The component, which will form the backbone of the tokamak, will be one of the most powerful electromagnets ever built. It will have peak field strength of 13.1 Tesla, enough to life an aircraft carrier, GA said.

"The central solenoid represents the heartbeat of ITER, because it pulses the magnets that drive electric current through the Tokamak plasma," said Ned Sauthoff, director of the US ITER Project Office.

The central solenoid will stand 18m high and has a diameter of 4.13m. It will be made up of six modules each wound with 6km of superconducting niobium-tin (Nb3Sn) wire supplied by Japan. General Atomics will manufacture a seventh module as a spare.

Winding operations began on 10 April in California, and are expected to continue until 2017.

Due to its size, the central solenoid will delivered to ITER in segments for assembly on site. Delivery is expected in 2019.

Photo: ITER central solenoid