A complement to ITER?

The compact fusion reactor that Italy has agreed to help Russia build at a former weapons laboratory outside Moscow will have a “high probability” of attaining ignition, a long-sought threshold where the fusion reaction becomes self-sustaining. So says Bruno Coppi, the MIT physicist who led the design effort of the device known as Ignitor. The reactor will also give scientists an opportunity to work on some basic science problems that need to be resolved if fusion is ever going to become an energy source, he says.

Italian prime minister Silvio Berlusconi and Russian prime minister Vladimir Putin signed an agreement on 26 April for Italy to share the cost of building Ignitor on the Triniti site at the Kurchatov Institute in Troitsk. Coppi says the budget and the construction timetable are not finalized. Stephen Dean, president of the US industry group Fusion Power Associates, describes the pact signed in Milan as an agreement to negotiate the exact terms. He said Ignitor’s small size and strong magnets make it a risky design. Coppi notes that ITER, the giant test reactor being built in Cadarache, France, by a seven-party international collaboration, won’t be capable of ignition; Dean says that fusion power reactors are expected to operate at a high-gain, subignition state, in which some input of energy will be required to sustain the plasma and fusion reactions (see Physics Today, April 2010, page 20 ). Still, Dean says Ignitor, if built, will be useful for experiments that would be more difficult and cumbersome to perform at ITER.