New superconductors raise hope for fast development of compact fusion reactor

Engineers at the Massachusetts Institute of Technology (MIT) have claimed that new commercially-available superconductors could enable them to build an operational nuclear fusion reactor in as little as ten years. Known as an ARC reactor, this would be a small version of the toroidal tokomak reactor type, similar to the large reactor currently being built by international fusion project Iter in southern France.

The ARC reactor — the acronym stands for affordable, robust, compact; although it probably owes something to the fictional power reactor in the Iron Man superhero films and comics — uses rare-earth barium copper oxide (REBCO) tapes to form its magnets. These are claimed to produce a stronger magnetic field than the superconductors used in other tokomak designs (Iter, designed before REBCO became available, uses two superconductors, niobium-tin and niobium-titanium), which in turn means that the fusion reactor can be smaller, about half the size of Iter’s 6m diameter: this means it would also be cheaper and quicker to build. REBCO becomes superconducting at temperatures of around 90-100K, rather than the 4K critical temperature of Iter’s magnets; this means that cooling can be achieved with liquid neon, hydrogen or even nitrogen rather than liquid helium, making cryogenics simpler and cheaper.