- Scientists developing a compact version of a nuclear fusion reactor have shown in a series of research papers that it should work,
- Renewing hopes that the long-elusive goal of mimicking the way the sun produces energy might be achieved and eventually contribute to the fight against climate change.
- Construction of a reactor, called Sparc, which is being developed by researchers at the Massachusetts Institute of Technology and a spinoff company, Commonwealth Fusion Systems, is expected to begin next spring and take three or four years.
- World’s largest fusion-power project, a multinational effort in Southern France called ITER, for International Thermonuclear Experimental Reactor.
- That reactor has been under construction since 2013 and, although it is not designed to generate electricity, is expected to produce a fusion reaction by 2035.
- Fusion, in which lightweight atoms are brought together at temperatures of tens of millions of degrees to release energy, has been held out as a way for the world to address the climate-change implications of electricity production.
- Like a conventional nuclear fission power plant that splits atoms, a fusion plant would not burn fossil fuels and would not produce greenhouse-gas emissions.
- But its fuel, usually isotopes of hydrogen, would be far more plentiful than the uranium used in most nuclear plants, and fusion would generate less, and less dangerous, radioactivity and waste than fission plants.
- But the hurdles to building a machine that can create and control a fusion plasma — a roiling ultrahot cloud of atoms that will damage or destroy anything it touches — are enormous.
- Sparc employs the same kind of device as ITER: a tokamak, or doughnut-shaped chamber inside which the fusion reaction takes place.
- Because the plasma cloud is so hot — hotter than the sun — it must be confined by magnetic forces.
- ITER does this using huge electromagnetic coils that contain superconducting wires that must be cooled by liquid helium.