You can accuse fusion power advocates of being overly optimistic but never of thinking small. Fusion occurs when two elements combine, or “fuse,” together to form a new, third element, converting matter to energy. It is the process that powers the sun, and the fusion world’s marquee projects are accordingly grand. Consider the International Thermonuclear Experimental Reactor (ITER), which a consortium of seven nations is building in France. This $21-billion tokomak reactor will use superconducting magnets to create plasma hot and dense enough to achieve fusion. When finished, ITER will weigh 23,000 metric tons, three times the weight of the Eiffel Tower. The National Ignition Facility (NIF), its main competitor, is equally complex: it fires 192 lasers at a fuel pellet until it is subjected to temperatures of 50 million degrees Celsius and pressures of 150 billion atmospheres.
Despite all this, a working fusion power plant based on ITER or NIF remains decades away. A new crop of researchers are pursuing a different strategy: going small. This year the U.S. Advanced Research Projects Agency–Energy invested nearly $30 million in nine smaller projects aimed at affordable fusion through a program called Accelerating Low-Cost Plasma Heating and Assembly (ALPHA). One representative project, run by Tustin, Calif.–based company Magneto-Inertial Fusion Technologies, is designed to “pinch” a plasma with an electric current until it compresses itself enough induce fusion.