For Nuclear Fusion, Could Two Lasers Be Better Than One?

摘要

Doing nuclear fusion research usually means big bucks. The major industrialized nations are about to commit themselves to the $12 billion ITER fusion reactor project, the most expensive experiment ever, and both the United States and France are spending billions of dollars building the most powerful lasers in the world, in part to test another route to fusion. But another strategy has been developing quietly in the wings, one that uses two less powerful lasers instead of one big one. Advocates say that with a little encouragement, it could steal a march on the big facilities and carve a new, cheaper path to fusion. All these approaches share a common principle: When hydrogen nuclei fuse to form helium, they release energy. But getting them to do so requires enormous temperatures and pressures, such as those in the core of the sun. The ITER reactor will use huge superconducting magnets to contain a hydrogen plasma and heat it enough for the nuclei to fuse. Designers are hoping it will produce more energy than is needed to run it.