Superlaser Begins Key Experiments

Dan is a deputy news editor for Science.

Lawrence Livermore National Laboratory (LLNL) announced this week that testing time is over: the lab's National Ignition Facility (NIF), the highest energy laser in the world, has fired its first shot at a capsule containing fusion fuel. The aim is to show that by using lasers to compress and heat the tiny peppercorn-sized capsule to conditions more severe than in the center of the sun, they can get the hydrogen fuel to fuse and release large amounts of energy. Such a process, if successful, could form the basis of a future energy-producing reactor.

NIF is a massive laser system the size of several football fields. Its primary goal is to carry out nuclear reactions that can help verify the effectiveness of the United States's nuclear arsenal. But first LLNL is giving NIF the chance to have at shot at ignition, a self-sustaining fusion burn that produces more energy than was pumped in to make it happen. This is a long-sought goal of fusion scientists and would be a major breakthrough in the decades-long search for fusion power.

In this first shot, researchers trained all of NIF's 192 beams onto the target depositing a total of 1 million joules of heat—just over half of NIF's maximum energy. To produce power, the target capsule would normally contain a mixture of cryogenically frozen deuterium and tritium—two isotopes of hydrogen. But in this first shot the capsule also contained some normal hydrogen to dampen down any fusion reaction. This is so researchers can learn more about the physics of the capsule compression before making a full shot at ignition.

LLNL has funding for several years to work on ignition. Although this first shot is a milestone, NIF's proponents say that it may take a year or more before a successful ignition shot is achieved. Others question whether the machine will work at all.

Posted in Physics