US finds new love of fusion

At a time when the United States is widely condemned as being unilateralist, there's good news in its foreign affairs. America is rejoining the international project to control thermonuclear fusion - the power source of the stars - to make electricity here on Earth.

By 1998, Canada, the European Union, Japan, and the US had each spent several hundred million dollars on plans for a project in which, working along with Russia, they would build an International Thermonuclear Experimental Reactor (ITER). The US considered the projected $10 billion cost and the project construction plan unrealistic. Congress forced the US team to pick up its marbles and go home.

Since then, the other ITER partners have redesigned the machine and cut its projected cost in half. A US Department of Energy study has called that estimate "credible" and the projected 10-year construction schedule "generally reasonable." ITER has become what President Bush now calls "an incredibly important project to be part of." China, which has reached the same conclusion, is also joining the project at this time.

The US reconciliation comes at a crucial time for ITER. The partners are ready to pick a site and start machine construction. Canada, Japan, and Spain each want to host the facility. If the US is to benefit from this research, it must get back into the game now.

This also is a critical time for the long - and sometimes quixotic - quest to harness fusion power. Energy is released when hydrogen atoms are crushed together strongly enough for the nuclei to fuse. Stars do this easily, thanks to the enormous pressures and temperatures in their cores. On Earth, some fusion scientists use laser beams to crush hydrogen fuel pellets. ITER takes another tack: Its machine will use magnetic fields to confine low pressure hydrogen fuel in a doughnut-shaped tube while heating the fuel to many tens of millions of degrees.

Scientists have pursued magnetic fusion for half a century with many frustrating results. Its hot electrically charged particles refuse to stay put while the gas writhes like a recalcitrant snake or otherwise escapes magnetic confinement. This has made magnetic fusion a receding goal. That situation has changed. As Richard Hazeltine at the University of Texas in Austin and Stewart Prager at the University of Wisconsin, Madison, have explained in an overview article in Physics Today that progress in understanding many of these confinement problems has been substantial and, in some cases, "revolutionary." They conclude that magnetic fusion is poised for significant progress and ITER is a machine well suited to do the job.

The US now spends some $250 million a year on fusion research. It is ready to commit around $50 million annually to the $5 billion ITER project - down from $80 million a year before its 1998 walkout. Bush calls it an "opportunity to blaze new paths," which "makes sense for America."

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