In 1945, the United States exploded the first atomic bomb
and, by the mid-1950s, commercial power plants based on nuclear fission were already under construction. By contrast, the U.S. exploded the
first hydrogen bomb in 1953, but 56 years later nuclear fusion power
plants are still decades away.
What’s the difference? The difference is that controlled
replication of the conditions in the sun, necessary for a fusion power plant,
is far more difficult than simply bringing enough radioactive material together
to sustain a controlled fission chain-reaction.
Until now, most of the billions of dollars put into
controlled fusion research have been directed toward so-called magnetic confinement,
which uses magnetic fields to heat and contain a dense plasma containing the
hydrogen isotopes tritium and deuterium. On the cutting edge of this effort is
the internationally-funded ITER project being built in France. That facility
won’t be ready until 2018. Even if ITER meets its goals, magnetic confinement
is not likely to lead to commercial fusion power plants in less than 30 years.
On the other hand, a dark-horse competitor, called inertial
confinement, has been hiding in the shadows for about 35 years. Inertial
confinement involves striking a tiny deuterium-tritium target with a laser beam
so intense that the target implodes, and for a tiny fraction of a second
becomes as hot and dense as the center of the sun. The result is a tiny fusion
reaction that converts some of the mass of the target directly to energy.
Today, the leading edge of inertial confinement research is
centered at the National Ignition Facility (NIF), located at the Lawrence
Livermore National Laboratory. It is a sprawling complex that was funded back
in 1997 to do one job: Combine hydrogen nuclei to create helium with a net
release of more energy than it takes to trigger the inertial confinement
process.
The $3.5 billion facility was originally conceived to help
study nuclear weapons effects and to do basic research on what powers stars.
But more and more, its emphasis has shifted toward proving the viability of
controlled fusion as a source of energy.
The fusion reaction at NIF will involve hydrogen isotopes
inside a gold capsule no larger than a pencil eraser. It contains a total of
192 super...
