A view of a cryogenically cooled National Ignition Facility (NIF) target as "seen" by the laser through the hohlraum's laser entrance hole. | Photo courtesy of Lawrence Livermore National Laboratory.
These are exciting times for fusion energy. Today I’m sharing that excitement with several hundred scientists at a conference on Inertial Fusion Science Applications in Bordeaux, France. These scientists, along with scientists and others around the world, have shown great interest in our National Ignition Facility (NIF) at Lawrence Livermore National Lab, where experiments are seeking to harness the same energy that powers the stars. These experiments have a wide range of scientific applications, ranging from astrophysics to material science, to laser medical therapy and hazardous waste treatment. They also improve our understanding of nuclear weapons and may be the first steps toward a new source of clean energy.
NIF is one of the world’s most complex engineering accomplishments, the result of more than 50 years of research and development. It uses 192 laser beams to collapse and heat a sphere of hydrogen fuel only millimeters wide. Within a few billionths of a second, the nuclei in the hot, dense center react to release a tiny burst of nuclear energy. The right conditions in the rest of the collapsed capsule can capture enough of that energy to “ignite” the rest of the fuel.
The NIF laser, targets, and diagnostics are marvelous technology and they have produced extraordinary results since megajoule-level laser shots began about a year ago – new science, new weapons insights, and good progress toward ignition. While capsules have been imploded to about 1/30th of their original size with adequate high temperatures, the overall capsule conditions are currently only a few percent of the temperature that is required for ignition. “Tuning” of the laser drive and target properties may get us there within the next year, but it is possible that it could take more time. Laboratory fusion is not easy, as many have long noted. However, the people at NIF are tackling the challenge, and excitement is growing with every laser shot.
We must reach ignition to have any serious discussion of inertial fusion as an energy source. Even then, several technology advances beyond ignition will be necessary, but they are possible. The National Academy of Sciences is currently studying the viability of various inertial fusion energy concepts. Their report, expected within a year, together with the achievement of ignition at NIF, will help the U.S. government and its international partners better understand the potential for inertial fusion energy -- and whether we can one day achieve it.