Giant Laser in the Works to Achieve Fusion

July 15, 2008 -- In the movie "Spiderman II," the web-slinging hero stops the creation of a tritium-fueled laser fusion machine. Doctor Octopus's theory was right, but his machine was too small.

Scientists at the Lawrence Livermore National Laboratory in California are building their own laser fusion machine that is 10 stories tall, 400 feet long and fueled with tritium (and deuterium).

The goal of the project, known as the National Ignition Facility (NIF), is to create such intense heat and pressure that the fuel, both isotopes of the element hydrogen, will fuse together to form helium.

Researchers expect that reaction will release massive amounts of energy that could one day provide nearly unlimited and environmentally friendly power to the world, advance basic scientific research and ensure the effectiveness of the nation's nuclear warheads.

"It is absolutely essential that we try this," said Richard Petrasso of the Massachusetts Institute of Technology's Plasma Science and Fusion Center who is also working on the NIF.

"If we can in fact achieve fusion and make copious amounts of energy, that would be a clear achievement."

To achieve nuclear fusion, scientists will cool samples of deuterium and tritium -- two isotopes of the element hydrogen that have extra neutrons -- to just above absolute zero in a glass-capped cylinder about the size of a quarter.

Then 192 laser beams, split into two groups, will shine onto the fuel, heating it up to about the point of ignition.

Some of the energy will explode outwards, but some of the energy will further compress the innermost core of the fuel, compressing it so much that two hydrogen atoms will fuse together and create one helium atom.

Nuclear ignition, as Petrasso explains, is like a smoldering log suddenly bursting into flames.

"Once you reach certain conditions of pressure and temperature that log will spontaneously start to burn," said Petrasso. "But the fuel for NIF is nuclear, not chemical, and because of that we will get much more energy."

That reaction powers and creates similar, but controlled conditions found in huge supernovae many times the size of the sun and thermonuclear warheads, both of which will also be research focuses at the NIF, said Bob Hirschfeld, also at the NIF.

Since exploding nuclear warheads both above and below ground is now forbidden, the military has a difficult time telling if its stockpile of nuclear weapons works.