UC Taps Star Power
Scientists for decades have been hunting for ways to harness the enormous force of the sun and stars to supply energy here on Earth. The National Ignition Facility at the Lawrence Livermore Laboratory may spark the light at the end of the tunnel.
The 10-story building, roughly the size of three football fields, houses the world's largest, most powerful laser. The 192 laser beams inside were designed to aim massive amounts of energy at a pea-sized hydrogen pellet. In turn, the pellet will produce and release 10 times the power, or more, than the amount injected by the laser.
That's the hope. And if the scientists and engineers can turn theory into practice, they will create a nuclear fusion engine. Nuclear fusion is the reaction that gives the sun and stars their immense power, and it drives most of the energy in the universe.
Jeff Wisoff, deputy principal associate director, National Ignition Facility and Photon Science
Mimicking and controlling the highly volatile process – tantamount to creating a star in a laboratory – could lead to ways to produce plentiful clean and safe energy.
Controlling and exploiting this fusion process can reap huge benefits at a time when fossil fuel supplies are shrinking and fears about global warming are forcing governments to seek new sources of energy.
"Mother Nature powers the stars with fusion energy," says Jeff Wisoff, deputy principal associate director of NIF and Photon Science. "It's a limitless supply. It is a carbon-free supply of energy and the natural resource that is needed is very abundant on Earth. And so it's a natural fit for going forward and sustaining a worldwide economy on fusion energy by harnessing this power."
Applying the Research
The National Ignition Facility, with the world's largest laser, was designed to produce extraordinarily high temperatures and pressures and achieve nuclear fusion in a safe laboratory setting.
These conditions – tens of millions of degrees and pressures many billions of times greater than Earth’s atmosphere – now exist only in the cores of stars and planets and in nuclear weapons.
And while demonstrating nuclear fusion as a viable means for abundant clean energy may be the most exciting offshoot of NIF research, another of its roles is to study the conditions associated with the inner workings of nuclear weapons.
The NIF is a cornerstone of a critical national security mission to ensure the reliability and safety of the U.S. nuclear stockpile without conducting underground testing. At NIF, scientists will be able to provide data for supercomputer simulations so that conditions that exist inside a thermonuclear weapon can be replicated without blowing anything up.
NIF experiments will also help scientists who are trying to understand the universe in many fundamental ways, including astrophysicists learning about the hot, dense interiors of large planets, stars and other phenomena.
Indeed, the primary fuel for nuclear fusion is hydrogen, which is abundant in water. And fusion energy is relatively clean because it produces very little long-lived hazardous waste.
However, a successful laboratory formula for nuclear fusion has been elusive, and some skeptics don't believe that this suggested solution to the world's energy woes is in the foreseeable future.
Igniting a new energy era
Edward Moses, who heads the ignition facility, is a leader in the development of an energy production concept known as LIFE, which stands for laser inertial fusion engine. Moses is optimistic the laser system can generate abundant carbon-free electricity using water and even nuclear waste as fuel.
"An aggressive development of this technology could lead to a LIFE pilot generation plant in the 2020 timeframe followed by commercial deployment in the following 10 years," Moses says.
In 2010, the NIF will begin focusing the full energy of its lasers on its targets with the hope of achieving fusion and igniting the world's first controlled thermonuclear reaction with energy gain within two years. But these will not be shots in the dark.
For the last 12 years, thousands of workers have been piecing together and fine-tuning the millions of delicate parts that define the facility. The NIF will continue testing its lasers even more in coming months to increase their power and precision. This winter, it reinforced its title as the highest-energy laser in the world when it delivered 1.1 million joules of ultraviolet energy – enough to light 10,000 100-watt light bulbs for one second – to the center of its target chamber. But NIF is ramping up to increase the lasers' power to eventually achieve ignition.
"It's a very methodical science campaign," says Wisoff. "We start out at lower energies, work our way up to higher energies. Through a series of experiments, we want to tune up the parameters to get ignition."
How to make a star
Creating a star begins with tiny lasers that zip through a maze of almost 5,000 feet of special mirrors, fiber optics, crystals and light amplifiers to its target. The lasers bounce back and forth, passing through special glass, building more power along the way. From beginning to end, the total infrared energy of the 192 laser beams grows from one-billionth of a joule to four million joules, a factor of more than a quadrillion – and it all happens in about five-millionths of a second, or millions of times quicker than a blink of an eye.
At peak power the lasers generate 500 trillion watts, which is 500 times the peak electric generating power of the entire United States. A NIF brochure compares the lasers' pointing accuracy to standing on the mound at AT&T Park in San Francisco and throwing a strike at Dodger Stadium, 380 miles away in Los Angeles.
The process of firing the laser is so intricate, yet precise, that it requires 60,000 points of control. Laser shots are triggered and monitored from a NIF control room, which not coincidentally, looks like NASA's.
"It was actually modeled after the concept of a NASA control room," says Wisoff, a former astronaut and veteran of four Space Shuttle flights. "The difference is instead of sending people into space, we're going to bring the stars to Earth."
Fusion vs. Fission
Fusion energy, which NIF will attempt to demonstrate, differs from fission energy.
Within atoms of any element, smaller particles in the nucleus (neutrons and protons) are held together by binding energy. When nuclei are fused together (nuclear fusion) or split apart (nuclear fission), the rearrangement of those particles releases large amounts of binding energy.
The nuclear power plants around the world today utilize fission, or the splitting of heavy atoms such as uranium, to release energy for electricity. They also leave behind unusable strontium-90 and other radioactive waste.
A fusion power plant, on the other hand, will generate energy by fusing atoms of two isotopes of hydrogen, the lightest element. A fusion power plant could produce no greenhouse gas emissions, operate continuously to meet demand, and produce shorter-lived and less hazardous radioactive byproducts than current fission power plants. And because hydrogen is so abundant, the fuel could be simple seawater.
When NIF takes its much anticipated shot at ignition, the lasers will be guided to the center of its aluminum and concrete-coated target chamber, a more than 30 feet in diameter sphere that looks part spaceship and giant golf ball. The lasers will focus on a gold cylinder, about the size of a pencil eraser, which houses a tiny pellet made up of two isotopes of hydrogen (deuterium and tritium).
When the lasers zap the target, and if all goes well, the isotopes will compress, heat up to temperatures of up to 100 million degrees Celsius, and finally fuse into helium, releasing a split-second wallop of energy – the kind of reaction and power that takes place in the center of the sun and stars.
The result should be a burst in the target chamber that will produce 10 to 100 times the laser energy needed to create it. And this "energy gain" is what is sought in fusion research. It is Einstein's E=mc² – unleashing tremendous amounts of energy from tiny amounts of mass.
While operational nuclear fusion power plants may still be a couple decades away, the NIF is laying the groundwork for an Earth-saving solution. Wisoff likens the potential discoveries at NIF to the Wright brothers' pioneering the era of flight.
"This will be ushering in the era of fusion energy," says Wisoff. "I think in the future, people will look back at this point in time and say the National Ignition Facility was when humanity mastered the power that powers the universe."