Pictures: Inside the World's Most Powerful Laser
By Brian Handwerk, National Geographic News, 29 November 2012.
By Brian Handwerk, National Geographic News, 29 November 2012.
Laser "Quantum Leap"
Looking like a portal to a science fiction movie, preamplifiers line a corridor at the U.S. Lawrence Livermore National Laboratory's National Ignition Facility (NIF).
Preamplifiers work by increasing the energy of laser beams - up to ten billion times - before these beams reach the facility's target chamber.
The project's lasers are tackling "one of physics' grand challenges" - igniting hydrogen fusion fuel in the laboratory, according to the NIF website. Nuclear fusion - the merging of the nuclei of two atoms of, say, hydrogen - can result in a tremendous amount of excess energy. Nuclear fission, by contrast, involves the splitting of atoms.
This July, California-based NIF made history by combining 192 laser beams into a record-breaking laser shot that packed over 500 trillion watts of peak power-a thousand times more power than the entire United States uses at any given instant.
"This was a quantum leap for laser technology around the world," NIF director Ed Moses said in September. But some critics of the $5 billion project wonder why the laser has yet to ignite a fusion chain reaction after three-and-a-half years in operation. Supporters counter that such ground-breaking science simply can't be rushed.
Inside the Chamber
What resembles a giant metal nut is actually the NIF's laser target chamber, which was assembled with four-inch-thick (ten-centimetre-thick) aluminium panels capable of handling superpowerful beams.
"We didn't do it just to build the world's biggest laser," Moses explained.
"The intent was to perform our strategic missions. We help to enhance international security...and energy security," he said, as well as "do fundamental science that could not be done anywhere else."
Chamber in Motion
In 1999, during the NIF's construction, the target chamber was carefully hoisted by crane and moved to the target bay (pictured).
Thirteen years later, the facility's 192 laser beams fired off within just a few trillionths of a second of each other onto a 0.08-inch-wide (2-millimetre-wide) target.
Such a feat makes NIF's lasers among the world's most precise.
Getting in Position
Prior to each laser experiment, a "positioner" precisely centres the target inside the target chamber and helps align the laser beams (as pictured in 2008).
Such experiments are part of core NIF missions, including nuclear weapons testing, Moses noted.
"We have the ability to create the conditions that exist in nuclear weapons and make sure that our strategic deterrent is effective without nuclear testing," he said.
"So we support the [global] Comprehensive Nuclear-Test-Ban Treaty. With fusion processes, the high pressures and high temperatures and high densities that exist are completely different than those that exist in a [conventional] lab."
Laser Bays
Each of NIF's two identical laser bays, seen from above, has a utility spine down the middle and 48 beam lines on either side, for a total of 192.
The facility's beam lines - which connect to the target chamber in groups of four - produce laser shots that scientists hope will someday help create waste-free fusion energy.
"Fusion energy is the energy that powers the universe" - for example, via the sun - Moses said.
"We hope to build a fusion engine that makes it possible to work on a very small scale."
Peering Into the Universe
Holes in the target chamber (pictured during construction) provide access for laser beams and viewing ports for diagnostic equipment, which analyzes bits of material blasted by the laser to the extreme densities, temperatures, and pressures found in extreme parts of the universe and deep inside our own planet.
"We look at the things closest by and those farthest away" - from the centre of Earth to the heart of Saturn - Moses said.
For instance, the team found that "iron in the centre of the Earth doesn't look like iron up here. It's under one million times the pressure, and the chemistry going on is much different. That's what gives us the magnetic field in a different way than we might expect if we had pure iron," he said.
Amping It Up
Technicians assemble and align the components in the NIF's preamplifier module, where the laser's newfound power and energy are opening a new world of scientific possibilities.
"The laser was invented 50 years ago, but this new level of capabilities is now only about a year old," Moses said. "Experiments with these kinds of capabilities are just starting up, and we couldn't be more excited about the years ahead."
But at least one deadline has already passed. The National Nuclear Security Administration set a fusion ignition target date of October 1, 2012. With that date come and gone, Energy Secretary Steven Chu must now brief Congress on NIF's failed fusion efforts to date, and help chart the facility's future course of exploration.
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