First off, power is measured in Watts, or Energy per Unit Time.
1 Watt is classed as 1 Joule of energy over 1 Second. If you compress that 1 Joule down so it lasts 1 nanosecond, then your power jumps to 1 Billion Watts. The trick is that this power only lasts for that 1ns making the average power much smaller, and dependant on how quickly you can repeat the pulses.
The NIF laser is multistaged for various reasons. Initially, ytterbium-doped optical fiber lasers generates low-energy laser pulses (a few nanojoules with a beam diameter of a few micrometers) at about 1.06 microns (near infrared). Fibre lasers were chosen as beam quality at this stage is important and fibre lasers produce some of the best quality beams available. The pulse is then split into 48 beams and carried by optical fibre to 48 seperate preamplifiers that boost the pulse from nanojoules to milijoules and then from milijoules to about 10 Jouls. The amplification is done by flashlamp pumped slabs of glass doped with a particulat meterial, I believe is neodymium.
These 48 10 Joule pulses are then split into four beams each (192) and passed to the main laser system where 192 beamlines amplify the beams twice. Both the amplifiers in this system are also flashlamp pumped phosphate glass doped with neodymium. Some numbers: 7680 flashlamps 6 feet long, 3072 doped glass slabs, each 42kg in weight. 99.9% of the lasers power comes from these amplifiers, with the output being 1.053 microns.
Finaly, the 192 beams need to be converted to ultraviolet light and so some non linear crystals (KTP - potassium dihydrogen phosphate) much like in green laser pointers, are used to first convert some of the 1053nm light to 530nm, then a second identical crystal used to mix both the remaining 1053nm and the 530nm to get 350nm Ultraviolet at about 1.8 Million Jouls in a 3-60 nanosecond pulse. 1800000/.000000003 = 600 Trillion Watts PEAK power.
The following is a little info from the NIF site
http://www.llnl.gov/nif/project/pdf/NIF_Facts.pdf
The Laser System
• The 192 laser beams of NIF will generate
– Apeak power of 500 trillion watts, 1000 times the electric generating power of the United States.
– Apulse energy of 1.8 million joules of ultraviolet light.
– Apulse length of three to twenty billionths of a second.
• Optical components:
– 7500 large optics including 3072 laser glass slabs as well as large lenses, mirrors, and crystals.
– More than 15,000 small optical components.
• Precision optics: total area of 33,000 square feet
(3/4 of an acre). More than 40 times the total precision optical surface in the world’s largest telescope (Keck Observatory, Hawaii).
• Laser beams: 16-inch by 16-inch beams of infrared
laser light (1-micron wavelength). The infrared beams are converted to ultraviolet beams (0.35-micron wavelength) at the target chamber.
• Laser pulse amplification:
– In the master oscillator room, the initial 1 billionth of a joule pulse is amplified 10,000 times, then split into 48 separate laser pulses.
– In the preamplifier module, each of the 48 pulses is further amplified 20 billion times, then split 4 ways to create 192 pulses.
– In the main laser system, each propagated pulse is amplified another 15,000 times.
– Total amplification = 3 quadrillion (3 million billion).
http://www.llnl.gov/nif/project/nifworks_injection.html
There are other animations and fact sheets on the site if you are willing to look around.
