this is interesting.....
After more than a decade of work, US engineers have completed the world's most powerful laser, capable of simulating the energy force of a hydrogen bomb.The federal Energy Department will announce on Tuesday that it has officially certified the National Ignition Facility at the Lawrence Livermore National Laboratory in California, clearing the way for a series of experiments over the next year that eventually is hoped will mimic the heat and pressure found at the centre of the sun.
The facility, the size of a football field, comprises of 192 separate laser beams, each travelling 300m in a one-thousandth of a second to converge simultaneously on a target the size of a pencil eraser.
While the NIF laser is expected to be used for a wide range of high-energy and high-density physics experiments, its primary purpose is to help government physicists ensure the reliability of the nation's nuclear weapons as they become older.
The laser 'will be a cornerstone' of the weapons stewardship program, 'ensuring the continuing reliability of the US nuclear stockpile without underground nuclear testing', Thomas D'Agostino, head of the National Nuclear Security Administration, said in an interview on Monday.
The NNSA, a semi-independent arm of the Energy Department, oversees nuclear weapons programs.
The NIF laser was proposed in the early 1990s, when the project's cost was put at $US700 million ($A1.03 billion). Construction began in 1997. Its early years were marked by setbacks including trouble, eventually overcome, in keeping its critical optics perfectly clean and free of dust.
NIF is expected to ramp up power gradually in a series of experiments over the next year, culminating at a power level in 2010 to achieve what scientists call 'fusion ignition': enough heat and pressure to fuse hydrogen atoms in a tiny cylindrical 'target' so that more energy is released than is generated by the laser beams themselves.
That is what happens when a hydrogen bomb explodes and inside the sun, at its centre. It's also what scientists would one day like to achieve on a continuing basis to produce a clean, safe form of energy by fusing atoms instead of splits them apart.
Edward Moses, director of the NIF project who has led its development since 1999, said he is ever more confident that NIF will achieve 'fusion ignition'.
'It's now operational,' Moses said in a telephone interview. 'The lasers are there. The targets are there, and we've proven the optics. But now the proof is in the shooting. We've got to put all this together and shoot the targets. It's the first time anyone has ever done experiments at this scale.'
NIF's 192 laser beams produce 60 to 70 times more energy than a 60-beam system at the University of Rochester, which is the second most powerful laser, Moses said.
In addition to helping diagnose the functioning of nuclear warheads, the NIF laser is expected to be used in astrophysics, allowing scientists to mimic conditions inside planets and new solar systems.
Moses said he sees NIF as key in the move toward developing a fusion energy source. 'What we want to show is scientific proof of the principle of fusion energy,' said Moses, predicting some experiments for a short time may produce 50 to 100 times more energy than the lasers generate.
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