It took only a decade from the first atomic bomb to nuclear fission reactors, which currently provide 15% of world's electrical energy. It's more than half a century since the first hydrogen bomb was experimentally detonated, yet we are away from a fusion reactor. If fusion is the most efficient mode of energy creation, stars are the best fusion reactors as we know it. So making a self sustainable fusion reaction on earth is akin to creating a star on earth. Scientists around the globe have been trying the same for decades with little success, often ridiculed by the public -- "fusion energy is always few decades away."
Will the year 2010 be a true turning point? Given, the history of fusion research, this might seem simply an optimistic consideration. However, if the strong signals from National Ignition Facility (NIF) are of any indication that could be an actual 'star birth' scientific world has been waiting.
The national Ignition Facility (NIF) at Lawrence Livermore National Laboratory, California was dedicated on May 2009. It houses the largest and strongest energy laser on the planet and the facility began firing laser beams onto targets in June 2009. The goal is to fuse isotopes of hydrogen to generate carbon free energy that will feed the electric grids.
There are many challenges to initiate and sustain a thermo nuclear reaction. First of all, a typical deuterium -- tritium fusion needs a temperature above 100 million Kelvin in the absence of gravitational compression. The kind of temperatures at which the matter transforms into its fourth state plasma as it exists in stars. Deuterium, also known as heavy hydrogen is an isotope of hydrogen with one proton and one neutron while tritium another isotope has one proton and two neutrons in its nuclei. Their fusion yields the next higher element in the periodic table -- Helium -- along with the release of tremendous amount of energy.
Secondly, the hot plasma needs to be confined long enough to sustain the fusion reaction. Generally two methods are employed to achieve this. One is the magnetic confinement -- originally designed by the Soviets in 1950s. A doughnut shaped device called tokomak is used to hold the plasma with its intense magnetic field. In fact most of the researchers around world still rely on this technique including -- International Thermonuclear experimental reactor (ITER) which was launched in 2006 as an international collaboration. The construction of ITER -- the world's largest science experiment has been continuing in Cadarache, France.
NIF adopts a different technique in plasma confinement known as inertial confinement and hope to hit the jackpot before ITER does. A powerful beam of 192 lasers are used to heat and compress the fuel pellet of deuterium and tritium quickly so that the imploding pellet keeps the material confined. Thus the inertia of the material is exploited in plasma confinement instead of using an external force. In last November NIF announced that laser beams can be effectively delivered and are capable of creating sufficient energy to drive fuel implosion, an important step toward the ultimate goal of fusion ignition.
On January 27, 2010, National Nuclear Security Administration (NNSA), the umbrella organization under which NIF operates, announced that the scientists have successfully focused a record level of laser energy -- more than 1 mega joule -- to a target in a few billionths of a second. This is about 30 time more than the energy used by any such experiments in the world and this exhibits the capability to create conditions necessary for igniting fusion.
"Breaking the megajoule barrier brings us one step closer to fusion ignition at the National Ignition Facility, and shows the universe of opportunities made possible by one of the largest scientific and engineering challenges of our time," said NNSA Administrator Thomas D'Agostino.
This has certainly brought the NIF close to achieving nuclear fusion later this year as it is expected. In the past, focusing the laser energy effectively on tiny targets was a big challenge. With the mega joule shot scientists are stepping up for another stage. The next step is to ignite fuel capsules that require the fuel to be in a frozen hydrogen layer (at 425 degrees Fahrenheit below zero) before the attempt on the actual fuel. The successful fusion at NIF will be a precursor to LIFE-Laser Inertial Fusion Engine-a hybrid technology of fusion and fission being developed at Lawrence Livermore Lab, which may be years away.
In the era of global warming, the fusion plants have another big advantage to offer. The fusion reaction does not produce any green house gases. Also, the required fuels for fusion -- deuterium can be obtained from water and tritium can be bred in the reactor once it is self sustainable. Finally, the birth of the star on the planet will help us to deviate from the habit of depending on the planet for energy needs, truly a remarkable transition for a civilization.
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