Nuclear Fusion: Simulation Shows Potential

Experimental nuclear fusion reactor is seen at a laboratory in the Southwest Institute of Physics in Chengdu, Sichuan Province April 15, 2011.

High-gain nuclear fusion could soon be a possibility according to new computer simulations.

A series of computer simulations performed at Sandia National Laboratories revealed that a fusion reactor can release an output of energy that is greater than the energy fed into the reactor.

The method being tested at Sandia appears to be 50 times more efficient to drive implosions of targeted materials to create the fusion reaction.

Nuclear fusion occurs when two atoms fuse together to form a heavier atom. This process releases a vast amount of energy. However nuclear fusion only occurs naturally at incredibly high temperatures like the center of a star.

Even though the process has been impossible to recreate in Earth, scientists have been studying ways to make nuclear fusion possible because nuclear fusion is a very attractive power source since the fuel is free and the process releases massive amounts of energy.

Scientists have looked at two competing approaches for the artificial creation of nuclear fusion: magnetic confinement and inertial confinement.

Magnetic confinement uses magnetic force to contain the fusing plasma within a device while inertial confinement uses lasers to trigger the fusion process.

Magnetic confinement is being used in the 500-megawatt ITER fusion reactor in France while inertial confinement is being used in California's National Ignition Facility.

Magnetic confinement is regarded as the better alternative and according to the computer simulations performed at Sandia the method is more efficient as well.

The researchers at Sandia are testing a method called magnetized inertial fusion in which two coils generate a magnetic field that confines the fusion reaction.

A metal cylinder lines the insides of each of the coils. The cylinder has a metal liner of deuterium and tritium which is then hit with a current of tens of millions of amperes. The current destroys the liner but it generates a strong magnetic field.

"People didn't think there was a high-gain option for magnetized inertial fusion but these numerical simulations show there is," said Sandia researcher Steve Slutz, the paper's lead author. "Now we have to see if nature will let us do it. In principle, we don't know why we can't."

The computer simulations showed that the output was 100 times that of 60 million amperes put into the system. Actual tests are necessary to validate the computer simulations and they are already under way at Sandia. A laboratory result is expected by late 2013.

The work was reported in the January 13 issue of Physical Review Letters and was supported by Sandia's Laboratory Directed Research and Development office and by the National Nuclear Security Administration.

Sam Blackburn: The voice behind Stephen Hawking at 70

Sam Blackburn has been Hawking’s technician since 2006. And for these 5 years, he’s the one responsible for the technology that has allowed Hawking to communicate through a computer and a voice synthesizer by twitching his cheek.

When he was diagnosed with motor neurone disease (or ALS) at 21, physicist Stephen Hawking was only expected to live a few years. He turns 70 this week.

Since about 1986, he’s had to use a menu controlled by a computer system to speak. A computer highlights cells in a big grid of letters or words, and when the correct one is highlighted, he presses a switch.

But when he became unable to move his hands sufficiently, he moved to an infrared system mounted on his glasses, which detects movement in his cheek muscle. His facial muscles are the only ones he can control reasonably well.

When Blackburn first started, the system was breaking all the time. “I’d get calls at 1 o’clock in the morning saying ‘Stephen can’t speak, what do we do?’” he says. “So I needed to modernize the system.”

He did so incrementally, so the learning wouldn’t be too steep. “Stephen wouldn’t be able to ask for help because the very thing he wouldn’t be able to use would be the speech system,” he says. “Understandably that has made him very reluctant to upgrade.”

The only copy of Hawking’s hardware voice synthesizer is contained in a little gray box in Blackburn’s office. The card inside dates back to the 80s, and this particular one contains Hawking’s voice. There’s a processor on it that has a unique program that turns text into speech that sounds like Hawking’s, and they have only two of these cards.

The company that made them went bankrupt and nobody knows how it works any more. Blackburn is trying to reverse engineer it since they can’t just update the system with a new synthesizer.

“The voice is one of the unique things that defines Stephen in my opinion,” he explains. “He could easily change to a voice that was clearer, perhaps more soothing to listen to – less robotic sounding – but it wouldn’t be Stephen’s voice any more.”

However, Hawking’s progressive nerve decay means that his ability to control his cheek muscle is fading.

His rate of speech is down to about one word per minute. And while Blackburn’s been making slight advances in the current technology, they’re gonna have to move on to something new – like eye-tracking or brain scanning systems.

The challenge for Blackburn’s successor: to keep that well-known voice in working order.

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