Materials World Magazine Author : Eoin Redahan
01 Dec 2014
The idea of nuclear fusion appears otherworldly. Here is a carbon emissions-free process that produces four times more power than nuclear fission. The waste can eventually be disposed of safely, and the fuel sources – deuterium and tritium – are abundant. But after 60 years of nuclear fusion research, are we any closer to the goose that lays the golden eggs?
So far, fusion’s imposing challenge has not been met. For atoms to fuse, a huge amount of energy must be generated. As such, materials must be developed that can withstand hundred of millions of degrees. To create fusion energy, light atomic nuclei are fused within high-pressure, high-temperature plasma, which is contained by a magnetic field. As yet, scientists haven’t refined this magnetic confinement efficiently enough to reach a break-even point – where the energy output equals the energy input.
Certainly, enough money has been ploughed into the cause. Billions of euros have already been spent on just one facility, the International Thermonuclear Experimental Reactor (ITER) in the south of France. The aim of the ITER project, which is funded by the EU, India, Japan, China, Russia, South Korea and the USA, is to prove that nuclear fusion is commercially viable.
However, the goal of having its deuterium-tritium facility operational by 2027 is looking increasingly optimistic. Despite the amount of brains and resources behind the initiative, the project has been undermined by in-squabbling, bureaucracy and delays, not to speak of the technical challenges.
Encouraging noises are being made about several smaller projects. The prize for most impressive looking equipment must go to Sandia Laboratories’ Z machine in Albuquerque, USA (pictured above). According to the researchers, this huge electric pulse generator is progressing in its pursuit of the fusion dream. In September 2014, the team reported significant byproducts of fusion reactions in one of its experiments. Sandia’s approach involves putting fusion fuel inside a tiny metal can and passing a pulse of 19 million amps through it from top to bottom for 100 nanoseconds. The powerful magnetic field created crushes the can inwards at a speed of 70km/second. At the same time, the researchers pre-heat the deuterium fuel with a laser pulse and apply a steady magnetic field, which holds the fusion fuel in place.
By using this method, the team says it has produced significantly more fusion neutrons than previous methods, though there is still a long way to go – 100 times more neutrons will have to be produced to achieve break-even point.
Defence manufacturer Lockheed Martin also caused a stir recently with claims that its compact fusion reactor will be developed and deployed within 10 years. The key to the success of its reactor concept lies in a magnetic bottle that withstands million-degree temperatures while offering 90% size reduction over previous concepts. Apart from stating that the concept ‘takes the best parts of alternative magnetic confinement approaches’, Lockheed has provided few details about how it will succeed where others have struggled.
The question marks surrounding Lockheed’s initiative mirror those of many others. When the boasts subside, will there be proof in the prototype?