ILMM 18TH NOVEMBER 2016
In 2014 Lockheed Martin, an American Aerospace and Defence company, announced within the next 10 years it would develop a portable nuclear fusion reactor which would produce 100 MW of energy. This fusion reactor would be small enough to fit on the backs of trucks and a single unit could provide enough energy for a city of 100,000 people. The fusion reactor could quite possibly be one of the most important and ground-breaking inventions of all time. Scroll down to see how the design works and where the technology is at the moment.
Overview of nuclear fusion
To understand nuclear fusion we first have to consider nuclear fission, the process used in nuclear power stations. Nuclear fission involves breaking apart nucleus’ by firing high speed neutrons at a target nucleus. The nucleus will break apart into smaller fragments known as fission products. When this occurs, about 0.1% of the mass converts into energy as per Einstein’s equation, E = mc2. Considering the many millions of atoms present in minute volumes, energy productions in nuclear power stations can reach around 12,000 Mega Watt hours per day. Although a proven method of energy production, nuclear fission has disadvantages such as production of nuclear waste and safety concerns.
Nuclear fusion on the other hand reverses this process. Nuclear fusion involves the smashing together of two atomic nuclei at high speeds to form a larger nucleus, releasing energy in the process. It represents a near limitless supply of energy which is safe, clean and self-sustaining. The problem is the complexity of the process, such as the requirements of incredibly high temperatures and the massive electromagnetic forces required.
Conventional Reactors
In existing, conventional designs, the fuel consisting of different hydrogen isotopes is heated to temperatures over 100 million degrees C. At this temperature, the fuel becomes plasma. This plasma is incredibly fragile, any contact with reactor surfaces would cool it. Magnetic confinement systems therefore hold the plasma. The hydrogen isotopes fuse to produce helium and high speed neutrons, releasing energy in the process. The idea is for a commercial fusion power station to generate electricity from the energy carried by neutrons. The neutrons will be slowed down by a blanket of denser materiel surrounding the machine and the heat this will produce will be converted to steam to drive turbines.
There are plenty of successfully operating nuclear fusion reactors, in the form of stars. It is however difficult to replicate the conditions of the Sun on Earth. The incredibly high temperatures have been achieved experimentally, though it had taken far more energy to produce than it actually released.
Lockheed Martin’s Fusion Reactor Design
Lockheed Martin is targeting a design which is quite a lot smaller than the Sun, coming in at roughly the size of a jet engine. In previous unsuccessful designs, magnetic field limited fusion reactions in a torus (a doughnut shape). This led to an enormous energy requirement and therefore tiny energy production abilities.
Lockheed Martin’s stealth technology section Skunk Works are producing a tube-like design, much smaller than conventional fusion reactors. They claim compared to the 5% amount of Plasma that conventional reactors can hold, they can go all the way and hold 100%. This lets the design be 10 times smaller. They are using a magnetic confinement concept which uses aspects from several earlier approaches from the 1960s onwards. These earlier cusp device designs were abandoned due to particle leakage from the magnetic fields leading to the loss of temperature. Skunk works claim they have found a way around this by encapsulating the cusp device in a magnetic field. Any particles that try to escape the cusp device are pushed back round it.
The Development
Skunk Works want to develop a prototype within 5 generations, planned within 5 years of the initial 10 year period, and they have already shown they can achieve this in the lab. This would not be full power generation but would demonstrate that the physics behind the concept would work. There have been skeptics of Skunk Works approach, including the professor of nuclear science at MIT Ian Hutchinson. He claims the type of confinement being developed has already been studied with not much success. However, Lockheed Martin are not a small start-up company. It is one of the world’s major aerospace and defence companies. They would not invest so much in a project without confidence.
The clear need for this technology is in safe and sustainable energy production. As a defence company, Lockheed Martin will be looking to use it in major military applications. One example is as a mobile power plant for fighter jets, providing the required power for directed energy weapons. It could also have spacecraft applications, in sighting a new age of space travel.
Where Is It Now?
Lockheed Martin is continuing to invest in the technology, with the investment entering an advanced stage. Rob Weiss, head of Skunk Works, confirmed the team have achieved ‘initial plasma’, an important early step for the design.