Britain's newest fusion reactor being built by Oxfordshire-based Tokamak Energy has fired up its latest fusion reactor for the first time and aims to reach temperatures of 100m degrees Celsius next year, taking the world one step further towards generating electricity from the power of the stars.
Known as the ST40, the reactor represents the third of five stages in the company’s plan to deliver fusion energy to the grid by 2030. Controlled fusion requires temperatures in excess of 100m°C, but this has never been achieved by a privately funded company. To reach that goal, Tokamak Energy is focusing on compact, spherical Tokamak reactors, as it believes they are quicker to develop and offer the quickest route to commercial fusion power.
Britains first commercial fusion reactor
The heart of the Tokamak ST40 reactor - a super-hot cloud of electrically charged gas, or plasma - is expected to reach a temperature of 100 million centigrade next year. That is how hot it needs to be to trigger fusion, the joining together of atomic nuclei accompanied by an enormous release of energy. The reactor will provide clean energy to the UK's national grid by 2030, according to its creators Tokamak Energy.
“Today is an important day for fusion energy development in the UK, and the world,” said Dr David Kingham, CEO of Tokamak Energy. “We are unveiling the first world-class controlled fusion device to have been designed, built and operated by a private venture. The ST40 is a machine that will show fusion temperatures – 100 million degrees – are possible in compact, cost-effective reactors. This will allow fusion power to be achieved in years, not decades.”
The spherical tokamak is an offshoot of the conventional tokamak design. Proponents claim that it has a number of substantial practical advantages over these devices. For this reason the ST has generated considerable interest since the late 1980s. However, development remains effectively one generation behind traditional tokamak efforts like JET. Major experiments in the ST field include the pioneering START and MAST at Culham in the UK, the US's NSTX-U and Russian Globus-M.
The amount of fusion energy a Spherical Tokamak is capable of producing is a direct result of the number of fusion reactions taking place in its core. Scientists know that the larger the vessel, the larger the volume of the plasma ... and therefore the greater the potential for fusion energy.
The next steps in the ST40’s development will see the reactor’s magnetic coils commissioned and installed. These are crucial for containing the super-heated plasma and pushing towards fusion temperatures. By Autumn 2017, the company hopes to have produced a plasma temperature of 15m°C, with 100m°C reached at some point in 2018. Longer term, Tokamak Energy is aiming to deliver its first fusion electricity by 2025, with commercial power available via the grid five years later.
What is Fusion
Fusion is the energy source of the Sun and stars. In the tremendous heat and gravity at the core of these stellar bodies, hydrogen nuclei collide, fuse into heavier helium atoms and release tremendous amounts of energy in the process.
Twentieth-century fusion science identified the most efficient fusion reaction in the laboratory setting to be the reaction between two hydrogen isotopes, deuterium (D) and tritium (T). The DT fusion reaction produces the highest energy gain at the "lowest" temperatures.
Three conditions must be fulfilled to achieve fusion in a laboratory: very high temperature (on the order of 100,000,000° Celsius); sufficient plasma particle density (to increase the likelihood that collisions do occur); and sufficient confinement time (to hold the plasma, which has a propensity to expand, within a defined volume).
At extreme temperatures, electrons are separated from nuclei and a gas becomes a plasma—often referred to as the fourth state of matter. Fusion plasmas provide the environment in which light elements can fuse and yield energy.
In a Tokamak device, powerful magnetic fields are used to confine and control the plasma.
ITER (International Thermonuclear Experimental Reactor, also Latin for "way") is an international nuclear fusion research and engineering megaproject, which will be the world's largest magnetic confinement plasma physics experiment. It is an experimental tokamak nuclear fusion reactor that is being built next to the Cadarache facility in Saint-Paul-lès-Durance, which is in southern France.
The ITER project aims to make the long-awaited transition from experimental studies of plasma physics to full-scale electricity-producing fusion power stations. The ITER fusion reactor has been designed to produce 500 megawatts of output power for around twenty minutes while needing 50 megawatts to operate.[2] Thereby the machine aims to demonstrate the principle of producing more energy from the fusion process than is used to initiate it, something that has not yet been achieved in any fusion reactor.
Take a tour of the ITER facility