Another breakthrough made in fusion research – the W7-X stellarator


Close on the heels of the recent breakthroughs in nuclear fusion technology, in the process of the global search for carbon free sources of power aimed at reversing the deadly phenomena of global warming and climate change, news comes of another major advance in this area in the form of the Wendelstein 7-X (W7-X) – the world’s largest stellarator being experimented with at the Max Planck Institute for Plasma Physics in Germany. 

The Wendelstein 7-X stellarator is a magnetic confinement fusion device that relies primarily on external magnets to confine a plasma, and is designed to serve as an alternative to the “tokamak” (derived from the Russian words for “toroidal magnetic confinement”) reactor like the International Thermonuclear Experimental Reactor (ITER) currently being assembled in France as a collaborative effort by 35 countries to replicate the fusion power of the sun in order to enable generation of clean unlimited energy.  

The stellarator is an inherently stable reactor able to operate the plasma in a steady state for greater lengths of time than the tokamak. Although the W7-X will not produce energy, its potential to operate in a continuous mode will be essential for the commercial operation of a fusion reactor. 

Stellarators are distinct from the symmetrical tokamak fusion reactors in being giant complex structures full of twists and turns that subject streams of plasma to extreme temperature and pressure, forcing atoms to collide and fuse together to produce gigantic amounts of energy. The W7-X reactor uses a series of 50 superconducting magnetic coils to confine the plasma as it loops around a twisting and turning circular chamber.  

After producing its first plasma in 2015, physicists working on the W7-X project set new records in 2018 for energy density and plasma confinement for a fusion reactor of this type. Their experiments saw the plasma heated to temperatures of 20 million degrees Celsius, exceeding, thus, the Sun’s temperature of 15 million degrees Celsius.  

The latest breakthrough in fusion research comes with researchers at the Max Planck Institute reporting earlier this month that the W7-X device is capable of confining heat that reaches temperatures twice as great as the core of the sun. 

In designing the W7-X, the researchers set out to address one limitation that affects stellarator designs far more than tokamaks – a type of heat loss known as “neoclassical transport.” This occurs as collisions between the heated particles throw some of these out of their orbit and cause them to drift out and away from the magnetic field. According to the scientists working on the project, the latest results on reducing heat loss, or “neoclassical transport”, mark a step toward enabling stellarators based on the W7-X design to lead to a practical fusion reactor. 

The W7-X is currently undergoing upgrades to install a water-cooling system that will lengthen fusion experiments and will reopen next year.  The upgrades are designed to enable the next step in W7-X research of the worthiness of optimised stellarators to become blueprints for commercial power plants.  

Among the recent breakthroughs in fusion technology include that by the state-run Lawrence Livermore National Laboratory in the US, where researchers focused 192 giant lasers at the National Ignition Facility to heat a tiny fuel pellet, resulting in the release of 1.3 megajoules of energy in 100 trillionths of a second.    

Last month, Washington (US)-based private firm Helion Energy announced it has broken ground on a new facility which will house its seventh generation fusion prototype named Polaris. Construction of the plant in Everett, which will also produce Helium-3 fuel, is expected to be completed in 2022. A Helion release said it is developing a cost-effective, zero-carbon electrical power plant using its pulsed, non-ignition fusion technology. The company said that its fusion power plant will provide “flexible, scalable, baseload power that is affordable, providing the world a new path to full decarbonisation of electricity generation”. 

The most ambitious experiment in this area kicked off last year with the machine assembly of the ITER, or the world’s largest nuclear fusion project, starting in Cadarache, France on July 28, and the first ultra-hot plasma is expected to be generated in late 2025. The world’s largest science project is intended to demonstrate that fusion power can be generated on a commercial scale. ITER’s realising of a self-heating plasma is expected to generate 10 times more heat than is put in. Fusion provides clean, reliable energy without carbon emissions, with miniscule amounts of fuel and no physical possibility of a core meltdown. The fuel for fusion is found in seawater and lithium, which is abundant enough to supply the world for millions of years.