Fueling Up For Fusion: MAST’s Super-X, JET’s Deuterium-Tritium Experiments For ITER, And More

We’ve had nuclear fission reactors in operation all over the world for ages, but nuclear fusion always seems to be a decade or two away. While one cannot predict when we’ll reach the goal of sustained nuclear fusion, the cutting edge in test hardware is advancing at a rapid pace that makes us optimistic. Beginning as soon as this month and extending over a few years, we’re living through a very exciting time for nuclear fusion and plasma physics.

The Mega Ampere Spherical Tokamak (MAST) got a big upgrade to test a new cooled divertor design. JET (Joint European Torus) will be testing the deuterium-tritium fuel mixture that will be powering the ITER (the research project whose name began as an acronym for International Thermonuclear Experimental Reactor but has since been changed to just ITER). And the Wendelstein 7-X stellarator is coming back online with upgraded cooled divertors by next year.

Here the MAST Upgrade’s Super-X divertors have so far shown a ten-fold decrease in the temperature which the divertor is exposed to while carrying thermal energy out of the tokamak reactor. This means a divertor design and ultimately a fusion reactor that will last longer between maintenance sessions. On the stellarator side of things, Wendelstein 7-X’s new divertors may allow it to demonstrate the first continuous operation of a stellarator fusion reactor. Meanwhile, JET’s fuel experiments should allow us to test the deuterium-tritium fuel while ITER is working towards first plasma by 2025.

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Twenty Seconds At 100 Megakelvins

The Korea Superconducting Tokamak Advanced Research (KSTAR) magnetic fusion reactor claimed a new record last month — containing hydrogen plasma at 100 megakelvins for 20 seconds. For reference, the core temperature of the Earth’s Sun is a mere 15 megakelvins, although to be fair, it has been in operation quite a bit longer than 20 seconds.

South Korea is a member of the International Thermonuclear Experimental Reactor (ITER) team, a worldwide project researching the science and engineering of nuclear fusion. One of their contributions to the effort is the KSTAR facility, located in the city of Daejeon in the middle of the country (about 150 km south of Seoul).

It is a tokamak-style fusion research reactor using superconducting magnets to generate a magnetic flux density of 3.5 teslas and a plasma current of 2 megaamperes. These conditions are used to confine and maintain the plasma in what’s called the high-confinement mode, the conditions currently favored for fusion reactor designs. Since it went into operation in 2008, it has been creating increasingly longer and hotter “pulses” of plasma.

For all the impressive numbers, the toroidal reactor itself is not that huge. Its major diameter is only 3.6 meters with a minor diameter of 1 meter. What makes the facility so large is all the supporting equipment. Check out the video below — we really like the techniques they use in this virtual tour to highlight key components of the installation.

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Nuclear Fusion At 100: The Hidden Race For Energy Supremacy

It’s hardly a secret that nuclear fusion has had a rough time when it comes to its image in the media: the miracle power source that is always ‘just ten years away’.  Even if no self-respecting physicist would ever make such a statement, the arrival of commercial nuclear fusion power cannot come quickly enough for many. With the promise of virtually endless, clean energy with no waste, it does truly sound like something from a science-fiction story.

Meanwhile, in the world of non-fiction, generations of scientists have dedicated their careers to understanding better how plasma in a reactor behaves, how to contain it and what types of fuels would work best for a fusion reactor, especially one that has to run continuously, with a net positive energy output. In this regard, 2020 is an exciting year, with the German Wendelstein 7-X stellarator reaching its final configuration, and the Chinese HL-2M tokamak about to fire up.

Join me after the break as I look into what a century of progress in fusion research has brought us and where it will take us next.

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China’s Fusion Reactor Hits Milestone

An experimental fusion reactor built by the Chinese Academy of Science has hit a major milestone. The Experimental Advanced Superconducting Tokamak (EAST) has maintained a plasma pulse for a record 102 seconds at a temperature of 50 million degrees – three times hotter than the core of the sun.

The EAST is a tokamak, or a torus that uses superconducting magnets to compress plasma into a thin ribbon where atoms will fuse and energy will be created. For the last fifty years, most research has been dedicated to the study of tokamaks in producing fusion power, but recently several projects have challenged this idea. The Wendelstein 7-X  stellarator at the Max Planck Institute for Plasma Physics recently saw first plasma and if results go as expected, the stellarator will be the design used in fusion power plants. Tokamaks have shortcomings; they can only be ‘pulsed’, not used continuously, and we haven’t been building tokamaks large enough to produce a net gain in power, anyway.

Other tokamaks currently in development include ITER in France. Theoretically, ITER is large enough to attain a net gain in power at 12.4 meters in diameter. EAST is much smaller, with a diameter of just 3.7 meters. It is impossible for EAST to ever produce a net gain in power, but innovations in the design that include superconducting toroidal and poloidal magnets will surely provide insight into unsolved questions in fusion reactor design.