Can We Ever Achieve Fusion Power?

June 29, 2024 by Jenny List 51 Comments

Fusion power has long held the promise of delivering near-endless energy without as many unfortunate side effects as nuclear fission. But despite huge investment and some fascinating science, the old adage about practical power generation being 20 years away seems just as true as ever. But is that really the case? [Brian Potter] has written a review article for Construction Physics, which takes us through the decades of fusion research.

For a start, it’s fascinating to learn about the many historical fusion process, the magnetic pinch, the stelarator, and finally the basis of many modern reactors, the tokamak. He demonstrates that we’ve made an impressive amount of progress, but at the same time warns against misleading comparisons. There’s a graph comparing fusion progress with Moore’s Law that he debunks, but he ends on a positive note. Who knows, we might not need a Mr. Fusion to arrive from the future after all!

Fusion reactors are surprisingly easy to make, assuming you don’t mind putting far more energy in than you’d ever receive in return. We’ve featured more than one Farnsworth fusor over the years.

Nuclear Fusion R&D In 2024: Getting Down To The Gritty Details

May 22, 2024 by Maya Posch 42 Comments

To those who have kept tabs on nuclear fusion research the past decades beyond the articles and soundbites in news outlets, it’s probably clear just how much progress has been made, and how many challenges still remain. Yet since not that many people are into plasma physics, every measure of progress, such as most recently by the South Korean KSTAR (Korea Superconducting Tokamak Advanced Research) tokamak, is met generally by dismissive statements about nuclear fusion always being a certain number of decades away. Looking beyond this in coverage such as the article by Science Alert about this achievement by KSTAR we can however see quite a few of these remaining challenges being touched upon.

Recently KSTAR managed to generate 100 million degrees C plasma and maintain this for 48 seconds, a significant boost over its previous record from 2021 of 30 seconds, partially due to the new divertors that were installed. These divertors are essential for removing impurities from the plasma, yet much like the inner wall of the reactor vessel, these plasma-facing materials (PFM) bear the brunt of the super-hot plasma and any plasma instabilities, as well as the constant neutron flux from the fusion products. KSTAR now features tungsten divertors, which has become a popular material choice for this component.

Researching the optimal PFMs, as well as plasma containment modes and methods to suppress plasma instabilities are just some of the challenges that form the road still ahead before commercial fusion can commence.

Continue reading “Nuclear Fusion R&D In 2024: Getting Down To The Gritty Details” →

You Got Fusion In My Coal Plant!

February 24, 2024 by Navarre Bartz 48 Comments

While coal was predominant in the past for energy generation, plants are shutting down worldwide to improve air quality and because they aren’t cost-competitive. It’s possible that idle infrastructure could be put to good use with fusion instead.

While we’ve yet to see a fusion reactor capable of generating electricity, Type One Energy, the Tennessee Valley Authority, and Oak Ridge National Lab have announced they’re evaluating the recently-closed Bull Run Fossil Plant in Oak Ridge, Tennessee as a site for a nuclear fusion reactor. One of the main advantages for siting any new generation source on top of an old one is the ability to reuse the existing transmission infrastructure to get any generated power to the grid.

Don’t get too excited as it sounds like this is yet another prototype reactor that will be the proof-of-concept before construction of a reactor that can produce commercial power for the grid. While ambitious, the amount of investment by government entities like the Department of Energy and the state of Tennessee (>$55 million) seems to indicate they aren’t just blowing smoke.

If any of this seems familiar, you might be thinking of the Department of Energy’s report on placing advanced fission reactors on old coal sites. A little fuzzy on the difference between a stellarator and a tokamak? Checkout this explainer on some of the different ways to (non-explosively) do fusion on Earth.

NIF’s Laser Fusion Experiment’s Energy Gain Passes Peer Review

February 9, 2024 by Maya Posch 53 Comments

Back in December of 2022, a team of researchers at the USA’s National Ignition Facility (NIF) announced that they had exceeded ‘scientific breakeven’ with their laser-based inertial confinement fusion (ICF) system. Their work has now been peer-reviewed and passed scrutiny, confirming that the energy put into fusing a small amount of deuterium-tritium fuel resulted in a net gain (Q) of 1.5.

Laser Bay 2, one of NIF's two laser bays — Laser Bay 2 at the NIF.

The key take-away here of course remains that ICF is not a viable method of producing energy, as we detailed back in 2021 when we covered the 1.3 MJ yield announcement, and again in 2022 following the subject of this now completed peer review. The sheer amount of energy required to produce the laser energy targeting the fuel capsule and loss therein, as well as the energy required to manufacture each of these fuel capsules (Hohlraum) and sustaining a cycle make it a highly impractical proposition for anything except weapons research.

Despite this, it’s good to see that the NIF’s ICF research is bearing fruit, even if for energy production we should look towards magnetic confinement fusion (MCF), which includes the many tokamaks active today like Japan’s JT-60SE, as well as stellarators like Germany’s Wendelstein 7-X and other efforts to make MCF a major clean-energy source for the future.

UK’s JET Tokamak Retires After 40 Years And 105,842 Pulses

December 23, 2023 by Maya Posch 20 Comments

The UK’s most famous fusion reactor – the Joint European Torus (JET) tokamak – saw its first plasma on June 25th of 1983. Its final plasma pulse was generated on December 18th of 2023, for a total of 105,842 pulses over forty-and-a-half years and countless experiments.

Comparison of toroidal field (TF) coils from JET, JT-60SA and ITER (Credit: QST)

Originally designed in the 1970s by Euratom members, JET formed the core of Europe’s fusion research program, allowing many of the aspects of tokamak systems to be explored, including deuterium-tritium fusion. Its final day of experiments involved an inverted plasma shape prior to targeting electrons at the tokamak’s inner wall, to study the impact of such damage.

Although JET has received a number of upgrades over the decades, the MAST Upgrade and upcoming STEP fusion reactors at the Culham Centre for Fusion Energy (CCFE) are now headed where JET’s design cannot go. Current advanced tokamak reactors like Japan’s JT-60SA are increasingly using super-conducting coils with often plasma volumes far beyond JET’s, with the focus shifting from plasma research to net energy production.

This means that unless JET somehow gets repurposed/upgraded and recommissioned, this is the final goodbye to one of the world’s most famous and influential fusion reactors.

(Top image: Internal view of the JET tokamak superimposed with an image of plasma flows)

Japan’s JT-60SA Generates First Plasma As World’s Largest Superconducting Tokamak Fusion Reactor

December 6, 2023 by Maya Posch 35 Comments

Japan’s JT-60SA fusion reactor project announced first plasma in October of this year to denote the successful upgrades to what is now the world’s largest operational, superconducting tokamak fusion reactor. First designed in the 1970s as Japan’s Breakeven Plasma Test Facility, the JT-60SA tokamak-based fusion reactor is the latest upgrade to the original JT-60 design, following two earlier upgrades (-A and -U) over its decades-long career. The most recent upgrade matches the Super Advanced meaning of the new name, as the new goal of the project is to investigate advanced components of the global ITER nuclear fusion project.

Originally the JT-60SA upgrade with superconducting coils was supposed to last from 2013 to 2020, with first plasma that same year. During commissioning in 2021, a short circuit in the poloidal field coils caused a lengthy investigation and repair, which was completed earlier this year. Although the JT-60SA is only using hydrogen and later deuterium as its fuel rather than the deuterium-tritium (D-T) mixture of ITER, it nevertheless has a range of research objectives that allow for researchers to study many aspects of the ITER fusion reactor while the latter is still under construction.

Since the JT-60SA also has cooled divertors, it can sustain plasma for up to 100 seconds, to study various field configurations and the effect this has on plasma stability, along with a range of other parameters. Along with UK’s JET, China’s HL-2M and a range of other tokamaks at other facilities around the world, this should provide future ITER operators with significant know-how and experience long before that tokamak will generate its first plasma.

Superconducting Tape Leads To A Smaller Tokamak

July 23, 2023 by Jenny List 80 Comments

Attempts to make a viable nuclear fusion reactor have on the whole been the domain of megabucks projects supported by countries or groups of countries, such as the European JET or newer ITER projects. This is not to say that smaller efforts aren’t capable of making their own advances, operations in both the USA and the UK are working on new reactors that use a novel superconducting tape to achieve a much smaller device.

The reactors in the works from both Oxfordshire-based Tokamak Energy and Massachusetts-based Commonwealth Fusion Systems, or CFS, are tokamaks, a Russian acronym describing a toroidal chamber in which a ring of high-temperature plasma is contained within a spiral magnetic field. Reactors such as JET or ITER are also tokamaks, and among the many challenges facing a tokamak designer is the stable creation and maintenance of that field. In this, the new tokamaks have an ace up their sleeve, in the form of a high-temperature superconducting tape from which those super-powerful magnets can be constructed. This makes the magnets easier to make, cheaper to maintain at their required temperature, and smaller than the low-temperature superconductors found in previous designs.

The world of nuclear fusion is a particularly exciting one to follow in these times of climate crisis, with competing approaches from laser-based devices racing with the tokamak projects to produce the research which will eventually lead to safer carbon-free power. If the CFS or Tokamak Energy reactors lead eventually to a fusion power station on the edge of our cities then it may just be some of the most important work we’ve ever reported.