Helion: linear fusion breakthrough?

Helion linear fusion technology

Helion is developing a linear fusion reactor, which has entirely re-thought the technology (like the ‘Tesla of nuclear fusion’). It could have costs of 1-6c/kWh, be deployed at 50-200MWe modular scale and overcome many challenges of tokamaks. Progress so far includes 100MºC and a $2.2bn fund-raise, the largest of any private fusion company to-date. This note sets out its ‘top ten’ features.

Our overview of nuclear fusion is linked above, spelling out the technology’s game-changing potential in the energy transition. However, fourteen challenges still need to be overcome.

Self-defeatingly, many fusion reactor designs aim to deal with technical complexity via adding engineering complexity. You can do this, but it inherently makes the engineering more costly, with mature reactors likely to surpass 15c/kWh in delivered power.

Helion has taken a different approach, to engineering a fusion reactor. Our ‘top ten features’ are set out below. If you read back through the original fusion report, you will see how different this is…

(1) Costs. Helion has said the reactor will be 1,000x smaller and 500x cheaper than a conventional fusion reactor, with eventual costs seen at 1-6c/kWh. This would indeed be a world-changer for zero carbon electricity (chart below).

(2) Linear Reactor. This is not a tokamak, stellarator or inertial confinement machine (see note). It is a simple, linear design, where pulsed magnetic fields accelerate plasma into a burn-chamber at 1M mph. Colliding plasma particles fuse. The fusion causes the plasma to expand. Energy is then captured from the expanding plasma. It is like fuel in a diesel engine.

(3) Direct electricity generation. Most power generators work by producing heat. The heat turns water into high-pressure steam, which then drives a turbine. Within the turbine, electricity is generated by Faraday’s law, as a moving magnetic field induces a current in stator coils of the turbine (see our note below for a primer on power-electronics). However, a linear reactor containing can exploit Faraday’s law directly. Plasma particles are electro-magnetically charged. So as they expand, they will also induce a current. Some online sources have suggested 95% of the energy released from the plasmas could be converted to electricity, versus c40% in a typical turbine.

(4) Reactor size. The average nuclear fission plant today is around 1GW. Very large fusion plants are gearing up to be similar in size. However, Helion’s linear reactor is seen on the order of c50MW. This is something on the magnitude that can be deployed by individual power consumers, or more ambitiously, on mobile applications, such as in commercial shipping vessels or aviation.

(5) Fewer neutrons. Helion’s target fuel is Helium-3. This is interesting because fusing 2 x Helium-3 nuclei yields a Helium-3 nucleus plus two hydrogen nuclei. There are no net neutron emissions and resultant radioactivity issues (see fusion note). However, the Helium-3 would need to be bred from Deuterium, which is apparently one of the goals in the Polaris demonstration reactor (see below).

(6) Beta. Getting a fusion reactor to work energy-efficiently requires maximizing ‘beta’. Beta is the ratio of plasma field energy to confining magnetic field energy. Helion’s patents cover a field reversed configuration of magnets which will “have the highest betas of any plasma confining system”. During compression, different field coils with successively smaller radius are activated in sequence to compress and accelerate the plasmoids “into a radially converging magnetic field”.  Helion is targeting a beta close to 100%, while tokamaks typically achieve closer to 5%.

(7) Capital. In November-2021, Helion raised a $2.2bn Series-E funding round. This is the largest private fusion raise on record (database below). It is structured as a $500M up-front investment, with an additional $1.7bn tied to performance milestones.

(8) Progress so far. In 2021, Helion became the first private fusion company to heat a fusion plasma to 100MºC. It has sustained plasma for 1ms. It has confined them with magnetic fields over 10 Teslas. Its Trenta prototype has run “nearly every day” for 16-months and completed over 10,000 high-power pulses.

(9) Roadmap to commerciality? Helion is aiming to develop a seventh prototype reactor, named Polaris, which will produce a net electricity gain, hopefully by 2024. It has said in the past that fully commercial reactors could be ‘ready’ by around 2029-30.

(10) Technical Risk. We usually look to de-risk technologies by reviewing their patents. This is not possible for Helion, because we can only find a small number of its patents in the usual public patent databases. Developing a commercial fusion reactor still has enormous challenges. What helps is a landscape of different companies exploring different solutions. For a review of how this has helped to de-risk, for example, plastic pyrolysis, see our recent update below: 60% of the companies have face steeper setbacks than hoped, but a handful are now reaching commercial scale-up.

Other exciting next-generation nuclear companies to cross our screen our highlighted in the data-files below…

To read more about our outlook on nuclear flexibility and how we see nuclear growth accelerating, please see our article here.

Nuclear fusion: what are the challenges?

Nuclear fusion could provide a limitless supply of zero-carbon energy from the 2030s onwards. Thus 30 private companies have raised $4bn to progress new ideas. But the goal of this 20-page note is simply to understand the challenges for fusion reactors, especially deuterium-tritium tokamaks. Innovations need to improve EROI, stability, longevity and ultimate costs.


The purpose of this note is to help decision-makers understand nuclear fusion, simply, in plain language, assuming that you are reasonably literate in science and economics, but do not have a pre-existing degree in nuclear physics.

Binding energies of atomic nuclei are a fundamental force shaping our universe. They explain why some atoms release energy as they fission, and some atoms release energy as they fuse. It is easy to quantify ‘how much energy’ using pages 2-3 of the report.

So is nuclear fusion a real and feasible energy source? We outline why it is on page 4. But there are fourteen challenges that a reactor will need to overcome.

Heating up a nuclear fusion fuel is covered on pages 4-7, covering possible fuel selections, the ‘Coulomb barrier’ for achieving fusion, and heating methods that can surpass 100M C temperatures.

Confining a plasma is covered on pages 8-9, explaining how super-conducting magnets can levitate a stream of super-heated, charged particles. Or not.

Ignition of plasma. What happens to the reaction products? How do you harness the heat? Without the reactor melting? Without other safety issues? We answer these questions on pages 10-12.

Practical considerations for running a fusion reactor are: How do you source, purify and inject fuels to the reactor? What energy gain factor is needed? What maintenance requirements and costs? How flexible will the reactor be? Can reactors be down-sized? We answer these questions on pages 13-17.

Economic considerations. Limitless energy does not necessarily mean cheap energy. At the moment, we think fusion could reach commerciality in the 2030s, but it will ‘split the global CO2 abatement cost curve’ into two. Effectively there would be no need for abatement options costing more than $200-300/ton and create an effective ‘cap’ on all future energy prices.

Decarbonizing global energy: the route to net zero?

This 18-page report revises our roadmap for the world to reach ‘net zero’ by 2050. The average cost is still $40/ton of CO2, with an upper bound of $120/ton, but this masks material mix-shifts. New opportunities are largest in efficiency gains, under-supplied commodities, power-electronics, conventional CCUS and nature-based CO2 removals.


This note looks back across 750 of our research publications from 2019-21 and updates our most practical, lowest cost roadmap for the world to reach ‘net zero’. Our framework for decarbonizing 80GTpa of potential emissions in 2050 is outlined on pages 2-3.

Our updated roadmap is presented on pages 4-6. Most striking is the mix-shift. New technologies have been added at the bottom of the cost curve. Other crucial components have re-inflated. And we have also been able to tighten the ‘risking factors’ on earlier-stage technologies, thus an amazing 87% of our roadmap is not technically ready.

The resulting energy mix and costs for the global economy are spelled out on pages 7-8, including changes to our long-term forecasts for oil, gas, renewables and nuclear.

What has changed from our 2020 roadmap? A full attribution is given on pages 9-10. Disappointingly, global emissions will be 2GTpa higher than we had hoped mid-decade, as gas shortages perpetuate the use of coal.

A more detailed review of our roadmap is presented on pages 11-18. We focus on summarizing the key changes in our outlook in 2021, in a simple 1-2 page format: looking across renewables, nuclear, gas shortages, inflationary feedback loops, more efficiency gains, carbon capture and storage and nature-based carbon removals.

Back-stopping renewables: the nuclear option?

Nuclear power can backstop much volatility in renewable-heavy grids, for costs of 15-25c/kWh. This is at least 70% less costly than large batteries or green hydrogen, but could see less wind and solar developed overall. This 13-page note reviews nuclear flexibility and sees nuclear growth accelerating.


Four types of volatility in renewable-heavy grids are described on page 2 and will require a back-up.

There are limitations for batteries in hydrogen, in smoothing this volatility, as discussed on pages 3-4.

What about nuclear? An improving economic rationale is noted on pages 5-6, prompting us to re-visit the possibility of flexible nuclear plant operation.

Technical issues for maneuvering large nuclear power plants, scaling their output up and down, are laid out from first principles on pages 7-11, including minute-by-minute ramp-rates and the largest challenge, which is cold-starts.

The economics of nuclear flexibility are calculated on page 12, showing costs around 15-25c/kWh for a new Western greenfield facility, which is less than large batteries and hydrogen.

Our conclusions – and who benefits – are summarized on page 13.

Nuclear power: what role in the energy transition?

Uranium markets could be 50-75M lbs under-supplied by 2030. This deficit is deeper than other commodities in our roadmap to net zero. Demand is driven by China, constructing reactors for 50-70% less than the West, yielding zero carbon power at 6-8c/kWh. This 18-page note presents the outlook for nuclear in the energy transition and screens uranium miners.


An overview of the nuclear power industry is outlined on pages 2-5, in order to understand the market, its sub-components, and the energy-economics of nuclear power generation.

Capex costs have held back nuclear growth in the West, as heavy investments and devastating delays can kill IRRs and require 16c/kWh levelized costs (pages 6-7).

China is different, constructing new reactors for 50-70% less than the West, yielding passable economics at 6-8c/kwh, while generating clean baseload power (pages 8-9).

China drives our demand forecasts, underpinning 75% of future global demand on our ‘roadmap to net zero’, with stark upside as a diversification to under-supplied LNG markets, if China exports its technology and as new start-ups require inventory builds (pages 10-13).

Impacts on the uranium market are quantified on page 14. We are bridging to 50-75M lbs of under-supply by 2030, with risks skewed to the upside.

Uranium prices must re-inflate, from sub-$30/lb to $60-90/lb marginal costs (page 15).

Uranium miners are screened on pages 16-18, including profiles of ten public companies, from incumbents to early-stage developers. Rare Earth metals are a common by-product of uranium mining and also relevant to the energy transition.

Copyright: Thunder Said Energy, 2022.