General Fusion is a Canadian company based in Vancouver, British Columbia, which is developing a fusion power device based on magnetized target fusion (MTF). The company was founded in 2002 by Dr. Michel Laberge. The company has more than 150 employees in three countries, with additional centers co-located with fusion research laboratories near London, and Oak Ridge, Tennessee, US.
The device under development injects the magnetized target, a plasma mass in the form of a compact toroid, into a cylinder of spinning liquid metal. The target is mechanically compressed to fusion-relevant densities and pressures, by anywhere from a dozen to hundreds (in various designs) of steam-driven pistons.[1][2][3]
In 2018, the firm published papers on a spherical tokamak, instead of a toroid. It is unclear if this represents a major design change.[4] In June 2021, the company announced it would build 70% of a full scale fusion demonstration plant in the UK as part of a public-private partnership with the UK Government.[5]
Organization
General Fusion's CEO is Greg Twinney.
Michel Laberge, Chief Science Officer, holds multiple responsibilities at General Fusion, including building partnerships with international research institutions, and overseeing partnerships with governments and other companies, and technology development strategy.
The board of directors is chaired by Klaas De Boer, who currently chairs AIM-listed Xeros Technology Group and serves on the Boards of SmartKem and vasopharm.
Technology
Diagram of the General Fusion power plant
General Fusion's approach is based on the Linus concept developed by the United States Naval Research Laboratory (NRL) beginning in 1972.[6][7][8] Researchers at NRL suggested an approach that retains many of the advantages of liner compression to achieve small-scale, high-energy-density fusion.[9] According to Laberge, Linus could not properly time the compression using the technology of the era. Faster computers provide the required timing.[10][8] However, this claim is not borne out by the literature as various Linus devices with no timing constraints, including systems using single pistons, were built during the experimental runs during the 1970s and demonstrated fully reversible compression strokes.[11]
General Fusion's magnetized target fusion system uses a ~3 meter sphere filled with a mix of molten liquid lead and lithium. The liquid is spun, creating a vertical cavity in the centre of the sphere. This vortex flow is established and maintained by an external pumping system; liquid flows into the sphere through tangentially directed ports at the equator and exits radially through ports near the poles of the sphere.[12]
Plasma injector
A plasma injector is attached to the top of the sphere, from which a pulse of magnetically confined deuterium-tritiumplasma fuel is injected into the center of the vortex. A few milligrams of gas are used per pulse. The gas is ionized by a bank of capacitors to form a spheromak plasma (self-confined magnetized plasma rings) composed of the deuterium–tritium fuel.[13][14]
The outside of the sphere is covered with steam pistons, which push the liquid metal and collapse the vortex, thereby compressing the plasma. The compression increases the density and temperature of the plasma to the range where the fuel atoms fuse, releasing energy in the form of fast neutrons and alpha particles.[14]
Pistons for plasma compression
This energy heats the liquid metal, which is then pumped through a heat exchanger to generate electricity via a steam turbine. The plasma forming and compressing process repeats and the liquid metal is continuously pumped through the system. Some of the steam is recycled to power the pistons.[15][12]
In addition to its role in compressing the plasma, the liquid metal liner shields the power plant structure from neutrons released by the deuterium-tritium fusion reaction, overcoming the problem of structural damage to plasma-facing materials.[16][12] The lithium in the mixture breeds tritium.[12][17]
Fusion Demonstration Program
The Fusion Demonstration Program is a 70% scale prototype which was being built in Oxfordshire, UK with a reported cost of US$400 million.[18] It had been announced that the core technology had been proven out and was ready to be put together[19] and that the plant was to commence operations in 2027.[20] However the plant was put on hold in 2023 when the company announced that it would instead build a different machine in Canada aimed at demonstrating breakeven by 2026.[21]
The plant had several key differences from the commercial power plant concept:
1 pulse per day repetition rate[20] vs 1 pulse per second for a power plant.
Among other things this increases the time available to re-establish the high vacuum conditions required for plasma formation by a factor of 86400, avoiding a significant engineering obstacle that will need to be solved for any future commercial application to be viable.
Drive gas system using helium rather than hydraulic rams.[22]
A compression system using liquid lithium rather than lead-lithium.[22]
Ideally plasma facing materials should be composed of light elements. Plasma contamination by heavier elements, such as lead, significantly increase plasma power loss due to Bremsstrahlung radiation.[23] The choice of lithium rather than lead-lithium therefore significantly reduces plasma power losses making the demonstration program much more viable than it otherwise would be. However, this comes at the expense of having to solve materials compatibility issues[24] with lithium rather than lead-lithium as will be necessary for any future power plant.
History
General Fusion predict that fusion power is just 10 years away
In 2005 it produced a fusion reaction in its first MTF prototype.[citation needed] In 2010, it produced its first at-scale plasma injector with magnetically confined plasma. In 2011 it first demonstrated compressive heating of magnetized plasma.[citation needed]
A proof-of-concept compression system was constructed in 2013 with 14 full size pistons arranged around a 1-meter diameter spherical compression chamber to demonstrate pneumatic compression and collapse of a liquid metal vortex.[26][27] The pneumatic pistons were used to create a converging spherical wave to compress the liquid metal. The 100kg, 30cm diameter hammer pistons were driven down a 1 m long bore by compressed air.[27][14] The hammer piston struck an anvil at the end of the bore, generating a large amplitude acoustic pulse that was transmitted to the liquid metal in the compression chamber.[27] To create a spherical wave, the timing of these strikes had to be controlled to within 10 µs. The firm recorded sequences of consecutive shots with impact velocities of 50m/s and timing synchronized within 2 µs.[27] However it was found that the wall of the liquid metal vortex turned to a spray soon after the arrival of the pressure wave.[27]
From its inception until 2016, the firm built more than a dozen plasma injectors.[28] These include large two-stage injectors with formation and magnetic acceleration sections (dubbed "PI" experiments), and three generations of smaller, single-stage formation-only injectors (MRT, PROSPECTOR and SPECTOR).[29] The firm published research demonstrating SPECTOR lifespans of up to 2 milliseconds and temperatures in excess of 400 eV.[29]
As of 2016, the firm had developed the power plant's subsystems, including plasma injectors and compression driver technology.[30] Patents were awarded in 2006 for a fusion energy reactor design,[31] and enabling technologies such as plasma accelerators (2015),[32] methods for creating liquid metal vortexes (2016)[33] and lithium evaporators (2016).[34]
In 2016 the GF design used compact toroid plasmas formed by a coaxial Marshal gun (a type of plasma railgun), with magnetic fields supported by internal plasma currents and eddy currents in the flux conserver wall.[35] In 2016, the firm reported plasma lifetimes up to 2 milliseconds and electron temperatures in excess of 400 eV (4,800,000°C).[29]
Around 2017 the company performed a series of experiments referred to as PCS (Plasma Compression Small). These implosion experiments used a chemical driver (a euphemism for an explosive) to compress an aluminum liner onto a compact toroid plasma. This is a very similar process to that used in implosion type nuclear weapons such as The Gadget. Because the implosions involved chemical explosives, the tests took place outdoors in remote locations. The tests were destructive and could only be executed every few months. These tests were carried out to advance the understanding of plasma compression with the goal of advancing toward a nuclear-reactor scale demonstration.[36][37][38]
As of December2017[update], the PI3 plasma injector held the title as the world's most powerful plasma injector, ten times more powerful than its predecessor.[39] It also achieved stable compression of plasma.[citation needed]
In 2019 it successfully confined plasma within its liquid metal cavity.[citation needed] From 2019 to 2021 it increased plasma performance.
As of 2021, the firm had approximately 140 employees[40] and had raised over C$150 million in funding from a global syndicate of investors.[41][42] It demonstrated compression of a water cavity into a controlled, symmetrical shape.[43]
Also in 2021 the company agreed to build a demonstration plant in Oxfordshire, at Culham, the center of the UK's nuclear R&D. The plant is planned to be 70% of the size of a commercial power plant. The company claimed it had validated all the individual components for the demonstration reactor.[44]
In 2022, the company announced that it had completed 200,000+ plasma shots, filed 150 patents/patents pending, and that headcount had passed 200. PI3 reached 10 ms confinement times and temperatures of 250 eV, almost 3 million degrees Celsius, without active magnetic stabilization, auxiliary heating, or a conventional divertor. Its primary compression testbed, a 1:10 scale system using water rather than liquid metal,[45] has completed over 1,000 shots, behaving as predicted.[43]
In 2023, the firm reduced headcount significantly and announced that it was building a new machine, “LM26”, with the goal of achieving breakeven by 2026. The Fusion Demonstration Plant being built in the UK will be delayed.[21]
Criticisms
Magnetized target fusion has a number of challenges. General Fusion's founder and Chief Science Officer noted several specific difficulties that are not present in DC tokamaks. These include, but are not limited to:
Confinement at high energy density is not known.
Liquid metal vaporization.
Impurities from the liquid metal cooling the plasma.
Forming an initial spherical liquid surface.
Kink instability of the liquid metal shaft.
Symmetry of implosion.
Flux diffusion in the liquid metal.
Laberge stated that these challenges were still to be solved.[4] Indeed, General Fusion are yet to demonstrate mechanical compression of a plasma by a liquid metal wall,[46] despite this being a key technology required for their powerplant. Nor have they demonstrated a liquid metal shaft, or a means of re-establishing high vacuum conditions in the short time interval (<1 s) between pulses.
The MTF powerplant proposed by General Fusion would produce just 40 MW of electricity.[4] This is equivalent to the output of 3x13MW wind turbines, or around 10% of a conventional combined cycle gas turbine unit. Moreover, this specification was based on optimistic assumptions that the plasma would be compressed adiabatically, and that no energy is required for tritium separation. As a result, in practice net electricity to the grid would be expected to be lower than predicted.
The proposed reactor uses a lead-lithium liner to contain the fusion reaction.[27] Harmful radioactive substances will be produced as a result of neutron activation of the lead-lithium material. Polonium-210 (210Po) and mercury-203 (203Hg) are of special concern.[47]210Po is extremely toxic and 203Hg is highly mobile due to its high vapor pressure. These dangerous substances will complicate maintenance, will require contingency plans for accidental release, and will need a strategy for decommissioning the facility and storing the radioactive waste.
Research collaborations
Microsoft: In May 2017 General Fusion and Microsoft announced a collaboration to develop a data science platform based on Microsoft's Azure cloud computing system. A second phase of the project was to apply machine learning to the data, with the goal of discovering insights into the behavior of high temperature plasmas. The new computational program would enable General Fusion to mine over 100 terabytes of data from the records of over 150,000 experiments. It was to use this data to optimize the designs of their fusion system's plasma injector, piston array, and fuel chamber. During this collaboration, the Microsoft Develop Experience Team was to contribute their experience and resources in machine learning, data management, and cloud computing.[48]
Los Alamos National Laboratory: General Fusion entered a cooperative research and development agreement (CRADA) with the U.S. Department of Energy's Los Alamos National Laboratory for magnetized target fusion research.[49]
McGill University: In 2017 McGill University and General Fusion acquired an Engage Grant from the Natural Sciences and Engineering Research Council of Canada to study General Fusion's technology. Specifically, the project was to use McGill's diagnostic abilities to develop techniques to understand the behavior of the liquid metal wall during plasma compression and how it might affect the plasma.[50]
Queen Mary University of London: In 2015 General Fusion funded a research study on high fidelity simulations of non-linear sound propagation in multiphase media of nuclear fusion reactor pursued using QMUL CLithium and Y codes.[52]
Hatch Ltd: General Fusion and Hatch Ltd. joined in 2015 to create a fusion energy demonstration system. The project aimed to construct and demonstrate, at power plant scale, the primary subsystems and physics underpinning General Fusion's technology, including their proprietary Magnetized Target Fusion (MTF) technology. Simulation models will be used to verify that this fusion energy system is commercially and technically viable at scale.[30]
Culham Centre for Fusion Energy: In June 2021, General Fusion announced it would accept the UK government's offer to host the world's first substantial public-private partnership fusion demonstration plant, at Culham. The plant will be constructed from 2022 to 2025 and is intended to lead the way for commercial pilot plants in the late 2020s or early 2030s. The plant will be 70% of full scale and is expected to attain a stable plasma of 150 million degrees using deuterium fuel.[53][54] In October 2022 the UKAEA and General Fusion elaborated on the nature of their partnership, stating that it will "harness UKAEA’s extensive neutron modelling software and expertise to simulate the neutron flux distribution from General Fusion’s operational large-scale plasma injector", including by building a new, larger Thomson scattering system for General Fusion's demonstration machine.[55]
Funding
As of 2021, General Fusion had received $430 million in funding.[54][56] General Fusion was not among the eight companies to receive funding as part of the United States Department of Energy Milestone-Based Fusion Development Program.[57]
Chrysalix Energy Venture Capital, a Vancouver-based venture capital firm, led a C$1.2 million seed round of financing in 2007.[2][59][60] Other Canadian venture capital firms that participated in the seed round were GrowthWorks Capital and BDC Venture Capital.
In 2009, a consortium led by General Fusion was awarded C$13.9 million by SDTC to conduct a four-year research project on "Acoustically Driven Magnetized Target Fusion";[61] SDTC is a foundation established by the Canadian government.[62] The other member of the consortium is Los Alamos National Laboratory.[61]
A 2011 Series B round raised $19.5 million from a syndicate including Bezos Expeditions, Braemar Energy Ventures, Business Development Bank of Canada, Cenovus Energy, Chrysalix Venture Capital, Entrepreneurs Fund, and Pender Ventures.[63][64]
In May 2015 the government of Malaysia's sovereign wealth fund, Khazanah Nasional Berhad, led a $27 million funding round.[65]
SDTC awarded General Fusion a further C$12.75 million in March 2016 to for the project "Demonstration of fusion energy technology" in a consortium with McGill University (Shock Wave Physics Group) and Hatch Ltd.[30]
In October 2018 Canadian Minister for Innovation, Science and Economic Development, Navdeep Bains, announced that the Canadian government's Strategic Innovation Fund would invest C$49.3 million in General Fusion.[42]
In December 2019, General Fusion raised $65 million in Series E equity financing from Singapore's Temasek Holdings, Bezos and Chrisalix, concurrently with another $38 million from Canada's Strategic Innovation Fund. The firm said the funds would permit it to begin the design, construction, and operation of its Fusion Demonstration Plant.[66][67]
In January 2021, the company announced funding by Shopify founder Tobias Lütke's Thistledown Capital.[68]
In November 2021, the company completed an over-subscribed $130M Series E round. Investors included Bezos, Business Development Bank of Canada, hedge fund Segra Capital Management and family-office investors. Funds were to be dedicated to constructing a commercial reactor.[56]
The first challenge was Method for Sealing Anvil Under Repetitive Impacts Against Molten Metal.[69] General Fusion successfully sourced a solution for "robust seal technology" capable of withstanding extreme temperatures and repetitive hammering, so as to isolate the rams from the liquid metal that fills the sphere. The firm awarded Kirby Meacham, an MIT-trained mechanical engineer from Cleveland, Ohio, the $20,000 prize.[70]
A second challenge, Data-Driven Prediction of Plasma Performance, began in December 2015 with the aim of identifying patterns in the firm's experimental data that would allow it to further improve the performance of its plasma.[71]
The third challenge ran in March 2016, seeking a method to induce a substantial current to jump a 5–10cm gap within a few hundred microseconds, and was titled "Fast Current Switch in Plasma Device".[72] A prize of $5,000 was awarded to a post-doctoral researcher at Notre Dame.[73]
A fusion rocket is a theoretical design for a rocket driven by fusion propulsion that could provide efficient and sustained acceleration in space without the need to carry a large fuel supply. The design requires fusion power technology beyond current capabilities, and much larger and more complex rockets.
Inertial confinement fusion (ICF) is a fusion energy process that initiates nuclear fusion reactions by compressing and heating targets filled with fuel. The targets are small pellets, typically containing deuterium (2H) and tritium (3H).
Fusion power is a proposed form of power generation that would generate electricity by using heat from nuclear fusion reactions. In a fusion process, two lighter atomic nuclei combine to form a heavier nucleus, while releasing energy. Devices designed to harness this energy are known as fusion reactors. Research into fusion reactors began in the 1940s, but as of 2024, no device has reached net power, although net positive reactions have been achieved.
Nuclear pulse propulsion or external pulsed plasma propulsion is a hypothetical method of spacecraft propulsion that uses nuclear explosions for thrust. It originated as Project Orion with support from DARPA, after a suggestion by Stanislaw Ulam in 1947. Newer designs using inertial confinement fusion have been the baseline for most later designs, including Project Daedalus and Project Longshot.
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Magnetic confinement fusion (MCF) is an approach to generate thermonuclear fusion power that uses magnetic fields to confine fusion fuel in the form of a plasma. Magnetic confinement is one of two major branches of controlled fusion research, along with inertial confinement fusion.
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Inertial Fusion Energy is a proposed approach to building a nuclear fusion power plant based on performing inertial confinement fusion at industrial scale. This approach to fusion power is still in a research phase. ICF first developed shortly after the development of the laser in 1960, but was a classified US research program during its earliest years. In 1972, John Nuckolls wrote a paper predicting that compressing a target could create conditions where fusion reactions are chained together, a process known as fusion ignition or a burning plasma. On August 8, 2021, the NIF at Livermore National Laboratory became the first ICF facility in the world to demonstrate this. This breakthrough drove the US Department of Energy to create an Inertial Fusion Energy program in 2022 with a budget of 3 million dollars in its first year.
Magnetized Target Fusion (MTF) is a fusion power concept that combines features of magnetic confinement fusion (MCF) and inertial confinement fusion (ICF). Like the magnetic approach, the fusion fuel is confined at lower density by magnetic fields while it is heated into a plasma. As with the inertial approach, fusion is initiated by rapidly squeezing the target to greatly increase fuel density and temperature. Although the resulting density is far lower than in ICF, it is thought that the combination of longer confinement times and better heat retention will let MTF operate, yet be easier to build. The term magneto-inertial fusion (MIF) is similar, but encompasses a wider variety of arrangements. The two terms are often applied interchangeably to experiments.
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Michel Laberge is a Canadian physicist and entrepreneur. He is the founder and CSO of General Fusion, and was previously a senior physicist and principal engineer at Creo Products for nine years.
The Linus program was an experimental fusion power project developed by the United States Naval Research Laboratory (NRL) starting in 1971. The goal of the project was to produce a controlled fusion reaction by compressing plasma inside a metal liner. The basic concept is today known as magnetized target fusion.
The history of nuclear fusion began early in the 20th century as an inquiry into how stars powered themselves and expanded to incorporate a broad inquiry into the nature of matter and energy, as potential applications expanded to include warfare, energy production and rocket propulsion.
↑ Robson, A. E. (1980). "A Conceptual Design for an Imploding-Liner Fusion Reactor". Megagauss Physics and Technology. Springer US. pp.425–436. ISBN978-1-4684-1050-1.
1 2 The global fusion industry in 2023 - Fusion Companies Survey by the Fusion Industry Association(PDF) (Report). Fusion Industry Association. 12 July 2023. p.41. Retrieved 13 July 2023. LM26 is designed to achieve fusion conditions of over 100 million degrees Celsius by 2025, with a goal of achieving breakeven by 2026. The data gathered from LM26 will be incorporated into the design of the company's planned near-commercial machine in the UK.
↑ Russ Ivanov, Patrick Carle, Neil Carter, Ken Jensen, Stephen Howard, Michel Laberge, Alex Mossman, Peter O’Shea, Adrian Wong, William Young "SPECTOR 1 Plasma as a Target for Adiabatic CompressionArchived 15 December 2016 at the Wayback Machine " Poster presented at the 58th Annual Meeting of the APS Division of Plasma Physics 31 October – 4 November 2016. San Jose, California. CP10.00106
↑ "PCS". Fusion Energy Base. Archived from the original on 5 February 2023. Retrieved 5 February 2023.
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