In SyFy's/ Amazon's science fiction series The Expanse, the main cast's spaceship (Rocinante) uses a modified Epstein drive, a fictional technology whose main energy source is based on laser-ignited nuclear fusion. Some nuclear fusion startups aim to miniaturize fusion reactors for applications in space.
There is this old joke about nuclear fusion always being 30 years away. But now it looks like things are speeding up. Scientists have adjusted their expectations based on current advances in technology reducing the estimated timeline for a fusion breakthrough to about 18 years into the future. Several young companies want to be even faster – they are part of a fast-growing market.
<span class="firstcharacter">S</span>ince the 1920s nuclear fusion has slowly gained momentum with progress accelerating after the 1950s. Next to successful large-scale thermonuclear fusion bomb experiments, early experimental reactors like ZETA in the UK were created as proof of concept, generating valuable data and insights (even though this particular one didn't deliver).
The reactor achieved a breakthrough by maintaining a plasma temperature exceeding 100 million degrees Celsius for 1,066 seconds
As of July 2024, according to the annual report by the Fusion Industry Association (FIA), the fusion industry has now attracted over $7.1bn of investment distributed among 45 different companies.[1]
To find out about positive side or extra applications of nuclear fusion scroll to the end of the article.
Short Overview: Nuclear Fusion
The concept of nuclear fusion began to take shape in the 1920s in England. It is the process by which two light atomic nuclei, such as isotopes of hydrogen (like deuterium and tritium) combine under extreme pressure to form a heavier nucleus like helium. The process releases neutrons which carry high amounts energy. When the neutrons hit the blanket material (e.g. made of a lithium compound) surrounding the reactor, the material heats up. The heat can then be used to generate electricity.
This reaction powers stars, including our Sun, and has the potential to provide a nearly limitless and clean energy source on Earth. In stars these fusion events occur naturally under immense gravitational pressure. On Earth, achieving the necessary conditions for fusion requires advanced technology to replicate these extreme environments.
To make this possible the involved particles have to achieve extreme temperatures to overcome the Coulomb barrier, the repulsive force between the positively charged nuclei, allowing them to come close enough for the strong nuclear force to take over and fuse. For deuterium-tritium fusion the required temperature is around 100.000.000 (100 million) degrees Celsius and 5-6,600,000,000 (5-6,6 billion) degrees Celsius for the deuterium-boron-11 (p-B11) Fusion.
Researchers are exploring several methods to achieve controlled nuclear fusion – the most developed and adopted are:
Magnetic Confinement Fusion (MCF): This approach uses strong magnetic fields to confine hot plasma, preventing it from touching reactor walls. The most prominent technologies are Tokamak and Stellarator reactors which feature different magnet-based confinement methods.
Inertial Confinement Fusion (ICF): This method involves compressing a small pellet of fusion fuel using powerful lasers or particle beams to achieve the necessary conditions for fusion. olves compressing a small pellet of fusion fuel using powerful lasers or particle beams to achieve the necessary conditions for fusion.
Other methods often combine or expand on the features and processes used in MCF or ICF:
A combination of MCF and ICF: Magnetized Target Fusion (MTF)
Variants or extensions of MCF: Field Reversed Configuration (FRC) and Z-Pinch Fusion
Variants of ICF: Intertial Electrostratic Confinement (IEC) and Laser-Induced Fusion
A variant of MCF and IEC: Polywell Fusion
Challenges
Achieving net positive energy: Fusion reactors still struggle to generate more energy than they consume, a critical step for making fusion a viable energy source.
Plasma containment and stability: Maintaining stable confinement of the high-temperature plasma without it touching the reactor walls remains a significant challenge, particularly with the extreme conditions involved.
Material degradation: Fusion reactions cause neutron-induced damage, thermal cycling, and corrosion of reactor materials, leading to degradation over time and the need for advanced, durable materials.
Tritium Supply and material breeding: The need for tritium as one of the fusion fuels presents logistical issues, as it must be bred within the reactor itself due to its scarcity.
1. Marvel Fusion (Germany, founded 2019)
Method: The approach is a new direction in the field of Inertial Confinement Fusion (ICF). The company plans to use ultrashort-pulse 100 joule lasers (on the order of femtoseconds, so one quadrillionth of a second[2, 3]), which are much shorter than the long-pulsed 20-nanosecond laser pulses used by the other facilities. The company is building the $150 million »ATLAS« research facility in partnership with Colorado State University in the US. The lasers are supposed to fire with a 100-femtosecond pulse duration at 10 times per second (10 Hz).[4]
The company focuses on using nanostructured silicon targets in combination with the Proton-Boron-11 (p-B11) fusion reaction, which is aneutronic, thus producing minimal neutron radiation[5]. When the laser strikes the silicon, it ionizes the material, releasing electrons and leaving behind positively charged silicon nuclei. These silicon ions are then accelerated by the laser's energy, creating a highly energetic plasma. The accelerated ions collide with the surrounding p-B11 fuel layers, compressing and heating the fuel to extreme temperatures, thereby initiating the fusion reaction. In this process, the fusion of protons with boron-11 produces alpha particles (helium nuclei) instead of harmful neutrons, making the process aneutronic and significantly reducing radioactive byproducts.
<span style="color: #008091;">Aneutronic fusion:</span> The p-B11 fusion process produces alpha particles instead of neutrons, minimizing radiation hazards, making it safer and easier to maintain.
<span style="color: #008091;">Silicon targets:</span> Nanostructured silicon increases laser absorption, optimizing energy transfer to the fuel.
<span style="color: #008091;">Abundant fuel:</span> Boron is non-radioactive, abundant, and more sustainable than tritium.[6]
<span style="color: #008091;">Lower temperature needs:</span> Quantum effects are supposed to help avoid the typical thermonuclear route which involves heating up plasma to over 5 billion degrees Celsius to create a p-B11 fusion.[5]
<span style="color: #008091;">Laser precision:</span> Achieving consistent and accurate energy delivery remains a technical challenge.
<span style="color: #008091;">Target material:</span> While silicon is an easy material to produce, manufacturing precise nanostructured targets is technically demanding and costly.
<span style="color: #008091;">Mixed fuels:</span> The use of mixed fuels leads to increased energy losses and may complicate the need for precompression, making it harder to achieve efficient fusion conditions.[7]
<span style="color: #008091;">Energy delivery:</span> Although the energy per pulse is much lower than in other approaches (100 joule), the peak power needed to deliver this energy in ultra-short bursts is much higher (multi-petawatts).
Company’s projected <strong>commercial viability:</strong> the 2030s
2. OpenStar (New Zealand, founded 2021)
Method:The company is pioneering a levitated dipole fusion reactor design, inspired by the Levitated Dipole Experiment (LDX) at MIT[8]. The reactor, with its doughnut-shaped configuration, uses a superconducting magnet which levitates at its core to help achieve magnetic confinement for the plasma. This process puts the method into the same category as other MCF approaches featuring similarities to the tokamak design but reverses the magnetic setup.
Recently, OpenStar achieved plasma temperatures of 300,000°C[9], a key milestone, but since it uses deuterium and tritium (D-T) as fuel it is still far below the 100 million degrees Celsius required for efficient fusion. By floating the superconducting magnet within the plasma, OpenStar improves plasma stability and energy confinement more efficiently than traditional methods.
<span style="color: #008091;">Levitated dipole design:</span> The use of levitated superconducting magnets improves plasma stability and allows for simpler and more scalable reactors compared to traditional tokamaks.[10]
<span style="color: #008091;">Cost-effective scalability:</span> The simplified design aims to reduce construction and operational costs, improving scalability for commercial fusion.
<span style="color: #008091;">Plasma stabilization:</span> Achieving long-term containment, reaching the required 100 million degrees Celsius for fusion, and maintaining control at higher temperatures remains a key challenge.
<span style="color: #008091;">Superconducting magnet limitations:</span> The superconducting magnets must be kept at extremely low temperatures, requiring advanced cooling systems.
Company’s projected <strong>commercial viability:</strong> the 2030s
3. First Light Fusion (UK, founded 2011)
Method: First Light Fusion is pioneering a novel approach to nuclear fusion known as projectile-driven fusion.[11] While their method uses elements of inertial compression it is not classified as either MCF or ICF.
It involves accelerating a metal projectile—typically an aluminium disc—to hypersonic speeds and directing it into a fusion target.[12] The target comprises a fuel capsule containing deuterium and is embedded within a cube, which functions like an amplifier. The cube is designed to focus and amplify the shockwaves generated by the projectile's impact, thereby compressing the fuel capsule to the extreme pressures and temperatures necessary for fusion.[13]
In 2024, the company reached another milestone by setting a record of 1.85 terapascals of pressure while also increasing their standoff distance (projectile travel distance to the fusion target) from 1 cm to 10 cm. They used the »Z Machine« at Sandia National Laboratories to provide additional compression through its precisely timed shockwaves during the projectile’s impact.
The Machine can produce up to 80 TW (trillion watts) of power during a pulse.[14] The current »Machine 3« will be replaced by »Machine 4« which is already under construction. It is supposed to launch in 2027 with the capability of launching projectiles at 60 kms per second and amplified projectile speed of about 200kms per second.[15]
<span style="color: #008091;">Direct compression and simpler setup:</span> Compresses the fusion target using a high-speed projectile, simplifying the setup compared to complex magnetic or laser systems, potentially reducing costs.
<span style="color: #008091;">Lower temperature requirements:</span> Achieves fusion through mechanical compression without the need for a sustained superheated plasma.
<span style="color: #008091;">Standoff distance:</span> Requires a much larger separation between the projectile launcher and fusion target (several meters), complicating setup and requiring precise control.[16]
<span style="color: #008091;">Projectile velocity control and target alignment:</span> Achieving the required high speeds for the projectile and accurate positioning of the fusion target while maintaining precision is a technical challenge.
<span style="color: #008091;">Energy transfer efficiency:</span> Ensuring efficient energy transfer from the projectile to the fusion fuel is critical but may pose a problem.
Company’s projected <strong>commercial viability:</strong> the 2030s
4. Avalanche Energy (USA, founded 2018)
Method:The company is developing a unique approach using electrostatic confinement combined with magnetic confinement of electrons instead of an MCF or ICF approach.[17] Their small design is called Orbitron[18] – the reactor’s plasma core has a diameter of only tens of centimeters. The system uses a cathode energized with a high negative voltage, which strips the deuterium and tritium atoms of their electrons, thereby ionizing the fuel. These ions are then accelerated and shot into the Orbitron’s plasma core, where they start orbiting around the cathode, gaining kinetic energy to overcome the Coulomb barrier and initiate fusion.
At the same time within the core, the electrons are confined alongside the ions by the magnetic field, allowing the ions to be compressed into a high-density plasma while addressing the space charge limit (too many positively charged ions alone would create strong repulsive force preventing plasma density). This process is supposed to enable sustained fusion conditions.
The fusion products then interact with the chamber’s walls, generating heat, which is captured and converted into electricity via a turbine. The company wants to eventually develop a system capable of direct energy conversion, providing a more efficient way to generate power. The reactor operates at voltages up to 300 kilovolts and the system aims to achieve fusion power outputs of kilowatts. The commercial product is intended for dual use.[19]
<span style="color: #008091;">Compact design:</span> The Orbitron’s small size opens up new application opportunities, especially for mobile solutions, potentially in space.[20]
<span style="color: #008091;">Lower operational complexity:</span> The combination of electrostatic and magnetic fields the system avoids the need for complex, high-cost magnetic systems or lasers.
<span style="color: #008091;">Plasma stability:</span> Maintaining long-term plasma stability at high ion densities is challenging, particularly in compact systems.
<span style="color: #008091;">Energy efficiency:</span> Ensuring efficient acceleration and confinement of the ions and electrons minimizing energy losses from bremsstrahlung radiation and cyclotron radiation remains a critical task.
<span style="color: #008091;">Voltage requirements:</span> Even though the company recently achieved 300 kilovolts[21], maintaining this voltage to accelerate the ions requires highly stable and powerful voltage sources, posing engineering challenges.
<span style="color: #008091;">Space charge limit:</span> While the magnetic confinement of electrons mitigates this, there is still a risk of overcoming the space charge limit if ion density gets too high, potentially destabilizing the plasma.
Company’s projected <strong>commercial viability:</strong> not specified – supposed orbital demonstration in 2028.
General observation: A mixed record
Quite a few fusion companies have fancy websites naming lots of buzzwords like »quantum effects« while showing great animations. At the same time there is a lack of technical details or even adequately comprehensive information as to how they want to achieve nuclear fusion or why exactly their approach is feasible.
Often, the overarching vision is roughly the same, focusing on a future that involves an abundance of clean energy. While undoubtedly, their methods involve high-class engineering and novel scientific approaches – the problem is the bold marketing claims which often focus on very steep timeline projections for commercial viability. Those investment-focused narratives often disregard the needed awareness of consuming less energy in order to keep our planet habitable since a new and cheap energy source might cause the exact opposite.
When considering the above-mentioned specific challenges that still need to be solved, I remain highly doubtful that we will see nuclear fusion within the next ten years, especially when it comes to compact ›pocket reactors‹. That being said, I would love to be surprised and see nuclear fusion become reality within my lifetime.
Less known benefits from nuclear fusion
Some of the information I found out about during this research included positive side effects or extra applications of such working fusion reactors – mainly making use of the produced high-energy neutrons:
<span style="color: #008091;">Medical isotope production</span> which involves harnessing fusion reactions to efficiently generate critical isotopes, like molybdenum-99, needed for diagnostic imaging in nuclear medicine. This would offer a more reliable and cost-effective alternative to traditional methods.[22, 23]
<span style="color: #008091;">Neutron Capture Therapy (NCT)</span> would use a mini-fusion reactor or neutron generator to produce high-energy neutrons, delivering targeted radiation to cancer tissue after the tumour absorbs boron-containing compounds.[24]
<span style="color: #008091;">Hydrogen production</span> for fuel cells using fusion would involve using the generated high-energy neutrons to efficiently split water molecules into hydrogen and oxygen, providing a sustainable source of hydrogen fuel.[25]
Due to their higher energy, fusion neutrons could be used in <span style="color: #008091;">advanced materials testing</span> to generate more accurate data from simulations for extreme conditions like space.[26, 27]
Fusion neutrons could improve <span style="color: #008091;">industrial radiographic inspection</span> by providing enhanced resolution and sensitivity for materials that are difficult to assess with conventional X-rays.[28]
<span class="headingcolor" style="display: block; text-align: center;">Thanks for your attention!</span>
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