Beyond Tokamaks: A New Era of Fusion Reactor Design
The quest for clean, sustainable energy has led scientists on a relentless pursuit of one of the most challenging feats of engineering: harnessing the power of nuclear fusion, the very process that fuels the stars. This quest has long centered on the tokamak, a donut-shaped reactor that confines superheated plasma within powerful magnetic fields. While tokamaks have yielded valuable insights and incremental progress, inherent limitations in their design have spurred the exploration of a new wave of innovative reactor designs.
These next-generation concepts promise potentially game-changing advancements in our pursuit of fusion energy, offering tantalizing glimpses of a future powered by a virtually limitless and environmentally friendly energy source. One of the most promising alternatives to the tokamak is the stellarator. Unlike the symmetrical tokamak, stellarators employ complex, twisted magnetic fields generated by external coils, offering the potential for greater plasma stability, a critical factor for sustained fusion reactions. Experiments like the Wendelstein 7-X in Germany are at the forefront of stellarator research, pushing the boundaries of plasma confinement and exploring the intricacies of this intricate design.
Another compelling approach is Inertial Confinement Fusion (ICF), which uses high-powered lasers or ion beams to implode tiny pellets of fuel. This rapid compression creates extreme temperatures and pressures, mimicking the conditions found in the core of stars and igniting a burst of fusion energy. The National Ignition Facility (NIF) in the United States has achieved significant milestones in ICF research, demonstrating the potential of this approach to achieve ignition. Magnetized Target Fusion (MTF) offers a hybrid approach, combining elements of both magnetic and inertial confinement.
By compressing a magnetized plasma target, MTF aims to achieve fusion conditions with lower driver energies than ICF, potentially paving a more efficient path to fusion power. General Fusion, a Canadian company, is pioneering this approach with its innovative compression technology. These diverse approaches underscore the dynamic nature of fusion research, driven by continuous innovation in plasma physics, materials science, and advanced engineering. The ultimate goal remains the same: achieving net energy gain, where the energy produced by the fusion reaction exceeds the energy required to initiate and sustain it. Reaching this critical milestone will unlock the transformative potential of fusion energy, offering a clean, safe, and virtually inexhaustible power source for generations to come.
Stellarators: Twisting Towards Stability
Tokamaks, with their donut-shaped magnetic confinement systems, have been the workhorses of nuclear fusion research for decades. Their relative simplicity in design and ease of construction made them the primary focus in the early years of fusion energy exploration. However, inherent limitations, particularly the reliance on induced plasma current for confinement, have spurred the exploration of alternative reactor designs. These limitations include the risk of plasma disruptions, which can damage the reactor, and the need for continuous current drive, which consumes energy and reduces the overall efficiency of the system.
Stellarators, for example, offer a fundamentally different approach, promising more stable plasma confinement through complex, three-dimensional, twisted magnetic fields generated entirely by external coils. This key difference addresses some of the most pressing challenges facing tokamak-based fusion reactors. The primary advantage of stellarators lies in their ability to sustain stable plasmas without the need for a net toroidal current. This intrinsic stability is achieved through the carefully shaped magnetic fields, meticulously designed to confine the plasma and minimize energy losses.
Unlike tokamaks, which are susceptible to disruptions caused by instabilities in the plasma current, stellarators are designed to be inherently disruption-free. This makes them a potentially more reliable and robust path toward achieving sustained nuclear fusion reactions. The Wendelstein 7-X (W7-X) in Germany, a leading stellarator experiment, has demonstrated impressive results in terms of plasma confinement and stability, validating the theoretical predictions and paving the way for future stellarator designs. The complex geometry of stellarator coils presents a significant engineering challenge.
Fabricating these precisely shaped coils requires advanced manufacturing techniques and materials. The computational design of stellarator magnetic fields is also incredibly demanding, requiring sophisticated algorithms and high-performance computing resources. However, recent advances in both computational modeling and advanced manufacturing, such as 3D printing and precision machining, are making the construction of stellarators more feasible. These technological innovations are crucial for realizing the full potential of stellarator reactor design and overcoming the historical challenges associated with their complex geometries.
While stellarators offer inherent stability advantages, they also face challenges in terms of optimizing plasma performance. The complex magnetic field geometry can lead to increased particle and energy losses compared to idealized tokamak scenarios. Researchers are actively working on optimizing the design of stellarators to minimize these losses and improve overall confinement. This involves careful shaping of the magnetic field to reduce turbulent transport and enhance plasma density and temperature. Furthermore, innovative heating and current drive techniques are being explored to further optimize plasma performance in stellarator reactors.
Looking ahead, the development of advanced materials that can withstand the extreme heat and neutron flux generated by nuclear fusion reactions is crucial for both tokamaks and stellarators. Materials science plays a vital role in ensuring the long-term viability and economic feasibility of fusion power plants. Continued research and innovation in materials science, coupled with advancements in plasma physics and reactor design, will be essential for realizing the promise of clean, sustainable energy from nuclear fusion. The ongoing progress in stellarator research, alongside advancements in inertial confinement fusion and magnetized target fusion, underscores the growing momentum in the global quest for fusion energy and net energy gain.
Inertial Confinement Fusion: A Burst of Energy
Inertial confinement fusion (ICF) represents a radical departure from magnetic confinement strategies like those employed in tokamaks and stellarators. Instead of using magnetic fields to contain a hot plasma, ICF leverages powerful lasers or ion beams to rapidly compress and heat tiny fuel pellets, typically containing deuterium and tritium. This implosion creates extreme temperatures and pressures, hundreds of millions of degrees Celsius and billions of atmospheres respectively, mimicking the conditions found at the core of stars and initiating nuclear fusion.
The fundamental principle is to compress the fuel so rapidly and densely that fusion reactions occur before the fuel has a chance to disassemble. Recent advancements in laser technology, particularly with the development of more powerful and efficient lasers like those at the National Ignition Facility (NIF), coupled with improvements in target fabrication, have brought ICF closer to achieving sustained ignition, a critical milestone where the energy produced by fusion exceeds the energy delivered by the lasers.
The physics underpinning ICF is complex, involving intricate interactions between the laser energy, the ablating material surrounding the fuel pellet, and the resulting plasma. Achieving a perfectly spherical implosion is paramount; any asymmetry can lead to instability and prevent the fuel from reaching the necessary density and temperature for ignition. Scientists are actively researching advanced target designs, including layered targets and structured surfaces, to improve energy coupling and implosion symmetry. Furthermore, the development of advanced diagnostics, such as X-ray imaging and particle detectors, is crucial for understanding the dynamics of the implosion process and identifying areas for optimization.
These diagnostics provide valuable data for validating and refining sophisticated computer simulations that model the complex physics of ICF. One of the major challenges in ICF is achieving efficient energy coupling between the driver (lasers or ion beams) and the fuel. A significant portion of the energy is lost during the ablation process, where the outer layers of the target are vaporized to drive the implosion. Researchers are exploring various strategies to improve energy coupling, such as using shorter wavelength lasers, which are more efficiently absorbed by the target material, and employing advanced pulse shaping techniques to optimize the laser pulse profile.
Another approach involves using ion beams as the driver, which can potentially deliver energy more efficiently to the fuel. However, ion beam driven ICF presents its own set of technological challenges, including the development of high-intensity ion sources and focusing systems. Beyond the technological hurdles, the pursuit of ICF ignition also pushes the boundaries of fundamental plasma physics. Understanding and controlling plasma instabilities, such as the Rayleigh-Taylor instability, which can disrupt the implosion process, is crucial for achieving sustained fusion reactions.
Advanced simulations and experiments are being conducted to study these instabilities and develop mitigation strategies. The data obtained from these studies not only benefits ICF research but also contributes to a broader understanding of plasma behavior in extreme conditions, relevant to astrophysics and other areas of physics. Furthermore, the development of advanced materials that can withstand the intense radiation and particle fluxes generated during ICF experiments is essential for building robust and reliable reactor components.
While significant progress has been made in recent years, achieving commercially viable ICF power plants remains a long-term goal. The current focus is on demonstrating sustained ignition and net energy gain, which would pave the way for future development of more efficient and cost-effective ICF reactor designs. The potential benefits of ICF, including a virtually limitless supply of clean energy and the absence of long-lived radioactive waste, make it a compelling area of research and development in the quest for a sustainable energy future. The innovations in laser technology, target fabrication, and plasma physics driven by ICF research are also likely to have broader applications in other fields, such as materials science and medical imaging.
Magnetized Target Fusion: Bridging the Gap
Magnetized target fusion (MTF) presents a compelling hybrid approach, merging the strengths of both magnetic and inertial confinement fusion. By leveraging the stability offered by magnetic fields and the rapid heating achieved through compression, MTF aims to ignite fusion reactions with significantly lower driver energies than traditional inertial confinement fusion (ICF). This innovative approach involves compressing a pre-magnetized plasma target, typically a cylindrical liner, using various drivers such as magnetic pressure or converging shock waves.
The magnetic field within the target plays a crucial role, insulating the hot plasma from the liner walls, thereby reducing energy loss and improving confinement efficiency. This allows MTF to potentially achieve fusion with smaller, less powerful, and more cost-effective drivers. One of the key advantages of MTF lies in its potential to overcome the limitations faced by both magnetic and inertial confinement approaches. While tokamaks and stellarators grapple with maintaining plasma stability over long durations, and ICF struggles with achieving symmetrical implosions, MTF offers a middle ground.
The pre-existing magnetic field within the target enhances stability during compression, mitigating the risk of disruptive instabilities. Furthermore, the compression process itself is less sensitive to asymmetries compared to ICF implosions, increasing the robustness of the fusion process. Several promising MTF concepts are currently being explored, including liner compression using pulsed power generators, magnetic flux compression, and the use of converging shock waves driven by powerful lasers or particle beams. For instance, the General Fusion company is pioneering a magnetized target fusion approach using pneumatically driven pistons to compress a magnetized plasma target.
This method involves injecting a plasma vortex into a liquid metal cavity and then rapidly compressing it using synchronized pistons. The resulting pressure increase heats and compresses the plasma, potentially reaching fusion conditions. Other approaches, like those being researched at Los Alamos National Laboratory, utilize high-powered pulsed magnetic fields to implode cylindrical metal liners onto a magnetized plasma target. These diverse research efforts highlight the growing interest and investment in MTF as a viable pathway towards achieving practical fusion energy.
The pursuit of MTF research also benefits from advancements in areas such as pulsed power technology, high-energy lasers, and sophisticated plasma diagnostics. As these technologies continue to mature, MTF experiments can achieve higher pressures, temperatures, and confinement durations, bringing us closer to the crucial milestone of net energy gain. The potential of MTF to deliver a more efficient and cost-effective route to fusion energy makes it a critical area of focus in the global quest for clean and sustainable power.
Plasma Confinement and Heating: Taming the Extreme
Achieving the extreme temperatures necessary for nuclear fusion, reaching tens of millions of degrees Celsius, presents a formidable challenge in plasma physics. This extreme heat transforms atoms into a chaotic state of freely moving ions and electrons, forming plasma. Confining and heating this plasma to fusion-relevant conditions requires cutting-edge technologies and a deep understanding of plasma behavior. One of the primary methods for confinement involves powerful magnetic fields, essentially creating an invisible bottle to contain the superheated plasma and prevent it from contacting the reactor walls, which would cause cooling and contamination.
Innovations in superconducting magnets are crucial here, as they enable the generation of incredibly strong magnetic fields with significantly reduced energy consumption compared to conventional electromagnets. These advancements are pushing the boundaries of plasma confinement, enabling researchers to explore new reactor designs like stellarators, which utilize complex, twisted magnetic fields generated by external coils to achieve greater plasma stability. Radio frequency (RF) heating plays a vital role in achieving and maintaining these extreme temperatures. By employing electromagnetic waves at specific frequencies, analogous to a microwave oven, energy is transferred to the plasma, increasing its thermal energy.
Different RF heating techniques target specific plasma particles, allowing for precise control over the heating process and optimization for different reactor designs. For instance, ion cyclotron resonance heating (ICRH) targets ions, while electron cyclotron resonance heating (ECRH) targets electrons, offering fine-tuned control over the plasma’s energy distribution. These advancements in RF heating are essential for reaching ignition, the point at which the fusion reaction becomes self-sustaining. Another critical technology for heating and fueling fusion plasmas is neutral beam injection (NBI).
This technique involves accelerating beams of neutral atoms to extremely high velocities and injecting them into the magnetically confined plasma. As these neutral atoms collide with the plasma particles, they transfer their kinetic energy, further heating the plasma and providing a source of fuel for the fusion reaction. Neutral beam injection also plays a crucial role in driving plasma current, which is essential for maintaining the magnetic confinement configuration in tokamak reactors. The development of high-energy neutral beams is continuously evolving, with ongoing research focused on increasing beam power and efficiency to maximize plasma heating and current drive capabilities.
The interplay of these heating and confinement techniques, along with advanced diagnostics and control systems, is paving the way for achieving net energy gain in nuclear fusion reactors, marking a critical step towards a clean and sustainable energy future. Beyond these established methods, researchers are actively exploring innovative heating and confinement strategies. One promising area is the development of advanced materials for reactor walls that can withstand the extreme conditions of a fusion environment. These materials must be able to tolerate high heat fluxes, neutron bombardment, and intense magnetic fields while minimizing plasma contamination.
Furthermore, novel magnetic confinement concepts, such as the compact spherical tokamak and the field-reversed configuration, offer potential advantages in terms of stability and efficiency. These advancements, coupled with continuous improvements in plasma diagnostics and control algorithms, are pushing the boundaries of fusion research, bringing us closer to the realization of a fusion-powered future. The pursuit of net energy gain, a crucial milestone in fusion energy research, relies heavily on optimizing the delicate balance between plasma confinement and heating.
Achieving and sustaining the necessary conditions for fusion require precise control over the plasma’s temperature, density, and confinement time. The development of advanced diagnostics, such as Thomson scattering and interferometry, provides researchers with detailed insights into the plasma’s properties, enabling real-time monitoring and control. As these technologies continue to evolve, they will play an increasingly important role in understanding and mitigating plasma instabilities, ultimately paving the way for sustained fusion reactions and a clean energy future.
Plasma Stability: The Key to Sustained Fusion
Plasma stability stands as a cornerstone in the quest for sustained nuclear fusion reactions. Achieving the extreme temperatures and pressures necessary for fusion requires confining the superheated plasma within powerful magnetic fields, a feat analogous to containing lightning in a bottle. However, this volatile state is prone to instabilities—disruptions that can cause the plasma to escape confinement, cooling rapidly and extinguishing the fusion process. These instabilities represent a significant hurdle in the pursuit of net energy gain, making their detection and mitigation critical for the success of future fusion reactors.
Advanced diagnostics and control systems are being developed to address this challenge, aiming to predict, prevent, and suppress these disruptive events. Tokamaks, the leading fusion reactor design, utilize a toroidal magnetic field to confine the plasma, but their inherent limitations make them susceptible to certain types of instabilities. Stellarators, with their more complex, twisted magnetic fields generated by external coils, offer an intrinsic advantage in terms of stability. This stems from the carefully optimized geometry of the stellarator’s magnetic coils, which creates a more stable magnetic topology and reduces the likelihood of plasma disruptions.
Researchers are exploring innovative coil designs and control algorithms to further enhance the stability of stellarator plasmas, paving the way for steady-state fusion operation. Inertial confinement fusion (ICF), while not relying on continuous magnetic confinement, also faces stability challenges. The symmetrical implosion of the fuel pellet is crucial for achieving the necessary densities and temperatures for ignition. Any asymmetries in the implosion process, driven by imperfections in the target or laser beams, can lead to instabilities that disrupt the compression and reduce the fusion yield.
Advanced target fabrication techniques and precision laser control systems are being developed to mitigate these instabilities and improve the efficiency of ICF implosions. These advancements are pushing ICF closer to achieving ignition and demonstrating the potential of this approach for energy production. Magnetized target fusion (MTF), a hybrid approach combining elements of magnetic and inertial confinement, also benefits from enhanced plasma stability. The pre-magnetized target plasma offers greater resilience against instabilities during compression, allowing for more efficient energy coupling from the imploding liner.
This approach potentially lowers the driver energy requirements compared to traditional ICF, making MTF an attractive pathway towards commercially viable fusion energy. Research in MTF focuses on optimizing the initial magnetization of the target and the compression dynamics to maximize fusion yield and energy gain. The development of sophisticated diagnostic tools plays a vital role in understanding and controlling plasma instabilities. Advanced techniques like Thomson scattering, interferometry, and fast cameras provide real-time measurements of plasma parameters such as temperature, density, and magnetic field fluctuations. These measurements enable researchers to identify the precursors to instabilities and develop feedback control systems that can actively stabilize the plasma. Machine learning algorithms are being employed to analyze the vast amounts of data generated by these diagnostics, allowing for faster and more precise detection and mitigation of disruptive events. These advances in plasma control are essential for achieving sustained fusion reactions and realizing the promise of clean, abundant fusion energy.
The Pursuit of Net Energy Gain
The ultimate goal of fusion research is to achieve net energy gain—producing more energy from the fusion reaction than is required to initiate and sustain it. This milestone, often referred to as “ignition,” represents the point at which self-sustaining fusion reactions become possible, paving the way for commercially viable fusion power plants. Recent experiments, particularly with inertial confinement fusion at the National Ignition Facility (NIF) and in magnetic confinement fusion experiments like JET and SPARC, have demonstrated significant progress, inching closer to this critical threshold.
Reaching ignition is not just a scientific achievement; it’s a crucial step towards addressing the world’s growing energy demands with a clean and sustainable source. The pursuit of net energy gain hinges on overcoming several complex scientific and engineering challenges. One key aspect is maximizing the efficiency of plasma confinement, ensuring that the superheated plasma, where fusion reactions occur, is held together long enough for a substantial number of fusion events to take place. Advanced magnetic confinement systems, like those being developed for stellarators and next-generation tokamaks, utilize sophisticated coil designs and feedback control systems to optimize plasma stability and confinement time.
Similarly, inertial confinement fusion experiments are pushing the boundaries of laser precision and target fabrication to achieve higher implosion velocities and densities, creating the extreme conditions necessary for ignition. Another critical factor is achieving high plasma temperatures and densities. Fusion reactions occur at tens of millions of degrees Celsius, requiring innovative heating methods like radio frequency heating and neutral beam injection. Further advancements in these technologies, combined with improved plasma confinement, are essential for reaching the required conditions for sustained fusion.
The development of high-temperature superconducting magnets is also playing a crucial role, enabling stronger magnetic fields for improved plasma confinement and performance. These advancements, driven by international collaborations and cutting-edge research, are continuously pushing the boundaries of plasma physics and engineering. Beyond the technical hurdles, achieving net energy gain also involves significant engineering challenges related to the design and operation of fusion reactors. These include developing materials that can withstand the extreme temperatures and neutron fluxes produced during fusion reactions, designing efficient heat extraction systems to convert the fusion energy into usable electricity, and developing robust tritium breeding blankets to ensure a continuous fuel supply for the fusion process.
For example, research into liquid metal blankets and advanced divertor designs is crucial for managing the intense heat and particle fluxes in future fusion power plants. The progress made in recent years, such as the record-breaking fusion energy yield achieved at the NIF in 2022, demonstrates the potential of fusion energy. While significant challenges remain, the ongoing advancements in plasma physics, materials science, and engineering are paving the way for a future where fusion becomes a primary source of clean, safe, and abundant energy. The continued international collaboration and investment in fusion research are essential to achieving this goal, ensuring a brighter future powered by the very process that fuels the stars.
International Collaboration: Fueling Progress
International collaborations are the cornerstone of modern nuclear fusion research, enabling scientists and engineers to pool resources, share expertise, and accelerate progress towards achieving sustainable fusion energy. Projects like ITER (International Thermonuclear Experimental Reactor) in France, a large-scale tokamak experiment, exemplify this collaborative spirit. ITER alone involves contributions from China, the European Union, India, Japan, Korea, Russia, and the United States, each providing critical components and expertise to the project. This pooling of resources is not limited to tokamaks; stellarator research also benefits immensely from international partnerships, with facilities like the Wendelstein 7-X in Germany involving researchers from around the globe.
These collaborations are not merely symbolic; they are essential for tackling the immense scientific and engineering challenges inherent in fusion reactor design and operation. One of the key benefits of international collaboration lies in the sharing of knowledge and best practices across different research groups. Plasma physics, at its core, is an incredibly complex field, and no single nation possesses all the expertise required to solve the myriad challenges associated with achieving net energy gain.
Through joint experiments, data sharing agreements, and researcher exchange programs, scientists can learn from each other’s successes and failures, accelerating the overall pace of innovation. For example, advancements in plasma diagnostics developed in Japan might be readily adopted and implemented in experiments in the United States or Europe, leading to a more rapid understanding of plasma behavior and improved control strategies. Furthermore, international partnerships facilitate the development of advanced technologies essential for fusion reactors. The construction of ITER, for instance, requires the development of cutting-edge superconducting magnets capable of producing extremely strong magnetic fields, as well as sophisticated plasma heating and diagnostic systems.
These technological advancements often have applications beyond fusion energy, contributing to progress in other fields such as materials science, high-performance computing, and advanced manufacturing. The economic benefits of these technological spillovers can be substantial, further justifying the investment in international fusion research. Beyond the large-scale projects, smaller, more focused collaborations play a crucial role in advancing specific areas of fusion research. These collaborations might involve universities, national laboratories, and private companies working together to address specific challenges, such as improving the efficiency of inertial confinement fusion targets or developing novel materials for reactor components.
These targeted partnerships allow for a more agile and responsive approach to innovation, complementing the larger, more structured international projects. The sharing of data and results from these smaller collaborations contributes to a more comprehensive understanding of the physics and engineering challenges involved in achieving fusion energy. Ultimately, the pursuit of fusion energy is a global endeavor, requiring the collective efforts of scientists, engineers, and policymakers from around the world. By fostering international collaboration, we can accelerate the development of this clean, sustainable, and virtually limitless energy source, paving the way for a future powered by fusion. The complex interplay of science, technology, and international cooperation is essential to overcome the remaining hurdles and realize the full potential of nuclear fusion as a transformative energy solution.
A Fusion-Powered Future
Advanced fusion reactor designs represent a paradigm shift in energy production, promising a clean, safe, and virtually limitless power source, fundamentally altering our energy landscape. While the tokamak configuration has dominated research, alternative concepts like stellarators, inertial confinement fusion (ICF), and magnetized target fusion (MTF) are gaining traction due to their potential to overcome inherent limitations of the tokamak design. These innovations are not merely incremental improvements; they represent a diversification of strategies in the pursuit of controlled nuclear fusion, each with its own set of technological hurdles and potential rewards.
The successful deployment of any of these reactor designs would dramatically reduce our reliance on fossil fuels and mitigate the effects of climate change, ushering in an era of energy abundance. Stellarators, with their complex, three-dimensional magnetic fields, offer an inherently stable plasma confinement compared to tokamaks, which are susceptible to disruptions. The Wendelstein 7-X stellarator in Germany, for instance, has demonstrated impressive plasma confinement times, paving the way for more stable and efficient fusion reactors.
This stability is crucial for achieving sustained fusion reactions and ultimately, net energy gain. While the construction of stellarators is more challenging due to the intricate coil designs, the promise of inherent stability makes them a compelling alternative to tokamaks. Ongoing research focuses on optimizing stellarator designs to improve plasma performance and reduce construction costs. Inertial confinement fusion (ICF) facilities, such as the National Ignition Facility (NIF) in the United States, use powerful lasers to compress and heat tiny fuel pellets to extreme densities and temperatures, creating conditions necessary for fusion.
Recent experiments at NIF have demonstrated significant progress towards achieving ignition, a critical milestone where the fusion reaction becomes self-sustaining. While challenges remain in achieving consistent and high-yield fusion reactions, advancements in laser technology, target fabrication, and plasma diagnostics are continuously improving the performance of ICF experiments. The potential of ICF lies in its ability to achieve very high energy densities, albeit in short bursts. Magnetized target fusion (MTF) bridges the gap between magnetic and inertial confinement, offering a potentially more energy-efficient pathway to fusion.
MTF devices compress a pre-heated and magnetized plasma to fusion conditions, requiring less energy than pure ICF. Several MTF concepts are under development, each with its own approach to plasma compression and heating. The appeal of MTF lies in its potential to achieve fusion with relatively smaller and less expensive facilities compared to tokamaks or ICF facilities. However, significant research is still needed to demonstrate the viability of MTF as a fusion energy source. Ultimately, the pursuit of net energy gain remains the central objective of all fusion research endeavors.
Recent advances across various reactor designs, coupled with innovations in plasma physics, materials science, and engineering, are steadily moving us closer to this critical milestone. The ITER project, while based on the tokamak design, will provide invaluable data and experience for future fusion reactors, regardless of their specific configuration. The convergence of scientific progress, technological innovation, and international collaboration is fueling the momentum towards a future powered by fusion, a future where clean, sustainable energy is readily available to all.