A team of scientists has achieved a major breakthrough in fusion energy technology. They have built a first-of-its-kind fusion experiment using permanent magnets. This is a surprisingly simple technique that could potentially dramatically reduce the cost of future fusion power plants.
     The team is based at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL). They have pioneered a new design for a type of fusion machine called a stellarator.
     Stellarators use complex magnetic fields to confine plasma which is the superheated state of matter needed to fuel the fusion reactions that power the Sun and stars. If it is possible to harness on Earth, fusion could offer an abundant source of clean energy.
     Stellarators and tokamaks are both devices designed to use magnetic fields to contain the incredibly hot plasma needed for nuclear fusion.
     The key difference between the two types of fusion reactors lies in how they create the magnetic field that keeps the plasma in place. Tokamaks utilize a powerful electric current flowing through the plasma itself, along with external coils. Stellarators rely solely on complex, twisted magnetic coils to shape the field. This makes stellarators inherently more stable than tokamaks. This means that they are suitable for continuous operation. However, tokamaks are currently better at maintaining high temperatures in the plasm. Scientists hope to use stellarators as power plants in the future if they can replicate the fusion process that occurs within stars like our Sun.
     Existing stellarators create their complex magnetic fields with precisely constructed and expensive electromagnets. However, the PPPL team’s innovative device, called MUSE, employs a different approach. Instead of electromagnets, the PPPL stellarators rely on permanent magnets. These magnets the same kind that adorn refrigerators. This approach drastically simplifies construction.
     Graduate student Tony Qian, whose research was key to MUSE’s development, said, “Using permanent magnets is a completely new way to design stellarators. This technique allows us to test new plasma confinement ideas quickly and build new prototypes easily,”
     MUSE’s clever design isn’t just about how much it costs. Scientists theorized that permanent magnets could be used in this way. However, it took decades for someone to pull it off. Michael Zarnstorff is a senior research physicist at PPPL. He first realized the potential in 2014. “I realized…permanent magnets could generate and maintain the magnetic fields necessary to confine the plasma so fusion reactions can occur,” he reveals.
     Stellarators hold a significant advantage over a popular alternative fusion machine design known as a tokamak. Tokamaks also use magnetic fields. However, they rely on electric currents flowing within the plasma itself. Those currents can be unstable which makes fusion reactions harder to sustain. Stellarators don’t have this issue and this allows them to run continuously.
     The problem is that the magnets currently used in stellarators’ have been notoriously difficult to design and manufacture. This engineering challenge has relegated the stellarator design to an underdog position despite its potential edge. MUSE could change the game entirely with its readily available, easily shaped magnets.
     MUSE’s design embodies a crucial property called quasi-symmetry. This means that even though the stellarator’s shape might look irregular, the strength of its magnetic field is very consistent throughout. This uniformity helps keep the plasma neatly contained. This, in turn, makes fusion more likely. MUSE is designed to be superbly quasi-symmetrical. This makes it far more stable than earlier stellarator models.

     The PPPL team is now preparing for experiments to study MUSE’s quasi-symmetry. They are hoping it will provide crucial insight into how well it will actually perform. Ultimately, MUSE’s success offers a glimpse into a future where fusion power plants are more affordable and accessible. Permanent magnets will play a starring role in this clean energy revolution.

     Longview Fusion Energy Systems has contracted U.S. engineering and construction firm Fluor Corporation to design the world’s first commercial laser fusion power plant.
     Longview said, “Fluor will leverage its global experience in developing and constructing complex, large-scale facilities to provide preliminary design and engineering to support the development of Longview’s fusion-powered plant.”
     Longview noted that, unlike other approaches, it does not need to build a physics demonstration facility, and, with its partner Fluor, “can focus on designing and building the world’s first laser fusion energy plant to power communities and businesses”.
     The historic breakthroughs in fusion energy gain at the Lawrence Livermore National Laboratory’s (LLNL) National Ignition Facility (NIF) have enabled their project.
     Nuclear fusion is the process by which two light nuclei combine to form a single heavier nucleus. A huge amount of energy is released during fusion. LLNL has been pursuing the use of lasers to induce fusion in a laboratory setting since the 1960s. They built a series of increasingly powerful laser systems at the California lab and created the National Ignition Facility (NIF), described as the world’s largest and most energetic laser system. The NIF uses high-power laser beams to create temperatures and pressures similar to those found in the cores of stars and giant planets – and inside nuclear explosions.
     On 5 December of 2022, the NIF achieved the first ever controlled experiment to produce more energy from fusion than the laser energy used to drive the reaction. The experiment utilized one hundred and ninety-two laser beams to deliver more than two million joules of ultraviolet energy to a deuterium-tritium fuel pellet to create so-called fusion ignition – also referred to as scientific energy breakeven. In achieving an output of three point one five megajoules of fusion energy from the delivery of two point zero five megajoules to the fuel target. The experiment demonstrated the fundamental science basis for inertial confinement fusion energy (IFE) for the first time.
     Longview says it is the only fusion energy company using this verified approach. Its power plant designs include commercially available technologies from the semiconductor and other industries. Longview says that this is to ensure the delivery of carbon-free, safe, and economical laser fusion energy to the marketplace within a decade.
      Valerie Roberts is Longview’s Chief Operating Officer and former National Ignition Facility construction/project manager. She said, “We are building on the success of the NIF, but the Longview plant will use today’s far more efficient and powerful lasers and utilize additive manufacturing and optimization through AI.”
     Edward Moses is Longview’s CEO and former director of the NIF. He added, “Laser fusion energy gain has been demonstrated many times over the last 15 months, and the scientific community has verified these successes. Now is the time to focus on making this new carbon-free, safe, and abundant energy source available to the nation as soon as possible.”
     In April of 2023, Fluor signed a memorandum of understanding with Longview to be its engineering and construction collaborator in designing and planning laser fusion energy commercialization.
     Longview’s plan is for the development of laser fusion power plants. They will have the capacity of up to sixteen hundred MW to provide electricity or industrial production of hydrogen fuel and other materials that can help to decarbonize heavy industry.

     Most people know about solids, liquids, and gases as the three main states of matter. However, there is a fourth state of matter as well. Plasma, which is also known as ionized gas, is the most abundant, observable form of matter in our universe. It is found in our Sun and other celestial bodies.
     Creating the hot mix of freely moving electrons and ions that compose a plasma often requires extreme pressures and/or temperatures. In these extreme conditions, researchers continue to discover the unexpected ways that a plasma can move and evolve.
     By gaining a better understanding of the motion of plasma, scientists gain valuable insights into solar physics, astrophysics, and fusion.
     In a report published in Physical Review Letters, researchers from the University of Rochester, along with colleagues at the University of California, San Diego, discovered a new class of plasma oscillations. These are back-and-forth, wave-like movements of electrons and ions. These findings have implications for improving the performance of miniature particle accelerators and reactors used to create fusion energy on earth.
     John Palastro is a senior scientist at the Laboratory for Laser Energetics, an assistant professor in the Department of Mechanical Engineering, and an associate professor at the Institute of Optics. He said, “This new class of plasma oscillations can exhibit extraordinary features that open the door to innovative advancements in particle acceleration and fusion.”
     One of the important properties that characterizes a plasma is its ability to support collective motion, with electrons and ions moving in unison.
     These oscillations are similar to a rhythmic dance. In the same way as dancers respond to each other’s movements, the charged particles in a plasma interact and oscillate together, creating a coordinated motion.
     The properties of these oscillations have previously been linked to the properties such as the temperature, density, or velocity of the plasma as a whole.
     However, Palastro and his colleagues have determined a theoretical framework for plasma oscillations where the properties of the oscillations are completely independent of the plasma in which they exist.
     Palastro says, “Imagine a quick pluck of a guitar string where the impulse propagates along the string at a speed determined by the string’s tension and diameter. We’ve found a way to ‘pluck’ a plasma, so that the waves move independently of the analogous tension and diameter.”
     In their theoretical framework, the amplitude of the oscillations could be made to travel faster than the speed of light in a vacuum or stop completely, while the plasma itself travels in an entirely different direction. This research has a variety of promising applications. One of most important applications would be in helping to achieve clean-burning, commercial fusion energy.
     Coauthor of the report, Alexey Arefiev, is a professor of mechanical and aerospace engineering at the University of California, San Diego. He says, “This new type of oscillation may have implications for fusion reactors, where mitigating plasma oscillations can facilitate the confinement required for high-efficiency fusion power generation.”
     Dozens of companies world-wide are working on a variety of designs for fusion power reactors. Hopefully, the work of John Palastro and others will speed the development of fusion power.

     Nuclear fusion is the process of generating energy by fusing two atomic nuclei to form a heavier one. It has long been advertised as the energy of the future. Referred to as the “power of the stars,” fusion energy offers clean, safe, and virtually limitless power.
     Achieving fusion on Earth has been notoriously difficult given the challenges of confining the super-hot plasma. Tokamaks are one of the most promising ways to achieve controlled nuclear fusion. These devices utilize magnetic fields to confine hot plasma in the shape of a donut.
     Oxford-based Tokamak Energy announced that it was developing new laser measurement technology. This new technology will transform future commercial fusion power plants and the delivery of clean energy to the grid by controlling extreme heat and pressure within the power plants.
     Inside the donut-shaped vacuum chambers of tokamaks where fusion reactions occur, plasma temperatures rise to over one hundred million degrees Celsius. Stabilizing this extremely hot plasma is vital to maintaining fusion conditions.
     Tokamak Energy’s new laser-based dispersion interferometer system will measure the density of the hydrogen isotopes within the plasma. The company is confident that this cutting-edge technology will help sustain fusion reactions and deliver reliable energy to the grid.
     Dr. Tadas Pyragius is a plasma physist at Tokamak Energy said, “Measuring plasma density is key to our understanding and control of the fusion fuel and efficient future power plant operations. A laser beam fired through the plasma interacts with the electrons and tells us the density of the fuel.” Measuring the density is essential to sustain fusion conditions and deliver secure and reliable energy to the grid.
     Pyragius added that “The extreme conditions created by the fusion process mean we need to perfect the laser-based diagnostics technology now to move forward on our mission of delivering clean, secure and affordable fusion energy in the 2030s.
     Tokamak Energy is developing and testing the new laser-based dispersion interferometer system at its Oxford headquarters. In a press release, the company revealed that the interferometer system would be installed on its fusion machine ST40 later this year.
     The ST40 recently broke records to become the first privately owned fusion reactor to achieve a plasma ion temperature of 100 million degrees Celsius. The ST40 also boasts the highest triple product achieved by a private company. The triple product is a measure that is dependent on plasma density, temperature, and confinement. These parameters are crucial for fusion viability on a commercial scale.
     Following its record-breaking achievements in 2022, ST40 undertook a series of hardware upgrades. They include new power supplies and diagnostic systems. In 2923, the company shifted its focus towards refining plasma scenarios in a high-field spherical tokamak to better understand of the fusion process. Tokamak Energy also announce that it had commissioned a Thomson scattering laser diagnostic on their ST40 to provide detailed readings of plasma temperature and density.
     The ST40 will only be back in operation following further upgrades and maintenance. Tokamak Energy remains hopeful of achieving commercial fusion energy delivery in the 2030s.

     Scientists pursuing fusion energy say they have found a way to overcome one of their biggest challenges to date — by using artificial intelligence.
     Nuclear fusion has for decades been promoted as a near-limitless source of clean energy. That would be a game-changing solution to the climate crisis. However, experts have only achieved and sustained fusion energy for a few seconds, and many obstacles remain, including instabilities in the highly complex process.
     There are several ways to achieve fusion energy. The most common involves using hydrogen isotopes as an input fuel and raising temperatures and pressures to extraordinarily high levels in a donut-shaped machine, known as a tokamak, to create a plasma, a soup-like state of matter.
     But that plasma has to be carefully controlled and is vulnerable to “tearing” and escaping the machine’s powerful magnetic fields that are designed to keep the plasma contained.
     Last Wednesday, researchers from Princeton University and the Princeton Plasma Physics Laboratory (PPPL) published a report in the journal Nature that they had found a way to use artificial intelligence (AI) to forecast these potential instabilities and prevent them from happening in real time.
     The team executed their experiments at the DIII-D National Fusion Facility in San Diego. They found that their AI controller could forecast potential plasma tearing up to 300 milliseconds in advance. Without that intervention, the fusion reaction would have ended suddenly.
     A Princeton spokesperson said, “The experiments provide a foundation for using AI to solve a broad range of plasma instabilities, which have long hindered fusion energy.”
     Egemen Kolemen is a professor of mechanical and aerospace engineering at Princeton University and an author of the study. He said that the findings are “definitely” a step forward for nuclear fusion.
     Kolemen said in a recent interview, “This is one of the big roadblocks — disruptions — and you want any reactor to be operating 24/7 for years without any problem. And these types of disruption and instabilities would be very problematic, so developing solutions like this increase their confidence that we can run these machines without any issues.”
     Fusion energy is the process that powers the sun and all the other stars, and scientists have been trying for decades to master it on Earth. It is achieved when two atoms are fused together, releasing huge amounts of energy. It’s the opposite of nuclear fission which relies on splitting atoms to generate heat. Nuclear fission is the current basis of nuclear power.
     Scientists and engineers near the English city of Oxford recently set a new nuclear fusion energy record, sustaining 69 megajoules of fusion energy for five seconds, using just 0.2 milligrams of fuel. That would be sufficient to power roughly twelve thousand households.
     However, that experiment still used more energy as input than it generated. Another team in California managed to produce a net amount of fusion energy in December 2022, in a process called “ignition.” They have replicated ignition three times since.
     Despite the promising progress, fusion energy is a long way from becoming commercially available. Some analysts say that it will arrive too late to provide the pollution free energy needed to stave off worsening impacts of the climate crisis. Climate scientists say those pollution cuts are required this decade.

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     Support for Woskov’s project originally came from the MIT Energy Initiative (MITEI), which in 2008 provided seed money and later a follow-up grant. Woskov continues to pursue ways his technology can advance geothermal energy research. His current support is from the Department of Energy’s Office of Nuclear Science, through Impact Technologies LLC, which funds his laboratory to explore deep borehole storage of radioactive and nuclear wastes. At twenty thousand feet deep, such boreholes would place nuclear waste much farther from the biosphere than is possible with near-earth depositories such as Yucca Mountain. The bottom six thousand five hundred foot of the hole would hold waste, capped with a six thousand five-hundred-foot seal. This sealing layer is currently considered the “weak link” in the process. Woskov is experimenting with melted basalt and the more viscous granite to learn how he can seal the holes with melted rock. This could provide the most secure entombment of the waste products.
     Woskov joined MIT’s Francis Bitter Magnet Laboratory in 1976 before becoming a founding member of the Plasma Fusion Center in 1979. The first thirty years of his MIT tenure was focused heavily on high-power far infrared scattering for measuring energy distribution of fast ions which are the product of fusion reactions. The research project took much longer than anyone anticipated. However, when it eventually found success in Europe on the TEXTOR tokamak reactor, Woskov was left looking for a new direction for his research.
     While still pursuing fusion power, he started exploring some spinoff technologies that could be operational in a matter of years rather than decades. He received one R&D 100 Award after another for a series of projects which included a thermometer for measuring temperatures in high-temperature furnaces; a hazardous waste emissions monitor for incinerators and power plants; and a device to monitor molten metals.  All these experiments used developments in fusion research to address shorter-term problems.
     “Occasionally you have to do something that has a near-term reward,” Woskov says, pointing out that it can be frustrating when you work on something for 30 years without a final product.
     The fact is that long-term nuclear fusion power research has provided the technology for many exciting short-term projects. And Woskov notes with amusement that so much fusion research revolves around protecting materials in fusion devices from being damaged by hot plasma. His current project exploits the high energy of fusion technology to see how effectively it can melt materials.
     Woskov foresees a number of other practical uses for microwave technology. The high-temperature pressures of microwaves could be used to break apart rocks for mining. They could be used to excavate rock to create tunnels and canals. Microwaves could also be used for fracking in place of pressurized water. This would eliminate problems involving the limited supply of water and resulting water contamination.
      “Energy trumps matter,” Woskov claims, excited by how microwave heat and pressure could literally move mountains, or at least pieces of them. For the time being, he’s going to continue melting his way through the earth’s crust, one rock at a time.

Part 1 of 2 Parts
    Paul Woskov is a senior research engineer at MIT’s Plasma Science and Fusion Center (PSFC). He is using a gyrotron, a specialized radio-frequency (RF) wave generator developed for fusion research, to explore how millimeter RF waves can open holes through hard rock by melting or vaporizing it. Drilling deep into hard rock is necessary to access huge geothermal energy resources, to mine precious metals, or explore new options for nuclear waste storage. However, it is a difficult and expensive process. Today’s mechanical drilling technology has serious limitations. Woskov believes that powerful millimeter microwave sources could increase deep hard rock penetration rates by over ten times at a lower cost over current mechanical drilling systems, while providing other practical benefits.
     Woskov says, “There is plenty of heat beneath our feet, something like 20 billion times the energy that the world uses in one year.” However, Woskov notes, most studies of the accessibility of geothermal energy are based on current mechanical drilling technology and its limitations. They do not consider the idea that a breakthrough in drilling technology could make possible deeper, less expensive penetration, opening into what Woskov calls “an enormous reserve of energy, second only to fusion: base energy, available 24/7.”
     Current rotary drilling technology is a mechanical grinding process that is limited by rock hardness, deep pressures, and high temperatures. Specially designed “drilling mud,” pumped through the hollow drill pipe interior, is used to enable deep drilling. It allows the removal of the excess cuttings, returning them to the surface via a ring-shaped space between the drill pipe and borehole wall. The pressure of the mud also keeps the sides of the hole from collapsing. It seals and strengthens the hole in the process. But there is a limit to the pressures such a borehole can withstand.  Typically, boreholes cannot be drilled to a depth beyond 30,000 feet.
      Woskov asks, “What if you could drill beyond this limit? What if you could drill over thirty-three thousand feet into the Earth’s crust?” With his proposed gyrotron technology this depth is theoretically possible.
     Woskov reveals that drilling engineers have a hard time believing his method does not use the costly drilling mud they depend on. But, he explains, with a gyrotron, high-temperature physics takes the place of the mechanical functions of low-temperature mud. It will allow drillers to extract rock matter through vaporization or displace the melt through pressurization. Similarly, the high temperature melted rock will seal the walls of the borehole. The high pressure from the increased temperature will prevent borehole collapse. An increase in temperature in a confined volume will always result in an increase in pressure over local pressure. This means that drillers could maintain the stability of a borehole to greater depths than possible with drilling muds.
     Woskov mentions yet another advantage: “Our beams don’t need to be round. Forces underground are anisotropic — not symmetrical. That is one reason holes collapse. But we can shape our beam to respond to local pressures. You can create an elliptical hole with the major axis corresponding to the anisotropy of the forces, essentially recovering the strength of a round hole in a symmetrical force field.”
     Later this spring, Woskov is planning to move his base of operation from the PSFC to the Air Force Research Lab (AFRL) in Kirkland, New Mexico. This move will take advantage of a microwave source that will allow him to perform experiments at a power level a factor of ten higher than is currently possible in the laboratory at MIT. He would be able to graduate from drilling rocks in the four-to-six-inch range to those in the two-to-four-foot range. He is especially interested in exploring how well the rock can be vaporized. This would only be possible with the higher power available at AFRL.
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     Ultimately, physicists will use the knowledge acquired from JET’s decommissioning to improve how they incorporate recycling into the design of the Spherical Tokamak for Energy Production (STEP). It is a prototype commercial fusion reactor being planned in Britain. The information will also shape future regulation, according to Buckingham.
     JET and ITER are both ‘tokamak’ design fusion reactors, which confine gas in their doughnut-shaped cavities. JET uses powerful magnets to compress a plasma of hydrogen isotopes, ten times hotter than the Sun, until the nuclei fuse. The last time the fusion community decommissioned a comparable device was in 1997. The Tokamak Fusion Test Reactor at Princeton Plasma Physics Laboratory in New Jersey was shut down. Many parts, such as the equipment for injecting hot beams of gas into the reactor, were reused. The site itself was repurposes. The tokamak had to be filled with concrete, cut up and buried.
     JET scientists hope that the decommissioning will leave little overall waste. Buckingham says that the main challenge is to understand where the tritium is and to remove it from materials, including from metal tiles that line the inside of the tokamak. JET engineers will utilize a refurbished robotic system to remove sample tiles for analysis. They will use remotely operated lasers to measure how much tritium is in samples that remain inside the experimental equipment. Like all hydrogen isotopes tritium is a gas that “penetrates all materials. and we need to know exactly how deep the tritium has penetrated”, says Buckingham.
     Studies at JET this year will remove and study sixty wall tiles. They are the first of more than 4,000 components in the facility. Buckingham adds that “We can use this information to move from lab-scale research to industrial-scale processes, to detritiate the many tons of tiles and components which will be removed from JET over the next few years.”
     In order to extract the tritium from metal parts, engineers will heat the components in a furnace before capturing the released isotope in water. Tritium can be removed from the water and turned back into fuel. The leftover materials become low-level waste, the same classification given to radioactive waste made by universities and hospitals. Variations on this process are being tested for other materials such as resins and plastics.
     JET researchers are exploring how to dispose of low-level waste. They also need to deal with the much smaller amount of intermediate-level radioactive waste in which nuclear decay occurs more frequently. Options for those low and intermediate level wastes remaining include re-treating the waste, removing it to special disposal sites or storing it until it decays to lower levels of radioactivity. Some unaffected parts of JET that are not radioactive, such as diagnostic and test equipment, have already been repurposed in fusion experiments in France, Italy and Canada.
     In its final experiments last December, JET was deliberately damaged. Scientists researched inverting the shape of the confined plasma in a way that might more readily confine heat. They also deliberately damaged the facility by sending a high-energy beam of ‘runaway’ electrons careering into the reactor’s inner wall. This beam is produced when plasma is disrupted.
Joelle Mailloux leads the scientific program at JET. He said, “Analysis of the damage, after the machine is opened up, will provide useful data to test the detailed predictions.”

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     Scientists have started to decommission one of the world’s earliest nuclear-fusion reactors, forty years after it began operations. Researchers will study the seventeen-year process of dismantling the Joint European Torus (JET) near Oxford, UK, in unprecedented detail. They will use the knowledge to make sure future fusion power plants are safe and economically viable.
     Rob Buckingham leads the decommissioning for the U.K. Atomic Energy Authority (UKAEA), which oversees JET. He said, “We are starting to think seriously about a fusion power plant This means thinking about the whole plant life cycle.”
     The nuclear fusion of atoms is the process that powers the Sun. If it can be harnessed, it could provide humans with a near-limitless source of clean energy. Creating the conditions for fusion in power plants and exploiting the resulting energy will require complex engineering that hasn’t yet been developed. Some researchers think that this means that commercial fusion power is still many decades away. However, some of the organizations researching nuclear fusion are estimating commercial nuclear fusion reactors arriving in the next five to ten years.
    Researchers are moving ahead with designs for the first commercial fusion reactors as excitement about fusion power grows. In 2022, JET broke the record for the amount of energy created through fusion. And the U.S. National Ignition Facility (NIF) in Livermore, California now routinely generates more energy from a fusion reaction than was put in. The NIF calculations do not include the entire energy requirements of running the facility. Fusion plants would need to exceed this level of energy expended to truly ‘break even’, but physicists have celebrated the milestones.
     JET is important because the facility is a test bed for ITER which is a twenty-two billion dollar fusion reactor being constructed near Saint-Paul-lez-Durance, France. ITER aims to prove the feasibility of fusion as an energy source in the 2030s. Jet has assisted decisions on what materials to build ITER with and the fuel it will use. JET has been crucial to predicting how the bigger experiment will behave.
     The most difficult part of decommissioning the JET site will be dealing with its radioactive components. The process of nuclear fusion does not generate waste that is radioactive for millennia, unlike nuclear fission which powers today’s nuclear reactors. But JET is among the small number of experimental fusion facilities worldwide that have used significant amounts of tritium which is a radioactive isotope of hydrogen. Tritium, which will be used as a fuel in some future fusion plants including ITER, has a half-life of 12.3 years. Its natural radiation, alongside the high-energy particles it releases during fusion, can leave reactor components radioactive for decades.
     Anne White is a plasma physicist at the Massachusetts Institute of Technology in Cambridge. She says that decommissioning a fusion experimental facility doesn’t mean “bulldozing everything within sight into rubble and not letting anyone near the site for ages”. Instead, engineers’ priorities will be to reuse and recycle parts when possible. This process will include removing tritium where possible, says Buckingham. Removing tritium reduces radioactivity and allows tritium to be reused as fuel. “The sustainable recycling of this scarce resource makes economic sense,” he says.
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     Research plasma railguns are typically operated in a vacuum and not at ambient air pressure. Plasma railguns are valuable because they can produce muzzle velocities of up to several hundred kilometers per second. Because of this characteristic, plasma railguns have applications in magnetic confinement fusion (MCF), magneto-inertial fusion (MIF), high energy density physics research (HEDP), laboratory astrophysics, and as a plasma propulsion engine for spacecraft.
     Linear plasma railguns put extreme demands on their insulators because they must be an electrically insulating, plasma-facing vacuum component which can survive both thermal and acoustic shocks. In addition, a complex triple joint seal may exist at the breech of the bore. This can often pose an extreme engineering challenge.
     The NearStar nuclear fusion reactor has rails which are about a hundred feet long. They fire a fuel capsule with a mix to deuterium and tritium gas at six mile per second into a twenty-foot square reaction chamber. An approximately two-foot field coil with a small hole in the center is located inside the reaction chamber. As each pellet of fuel passes through the hole in the center of the coil, an extreme magnetic field crushes it and produces a flash of fusion. A heat exchanger circulates a liquid molten salt through the walls of the fusion chamber which is heated by each fusion reaction. The heat exchanger produces steam which spins a turbine to generate electricity. Improvements in the design of the plasma railgun could allow the future use of advanced fusion fuels, lowering cost and improving efficiency.
     In addition to its use in commercial fusion energy reactors, the plasma railgun could be used as a test bench for the development of advanced nuclear fusion propulsion systems for spacecraft.
     There is another advantage to the railgun approach. If nuclear fusion is achieved via inertial confinement with laser bombardment, the use of high-end lasers will require that highly technical staff will have to operate the power plant. On the other hand. NearStar believes that a powerplant that uses railguns could be operated by upskilled car mechanics and maintenance workers. This would definitely be a better proposition from a commercial perspective.
     NearStar has a handful of people but it is expanding its team to include scientists and engineers. It aims to break even in the next five years. Amit Singh is the CEO of NearStar. He previously worked in a data analytics company. He believes that all the components needed to make commercial nuclear fusion a reality are available. He thinks that the company’s simple approach will help reach that goal sooner rather than later.
     Singh said, “What’s unique about NearStar is that everything we need to build the fusion power plant already exists on planet Earth. So, in a lot of ways, we’re kind of like the Wright brothers — we shouldn’t be the first to flight, but we think we will be because our design and our architecture are so much more simple.”
     In the future, nuclear fusion plants will get smaller. It will be possible to build them under buildings and reduce transmission and distributions losses.