Implementation of the recommended strategic plan for U.S. magnetic fusion energy research will require an expanded organizational structure for the U.S. Department of Energy (DOE) Office of Fusion Energy Sciences (FES) with more deliberate planning, regular opportunities for input from the research communities, coordination of research efforts in burning plasma science, materials science, fusion nuclear science and technology, and the engineering sciences needed to realize an economical pathway to fusion electricity for the nation.
Three primary organizational and program changes are described below: (1) a new division within the DOE/FES, (2) adoption of a long-range strategic plan, and (3) strong engagement from the fusion energy science research community. The expanded organizational and program management structure within the DOE/FES is needed to emphasize burning plasma science in preparation of International Thermonuclear Experimental Reactor (ITER) studies and to coordinate the research and technology within a growing national program that looks beyond ITER. Importantly, this structure enables the comprehensive, long-range plan that is needed to carry out the accompanying research aimed at a low-cost compact fusion pilot plant. This includes support for the fusion technologies that will enable a compact, low-cost pathway to fusion demonstration and strengthening communication with the multi-disciplinary research communities.
Comments are also made regarding (1) safety and licensing standards for fusion energy research facilities, (2) the health of the U.S. fusion research program, (3) the importance of continued participation in the larger international effort, (4) the need to encourage growth of private sector capabilities in fusion energy technology, (5) the
value of cross-disciplinary partnerships in related science and technology efforts, and (6) the importance of public outreach to better communicate the long-term potential for economical fusion energy and to better engage students and educational institutions in the integrated science, technology, engineering, and mathematics at the foundation of fusion energy science.
This chapter concludes with six findings and seven recommendations aimed to guide the implementation of an expanded DOE/FES research program and strengthen community participation in the burning plasma science, materials science, fusion nuclear sciences, and engineering sciences needed to realize an economical pathway to fusion electricity for the nation
The pathway ahead for fusion development requires augmentation of ongoing burning plasma research with the technology and engineering research required to enable fusion power systems. As discussed in Chapter 2, in the last 10 years, many of the complex physical processes of magnetically confined plasma have become understood, and there is growing confidence in the predictions of validated computer simulations and models for burning plasma performance and in the promising new technologies that have the potential for lower-cost approaches to fusion energy. As was also discussed in Chapters 4 and 5, the pathway ahead for fusion development requires augmentation of ongoing burning plasma research with the technology and engineering research required to enable fusion power systems. The demonstration of fusion electricity production will require continued innovations in the technology and engineering needed to sustain the plasma, manage the power exhaust, and take advantage of new technologies to breed tritium fuel and realize innovative approaches to reduce the size of the fusion pilot plant. Progress calls for management and coordination of a multi-disciplinary effort to promote continued innovations in those technologies that will reduce the cost of the fusion development path and to further develop the knowledge, expertise, and infrastructure needed to design a compact fusion pilot plant.
The current organizational structure for the DOE/FES has been adequate to advance to the burning plasma, but is not well suited to accommodate the larger scope. Currently, two divisions exist in DOE/FES: “Research” and “Facilities, Operations, and Projects.” The first has been a generator of ideas and exploration to assess the viability of different magnetic confinement configurations, plasma behavior, and characteristics needed for sustained fusion. The second division attends to the oversight of existing projects. However, the committee finds that the current
structure is not readily adaptable to the expanded science scope and integration of the required sophisticated technologies.
To achieve the necessary focus and coordination, the committee proposes strengthening the organizational structure of the DOE/FES program to better focus on the two goals of the long-term strategy. As discussed in Chapter 3, data and modeling/simulation associated with ITER experiments will provide critical information to design the future pilot plant. Thus, the research division should be re-organized with an explicit focus on burning plasma research as a centerpiece of the division. As noted in Chapter 4, a new fusion technologies division should be added to manage and organize research leading to technologies required to improve and fully enable the fusion power system. Effective coordination between the research, technology, and facilities divisions should be strongly emphasized by DOE/FES leadership.
The goal of this new division would be to manage a portfolio of research tasks including engineering studies of the compact fusion pilot plant that can guide and prioritize research needed to fully establish the science and technology of the fusion power system. The purview of the subgroups within the new DOE/FES division should include, for example, high-temperature superconducting (HTS) magnets, structural materials, blanket, and tritium technologies. The revised organizational structure will facilitate both technical innovation and coordination on interrelated elements within and between DOE/FES divisions.
Ultimately, the realization of fusion energy as a source of electricity will involve the design and construction of complex facilities that rely on continued development of the underlying enabling technologies. Past research facilities for fusion energy science illustrate the significant boosts in capability that result from state-of-the-art advancement of enabling technology. For example, advancement in glass forming technologies were essential for the National Ignition Facility (NIF). Migration of inclusions from the crucibles into the glass had to be overcome, and continuous glass forming techniques had to be developed in order to supply the quantity of high-quality optical glass needed. Similarly, advances in the manufacturing of large niobium-tin (Nb3Sn) superconductors, as discussed in Chapter 2, were essential to the success of the ITER facility and will result in the world’s largest superconducting magnet system.
Looking to the future, continued developments in the underlying enabling technologies are necessary and should be supported. For instance, superconducting magnet technology that can operate at even higher magnetic fields than possible with Nb3Sn conductor will be critical for compact and lower-cost fusion power plants. New manufacturing methods are now able to fabricate complex material structures that may result in extremely beneficial thermal and mechanical properties for fusion applications. Similarly, it is not hard to imagine that materials research is also needed to develop a tritium-breeding blanket in the wall facing the burning plasma.
In short, many transformative and innovative technologies listed in the 2018 report from the DOE’s Fusion Energy Sciences Advisory Committee (FESAC) Subcommittee on Transformative Enabling Capabilities1 may significantly improve the economics of fusion power systems. Strengthened program support within the DOE/FES is needed to support the science and engineering that will lead to the technological leaps necessary for a fusion machine.
The U.S. fusion energy science program needs a long-term strategy that ensures balanced growth and integration, supporting a diversity of program elements that are inherently interlinked through the national fusion energy goal.
Implementation of the strategic expansion recommended in this report will result in a research program that combines burning plasma science, materials science, fusion nuclear science, and the engineering science needed for guiding, designing, and ultimately constructing a compact pilot plant and generating electricity from fusion. The resulting research program in the United States begins with a current focus on burning plasma science and adds research elements that will fully enable a fusion power system. These include engineering of high-field superconducting magnets, fusion nuclear science and the related technologies needed for the components surrounding a burning plasma, and, notably, the fusion “blanket” that can breed tritium fuel and the materials science needed to engineer the structures that can withstand the magnetic forces and neutron irradiation in magnetic fusion energy.
With any burning plasma effort, and especially with the multi-national ITER, the shift to “big science” at the international scale along with national facilities with specific and focused research missions have implications for all areas of the U.S. fusion research community. As noted in the 2004 Burning Plasma report,2 as the U.S. fusion community enters the burning plasma era and ITER operation begins, the scale of even the largest national research facilities effectively become “smaller-scale” programs having specific objectives that will be complementary to ITER. During the next decades, research facilities will continue the trend toward national facilities that, although smaller than ITER, are still addressing essential research tasks in the most cost-effective manner.
The committee’s strategy to realize a fusion plant will require new U.S. research facilities. In fact, the experience in the design, construction, and successful operation of major research facilities in the United States will be critical in both the science mission and in establishing and maintaining global leadership. Successful and efficient completion of new major facilities requires institutional knowledge in the form of experienced scientists and engineers, and cannot be achieved solely by relying on theory or by reading research articles about facilities in other countries.
The adoption of a new strategy for U.S. fusion energy research will necessitate an evolution of major research facilities. These facilities should continue to be world-class and serve the national fusion research community to develop scientific and technical leadership in fusion energy science.
In a well-managed strategy, research priorities would be expected to evolve over time as research questions are answered and tasks are completed, laying the foundation for each new stage. The retirement of facilities that have served their intended purpose and the planning for new machines that will replace them should follow priorities established through a formal structure that includes community-based program reviews and strategic planning. The contributors from university, DOE, and industry research laboratories will give voice to the advances and challenges in their respective institutions that together will inform major decisions as well as the direction of the program more broadly.
An expansion in the DOE/FES to support fusion science and technology beyond the burning plasma science will require coordination among multiple research communities and may include scientific experts from U.S. industry and utilities. The current magnetic fusion energy (MFE) community is largely rooted in academic institutions, with key groups and facilities in nationally funded laboratories, with a growing international involvement through participation in ITER and collaboration on other international facilities. This diverse nature is different in character than, for example, Inertial Confinement Fusion, which is mission-driven by the national laboratories responsible for stockpile stewardship. While there are many able contributors, the expanded research community is only beginning to be unified in the greater vision. To ensure incorporation of innovations and discoveries while making consistent progress toward the long-range fusion energy vision, the committee recommends changes to strengthen community engagement.
The current management structure of the Office of Science allows for input from the research community through advisory boards. These advisory boards are subject to the Federal Advisory Committee Act (FACA) rules, which require providing the public with the opportunity to participate in board meetings, where recommendations are discussed. Each advisory board is composed of approximately 20 individuals, selected for their expertise in the different areas critical to scientific and technical growth and management, including relevant university and laboratory personnel.
DOE’s FESAC is the advisory board for the DOE/FES, and according to its charter, meets and acts only when specifically tasked by the Office of Science to provide advice. FACA rules dictate that FESAC restrict advisory comments to those directly responsive to specific committee charges.
To achieve consistent long-range planning through the FESAC, the committee examined the practices of other advisory committees within the Office of Science to identify those that may serve as a model for DOE/FES. For the DOE Office of Science High Energy Physics Advisory Panel (HEPAP), a subcommittee called the Particle Physics Project Prioritization Panel (P5), was charged with making recommendations on priorities of large facility projects, considering their projected costs. The first P5 report, issued in October 2003, described their role as the “guardian of the facilities roadmap.” P5 is convened approximately every 5 years, including 2008 and 2013, to provide “long-range planning for a 10-year and 20-year global vision.” For DOE/HEPAP, the process of soliciting input from the community works fairly well because P5 prioritization takes that input into account along with fiscal constraints and the need to balance large and medium size projects. DOE/HEPAP has the clear and explicit commitment of the Office of High Energy Physics that the recommended priorities will be honored in funding decisions.
The committee recommends that the DOE/FES ensure the long-range U.S. strategic plan is developed, regularly updated, and vetted by the community through a P5-like process that covers the domestic and international facilities/programs. This effort should engage the professional societies supporting the science and technology for fusion energy, including the American Physical Society Division of Plasma Physics (APS-DPP) and the American Nuclear Society Fusion Energy Division (ANS-FED). In addition, defined events held at regular intervals will bring the U.S. magnetic fusion energy research community together to build a unified national program.
The committee also finds that the magnetic fusion energy research community needs to develop a culture that provides for broad, transparent input to the national program. Self-organized community workshops, or cross-discipline community meetings organized by professional societies, can provide important forums to vet ideas and should be encouraged by the leadership.
A recent successful example of magnetic fusion energy research community engagement is the pair of workshops held in Madison and Austin in 2017 that enabled a long-overdue discussion among members of the plasma science community about collective research priorities and potential pathways to fusion energy. The workshops, organized by the grassroots U.S. Magnetic Fusion Research Strategic Directions3 program committee, were well received by those who participated, and they contributed to the development of a shared vision of the field, although they lacked representation from some disciplines that will be critical to the development of fusion power plants. A strong consensus emerged from the workshops that the science of magnetically confined plasmas has advanced sufficiently that a broadened national effort encompassing the science of fusion energy technologies in addition to burning plasma science is now appropriate.
Another example in this electronic age is the online forum that was established4 by a self-organized group of Early Career Fusion Scientists (ECFS) that took inspiration from the workshops. A poll conducted of the ECFS participants by the group’s leaders shows that group members are strongly motivated in their work by the prospect of fusion energy, and they have expressed enthusiasm for a strategic plan that would unite the community around a roadmap to achieve fusion-based electricity within their lifetimes.
In summary, meaningful coordination and alignment should occur regularly through such activities as FESAC charges to solicit a long-range plan on program/facility priorities and future workshops with significantly broadened participation to include all fields contributing to fusion technology. These activities, coupled with the creation of a new division, are recommended to bring together the creative talent and the management needed for a unified national effort. Together, they should represent the community and enable a prioritization of resources in the most equitable way possible to ensure a vibrant national program.
In addition to the primary management guidance above, the committee also comments on six additional areas: (1) safety and licensing standards for fusion energy research facilities, (2) the health of the U.S. fusion research program, (3) the importance of continued participation in the larger international effort, (4) the need to encourage growth of private sector capabilities in fusion energy technology, (5) the value of cross-disciplinary partnerships in related science and technology efforts, and (6) the importance of public outreach to better communicate the long-term potential for economical fusion energy and to better engage students and educational institutions in the integrated science, technology, engineering, and mathematics at the foundation of fusion energy science.
The pathway toward a compact fusion pilot plant requires one or more research facilities that are capable of safely handling tritium and fusion neutrons, as well as other recognized fusion hazards such as neutron-activated materials, high magnetic fields, and significant thermal, mechanical loads. Siting and licensing strategies for such facilities should be developed well in advance so as not to delay the progress toward the compact fusion pilot plant. It is reasonable to expect that these tritium-capable fusion nuclear research facilities will be owned by DOE and sited at one or more national laboratory. The operation of these facilities under DOE auspices will be an opportunity to provide insight toward future siting and licensing of a compact fusion pilot plant.
The DOE Fusion Safety Standards5,6,7 were developed in the 1990s during the ITER Engineering Design Activity8 in preparation for a potential siting of ITER in the United States. Development of such standards required a multi-year effort with tight collaboration between the main stakeholders, including DOE, the U.S. Nuclear Regulatory Commission (NRC), national laboratories, and industry. The U.S. DOE Fusion Safety Standards were developed with the intention that that they would provide an initial set of requirements and design guidance that could later be used by NRC to develop a fusion regulatory framework for commercial fusion.
As was stated in the 2004 Burning Plasma report (p. 119),9
The well-trained fusion scientist or engineer of the coming decades will require knowledge of concepts and techniques that do not now exist. The hardware and techniques for engineering and scientific research can be expected to change in fundamental ways. Examples involve expected advances in computational techniques, laser and other radiation sources for probing plasmas, sensors, measurement techniques, materials, manufacturing techniques, and so on. Furthermore, many of the scientific concepts used to describe physical phenomena will be qualitatively more sophisticated a decade or two hence. Examples of areas currently undergoing dramatic changes include the modeling of nonlinear processes ranging from plasma heating to magnetic reconnection and models of plasma turbulence and turbulent transport. These and many other areas are likely to change dramatically in the decades of the burning plasma experiment. Thus, the basic training of fusion scientists and engineers in broad areas of physical science and engineering must continue to be an integral part of the fusion program.
The committee has taken notice of the enthusiasm within the U.S. fusion science research community as reflected in the strategic workshops that reported on outstanding recent scientific and engineering progress and an eagerness of early career fusion scientists and engineers to help realize fusion as an energy source. Nevertheless, there is concern that the future health of the U.S. fusion energy sciences program is uncertain. This concern stems from shutting down major experimental facilities (e.g., Alcator C-Mod) and smaller university scale experiments without replacements. This domestic program contraction may be contrasted with new medium and large-scale facilities in Europe and Asia (W7-X, MAST-U, JT60-SA, KSTAR, EAST, WEST, HL-2M). The many contributions from U.S. researchers show a history of innovation. The quality of U.S. research has allowed the nation to remain, until now, a respected peer in the international fusion community. In the future, maintaining a leadership role will require new domestic research facilities that target key questions and a demographically balanced workforce. Furthermore, even though there is widespread community support for
ITER, the United States has yet to prove that it can be a reliable ITER partner, and further delays are likely if the nation does not fulfill its commitments on schedule.
A 2017 white paper on the status of university-based fusion science research submitted by the University Fusion Association (UFA)10 expressed concern that reductions in federal funding for magnetic fusion research at universities, and specifically a contraction in the number of experiments, lead directly to reductions in the training of graduate students. It is further argued that these cutbacks also accelerate the loss of research infrastructure and lead to reticence for university departments to hire new faculty with expertise in this area. Similar concerns were expressed in the 2004 report of the Burning Plasma Assessment Committee11 about the aging of the fusion and plasma science workforce at universities and large fusion facilities; this has been further exacerbated in the years since. The UFA survey results show that the average age of university faculty in the field has increased from 52.7 to 56 in the past 12 years, and up to 30 percent of current faculty anticipate retirement in the next 5 years.
The committee expects that the expansion of scope that DOE/FES recommended in this report will energize university fusion research in several ways. New research initiatives to establish the science basis of fusion energy technology will create opportunities for university innovation, for stable funding to sustain university programs and to inspire the next generation of talented students to become part of the national team. Over the past decades, universities within the United States have, alongside federally funded laboratories, made innovations that advanced magnetic fusion energy plasma science and technology, leading to international recognition of U.S. leadership in the field. In the previous research era when magnetic confinement concepts were evaluated, many universities were able to contribute with moderately sized experimental facilities on site. The practicalities of burning plasma research introduce new constraints on university participation. Future construction of domestic fusion nuclear facilities involving burning plasmas and the safe handling of tritium will be sited at federally funded laboratories due to their larger scale and required specialized safety infrastructure. A unified research effort will require an organizational structure that enables involvement of both laboratory and university personnel in the use and operations of major national facilities. Planning of operations for both national U.S. research facilities and the large international facilities and ITER will require careful consideration to ensure representation and inclusion of contributing groups and broad participation of laboratory and university personnel based at off-site institutions. One approach would be for DOE to provide travel and organizational support for each facility to hold regularly scheduled “collaboration meetings” involving all participants for this purpose. Large high-energy physics experiments such as those at the Large Hadron Collider may serve as an example for inclusive science organizational practices. In addition, the committee notes the value of university scale machines, both for
their advantages in cost-effective investigation of focused research questions and for their hands-on educational value.
When construction is complete, ITER will be the world’s largest research facility and the most significant near-term opportunity for the United States to advance burning plasma science. ITER construction is now more than halfway completed, and the potential benefits to the United States of continued funded participation as an ITER partner are evident. ITER addresses questions about burning plasma science and reactor scale confinement that are essential to progressing toward the goal of fusion power. International collaboration on ITER is a means for the United States to gain answers to these questions as an engaged partner while sharing costs with other participants. Moreover, the standing of the United States in the global fusion community will hinge on fulfillment of its construction commitment as an ITER partner and also the critical engagement of U.S. researchers in support of ITER experiments.12
National benefits as a reliable ITER partner include future opportunities for mutually beneficial international collaborations to make advances in other aspects of the science and technology leading to fusion as an electricity source, including entertaining partnerships on future experiments sited in the United States. As already mentioned, a decision by the United States to withdraw from the ITER partnership would make international collaboration more difficult. Nevertheless, if the United States withdraws from ITER, the United States would still need to pursue other avenues for collaboration and international cost-sharing.
As major new technologies develop and mature, the division of activities between universities, government-funded labs, and the private sector evolves. Considerable development often takes place in universities and national laboratories before commercial enterprise takes off. This is depicted in Figure 6.1 as developed by the 2017 Annual Report of the State of DOE National Laboratories.13 Magnetic fusion energy research is currently in the second stage of technology maturation, called “development.” During the “development” stage, a relatively small fraction of current activity is in the private sector. That proportion will grow in the coming decades, presenting opportunities both to leverage commercial ventures in technology development and to begin preparation for a future fusion power industry.
Since the last burning plasma study in 2004, there has been a substantial increase in private sector fusion energy funding and research. This increase has been of several sorts. First there are the industrial contracts from the DOE issued to
privately held corporations. This is not a new development. The most significant activity is the General Atomics (GA) contract to manage the DIII-D facility. More importantly, perhaps, is that private industry is playing a major role in the construction of U.S. in-kind contributions to ITER. For example, GA is assembling and testing the central solenoid electromagnets. This industrial component of ongoing burning plasma science is significant and will become increasingly important as the U.S. effort progresses toward the construction of a fusion pilot plant. The expertise, developed for the ITER central solenoid in assembling large electromagnets, will expand to include producing very high magnetic fields using rare-earth barium copper oxide (REBCO), superconducting cables
Fusion science and technology research is also pursued in the private sector, both nationally and internationally. The Fusion Industry Association14 is an international coalition of companies working to develop fusion power technologies for the production of electricity. At the present time, the Fusion Industry Association has 16 members and 5 affiliate members. Similar to the professional societies that represent the fusion research community (e.g., the APS Division of Plasma Physics and the ANS Fusion Energy Division), industry associations, like the Fusion Industry Association, can provide important input to implementation of the national fusion research strategy.
One privately funded fusion energy venture is TAE Technologies, with headquarters in Foothill Range, California. TAE Technologies was started nearly two decades ago by University of California, Irvine, physics professor Norman Rostoker. In contrast to mainstream fusion research, TAE concentrates on an alternative magnetic confinement geometry, the field-reversed configuration (FRC). Though FRC confinement performance has not achieved that of tokamaks, the configuration has many attractive engineering features, including simplified divertor geometry and access for maintenance. A new medium-scale FRC experiment, dubbed “Norman” in Rostoker’s honor, was recently constructed and began operation in a single year. A predecessor device achieved confinement that is superior to previous FRC experiments.15,16
The recently announced Commonwealth Fusion Systems,17 with headquarters in Cambridge, Massachusetts, is another privately funded venture. Their goal is to combine proven tokamak physics developed in decades of government-funded fusion research with high-temperature superconducting (HTS) magnet technology to accelerate the path to commercial fusion energy. MIT scientists and engineers are key partners in the Commonwealth effort. Their first technical milestone is successful construction of an HTS fusion magnet, with proposed construction of a compact fusion research device able to explore burning plasma science should that technology development succeed.
All of these companies benefit enormously from the decades of U.S. government-sponsored research that led to their emergence and now train their
workforce, and the fundamental research activities that remain critical before commercialization of fusion takes place. The next phase of commercialization in the United States might take a path similar to those in (1) the space industry with the emergence of SpaceX, Blue-Horizon, and Virgin Galactic and (2) in the nuclear power industry with a substantial entry of smaller, modular advanced fission concepts. The development of fusion power will require increasing participation by private industry, and, in select areas of technology, private industry is now ready to take a larger role.
Mutually beneficial partnerships can maximize information exchange between the public and private sectors by providing tools developed through DOE/FES funding to aid industry development and design, integrating tools from both sectors to provide more complete physics/engineering descriptions, and setting up the framework for each sector to propose and carry out experiments on the other sector’s devices to optimize progress toward development goals. Examples might include
- Parallel private and government-supported R&D on REBCO magnets, with companies and research laboratories contributing complementary strengths.
- DOE-provided access for future private sector development experiments at facilities with safety measures and licensing for tritium and neutrons. Similar cooperative developments are now in place at Idaho National Laboratory, Oak Ridge National Laboratory, and Savannah River National Laboratory.
- FES-provided access and support for the use of simulation and design codes, developed with federal R&D support, to be used by the private sector within the United States to make most effective these important private sector ventures.
- Opportunities for DOE-supported efforts to operate and exploit the science (diagnostics) on future private venture burning plasma machines.
The U.S. fusion community, through a series of workshops and white papers, has concluded that after more than a half-century of plasma physics research, sufficient progress has been made that it is now time to increase attention to engineering and technology-based development. The committee supports this conclusion. Increased industrial involvement in fusion development underscores this transition as well, and this welcome step offers the opportunity for the DOE fusion program to contribute in the form of partnerships and collaborations with industrial projects wherever appropriate. Specific contributions can be made in the form of
access to high-quality simulation tools as well as to special purpose experimental facilities. Intellectual property issues, while important but cumbersome, need to be resolved by mutual negotiations.
The overall conclusion is that increased industrial interest in fusion is a good sign, indicating the readiness to transition to more of a fusion energy focus and to take advantage of new opportunities for collaboration.
Fusion energy science research is interdisciplinary and has resulted in technological and scientific achievements that touch many aspects of everyday life and lead to new insights in related fields such as optics, fluid mechanics, and astrophysics. Fusion research has a long history of “spin-offs” contributing to an impressive assortment of science and technology fields.18 Strong linkages between fusion energy science and related research areas is anticipated in the burning plasma era. Several examples are highlighted below.
For several decades, fusion research has been an important driver for using high-performance computing to describe complex physical systems. Already in 1974, it was realized that simulating the behavior of a fusion plasma required a computer center dedicated to this purpose. This led to the founding of the Controlled Thermonuclear Research Computer Center as the first unclassified supercomputer center in the United States. Its name was later changed to the National Energy Research Supercomputer Center (NERSC), and its mission was expanded to provide computing services to all of the programs funded by the DOE Office of Energy Research (now the Office of Science). Now, fusion simulation codes are being prepared for use on future exascale supercomputers (expected to become available within the next few years), capable of at least a billion billion calculations per second. In the context of the DOE Exascale Computing Project, efforts are under way to create a high-fidelity whole-device model of a magnetically confined fusion plasma. The long-term goal is to reproduce essential aspects of fusion experiments on a supercomputer, guiding the interpretation of existing experiments and helping to optimize the design of future devices, including, in particular, a pilot plant. To this end, many physical processes, involving a wide range of space and time scales, would need to be described in a way that accounts for their mutual interactions. Fusion research shares this challenge with many other scientific domains, from materials research to weather prediction, and contributes significantly to the development of a predictive computational science, with broad applicability.
The prospect of high magnetic field strengths of 20 Tesla and above drive the development, including private-sector ventures, of magnet coils manufactured from HTS. The technological leap to large HTS electromagnets now appears within reach, and their higher magnetic fields will enable more compact fusion machines than what is possible even when current niobium-titanium and Nb3Sn technologies have reached their practical performance limits. While plasma confinement in MFE systems is currently a major driver for HTS magnet development, high field electromagnets would be transformative in other fields as well, including particle accelerators for high-energy physics, magnetic resonance imaging for medical imaging and nuclear magnetic resonance (spectroscopic method used, for example, to determine the structure of organic compounds), all of which rely on high magnetic field strengths.
One technological area which will significantly influence the design of the pilot plant is advanced materials. Both fusion and fission applications require materials to sustain high heat and neutron flux. The ability to design and tailor material and component properties is now possible with material synthesis and characterization techniques. For instance, precision control of processes enables the creation of new alloys or nanostructured material to achieve desirable properties, such as high thermal conductivity or tritium retention. One example is the research and development on silicon carbide composites, which has produced an engineered material composed of silicon carbide fibers embedded in a silicon carbide matrix to form a strong fracture resistant material that is able to withstand high displacements per atom. These advanced materials will be critical to realizing efficient fusion and fission devices.
Low-Temperature Plasma Science
For the most part, laboratory plasmas for a wide variety of practical applications operate in a vastly different regime from those approaching the burning plasma state. Some naturally occurring plasmas can, along with technological plasmas, also be described as “low-temperature” plasmas, to contrast them with their much hotter magnetically confined cousins in fusion experiments. There is, however, an intersection between the two subdisciplines in the exhaust region of tokamaks and other magnetic confinement devices, known as the divertor. The divertor region of a fusion system is rich in low-temperature plasma physics, with a high-temperature plasma and a solid surface in close proximity. Understanding
and manipulating the interactions between the low-temperature plasma, neutral gas, and radiation in the divertor as a means of protecting reactor surfaces from the huge exhaust heat flux produced by burning plasmas will certainly lead to synergies with studies of low-temperature and technological plasmas. Neutral beam systems developed for heating of tokamak plasma, including ITER, are another area of overlap between the MFE and low-temperature plasma communities.
Robotics and Automation
A fusion reactor is perhaps the ultimate challenging environment for essential operation and maintenance, with the surrounding components characterized by high temperature, near 500 K, vacuum, liquid metals, confined spaces and kilograys (kGy) per hour neutron radiation. Remote maintenance will be a fusion power plant “device defining driver” whether the reactor is a large conventional aspect ratio design like the European Union DEMO or a high-performance design like the compact pilot plant. Remote maintenance concepts should be integral to the design, construction, inspection, maintenance, operation and decommissioning of the power plant and included in assessing the costs of material and waste flow through the plant. The robotics solutions developed for fusion will have wide applicability in many other sectors, essentially anywhere that robotics solutions are required because person-entry is either impossible or highly undesirable. This includes the space sector, the petrochemical industry where there is high risk of explosion, and broader nuclear applications, especially in decommissioning fission reactors. Beyond the direct application of robots developed for fusion, there is also considerable synergy between the sensors and control systems of robotics developed for fusion and other sectors. As an example of this, the sensors and control systems developed for autonomous vehicles have been applied on the remote maintenance system in JET (Joint European Torus) in the European Union.
Burning plasma and natural plasma research are mutually beneficial. As fusion plasmas become hotter, they more closely approach the very low levels of collisionality characteristic of many astrophysical plasmas. The process of magnetic reconnection, where rearrangement of the magnetic field impulsively releases a burst of energy, occurs in both settings. Instabilities driven by relativistic electrons and super-thermal ions have similar underlying physics. Models that describe particle and energy transport by fluctuating electric and magnetic fields are applicable in both settings. Through systematic variations of parameters that cannot be controlled in natural settings, laboratory experiments advance understanding in both disciplines. An example of this synergy is the Max Planck/Princeton Center
on Plasma Physics, which is a collaborative study on processes in astrophysical and fusion plasmas.
Public awareness is a critical element in maintaining support for the fusion effort and associated expenditures, and for inspiring young students to consider pursuing careers in fusion energy. A systematic communication and education campaign to engage the public should be maintained and expanded, with leadership by the DOE in collaboration with the National Academies of Sciences, Engineering, and Medicine as well as professional societies such as APS, ANS, and the Institute for Electrical and Electronics Engineers. A solid basis for such an effort is already in place: For example, the DOE Office of Science maintains a website with tutorial materials and frequent press releases describing recent advances. The national labs have also been successful in promoting fusion energy research at their respective institutions.
Future outreach initiatives should emphasize that realizing fusion as an energy source is a united effort with contributions from many sectors across the country and through international collaborations, and from many disciplines, including supporting technologies, as well as contributions to other science and technology advances made possible by fusion research. Consideration should also be given to systematic inclusion of fusion in energy-related instructional materials used in schools across the nation.
This chapter describes an expanded organizational structure for the DOE/FES that implements a research program evolving toward a long-term plan for fusion energy and strengthens community participation in the burning plasma science, materials science, fusion nuclear science and technology, and the engineering sciences needed to realize an economical pathway to fusion electricity for the nation. The committee arrived at several conclusions:
Finding: The program management strategy for the coming decades would benefit from exploiting the benefits of U.S. ITER participation as a full partner, while advancing a coordinated domestic research program directed at elements of a fusion power system not addressed by ITER.
Finding: The recommended expansion in scope and interconnected programs within DOE/FES will necessitate reconsideration of management and planning to ensure coordination between programs and efficient progress.
Finding: Success in fusion energy and global leadership will require opportunities for the United States to maintain and expand its institutional knowledge in the design, construction, and successful operation of experimental facilities on a gradation of scales.
Finding: Community input in setting technical priorities (including initiation of new projects and facilities and sunsetting those no longer needed) is essential for a healthy fusion energy program because of the interrelated nature of fusion energy technologies. Ongoing community engagement will further serve to promote community unity and foster morale and retention of a creative and productive workforce.
Finding: Opportunities exist to encourage and support private investment in fusion energy development and the focused, goal-oriented approach from U.S. industry, which is beneficial to fusion energy development.
Finding: Science and engineering resulting from U.S. investment in fusion energy research will have synergies and benefits to other disciplines. Specific examples include: exascale computing, high-field magnets employing HTS, robotics, high-performance materials, low-temperature plasmas and astrophysical plasmas.
Based on these findings, the committee makes the following recommendations:
Recommendation: The committee recommends a new division within the U.S. DOE Office of Fusion Energy Sciences to manage and organize research developing technologies needed to improve and fully enable the fusion power system.
Recommendations: The U.S. DOE Office of Fusion Energy Sciences should establish a formal strategic planning process by which, at regular intervals, respected scientific and technical leaders review progress on short- and long-term goals. This should include consideration of upgrades to and new U.S.-based research facilities needed to advance science and technology in support of fusion energy. Community input should be an essential element of this process.
Recommendation: The U.S. DOE Office of Fusion Energy Sciences (FES) should establish formal structures for regular communication with and among leaders of the research communities across the DOE/FES program.
Based on the committee’s observations of other programmatic ways to strengthen fusion research, the committee makes these additional recommendations:
Recommendation: It is recommended that the U.S. DOE Fusion Safety Standards be reviewed for consistency with current regulations, and updated to incorporate the community’s increased knowledge of the performance of fusion systems and current fusion program needs. In parallel with the fusion pilot plant design effort, a licensing strategy should be developed that includes transition from DOE to the Nuclear Regulatory Commission regulatory authority to ultimately allow for commercialization of fusion power.
Recommendation: In addition to continued participation in ITER, the U.S. government should explore partnerships with other existing and future facilities in Europe, Asia, and the United States as a means of pooling expertise and resources in advancing specific aspects of fusion science and technology, including aspects of the tritium fuel cycle and the accompanying areas of fusion nuclear materials, plasma-facing materials, fusion nuclear science, and enabling technologies.
Recommendation: The U.S. DOE Office of Fusion Energy Sciences should define mechanisms to manage assignment of intellectual property as a means to encourage both private and publicly funded researchers to establish mutually beneficial partnerships.
Recommendation: The U.S. DOE Office of Fusion Energy Sciences should conduct outreach initiatives that engage the fusion research community and inform the nation that the realization of fusion an energy source is a united effort involving many disciplines, including advanced technologies, and contributes broadly to national science and technology goals. Public awareness is a critical element in maintaining support for the fusion effort and associated expenditures, and for inspiring young students to consider pursuing careers in fusion energy and the fusion research community.
1. U.S. Department of Energy (DOE), 2018, Transformative Enabling Capabilities for Efficient Advance Toward Fusion Energy, Fusion Energy Sciences Advisory Committee, Washington, DC, February, https://science.energy.gov/~/media/fes/fesac/pdf/2018/TEC_Report_1Feb20181.pdf.
3. See the U.S. Magnetic Fusion Research Strategic Directions website at https://sites.google.com/site/usmfrstrategicdirections/home.
4. A. Bader, C. Chrystal, S. Diem, W. Guttenfelder, D. Hatch, C. Holland, N. Howard, et al., 2018, “Perspective on Magnetic Fusion Energy Directions from Early Career Fusion Scientists,” white paper submitted to the committee.
5. DOE, 1996, Safety of Magnetic Fusion Facilities: Requirements, DOE-STD-6002, Washington, DC.
6. DOE, 1996, Safety of Magnetic Fusion Facilities: Guidance, DOE-STD-6003, Washington, DC.
7. DOE, 1999, Supplementary Guidance and Design Experience for this Fusion Safety Standards DOE-STD-6002-96 and DOE-STD-6003-96, DOE-STD-6004, Washington, DC.
8. 2001, Final Report of the ITER Engineering Design Activities (EDA).
9. NRC, 2004, Burning Plasma.
10. University Fusion Association (UFA), 2017, “Status of University-Based Magnetic Confinement Research,” white paper submitted to the committee.
11. NRC, 2004, Burning Plasma.
12. M. Greenwald, D. Hillis, A. Hubbard, J. Hughes, S. Kaye, R. Maingi, G. McKee, D. Thomas, M. Van Zeeland, and M. Walker, 2015, “Recommendations for ITER Experimental Operation, U.S. Team Formation and Participation,” U.S. Burning Plasma Organization, http://www.burningplasma.org.
13. DOE, 2017, Annual Report on the State of DOE National Laboratories, Washington, DC, January, Figure 2-2.
15. M.W. Binderbauer, H.Y. Guo, M. Tuszewski, S. Putvinski, L. Sevier, D. Barnes, N. Rostoker, et al. (the TAE Team), 2010, Dynamic formation of a hot field reversed configuration with improved confinement by supersonic merging of two colliding high-β compact toroids, Physical Review Letters 105:045003.
16. M. Tuszewski, A. Smirnov, M.C. Thompson, S. Korepanov, T. Akhmetov, A. Ivanov, R. Voskoboynikov, et al. (the TAE Team), 2012, Field reversed configuration confinement enhancement through edge biasing and neutral beam injection, Physical Review Letters 108:255008.
18. DOE, 2015, Applications of Fusion Energy Sciences Research: Scientific Discoveries and New Technologies Beyond Fusion, Fusion Energy Sciences Advisory Committee, Office of Science, Washington, DC.