Burning Plasma Bringing a Star to Earth (2004) / Chapter Skim
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1 Next Steps for the Fusion Science Program
1 Next Steps for the Fusion Science Program
Pages 10-50
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From page 10... ...
fusion program includes substantial efforts in inertial fusion energy. Considering these elements of the program was not part of the committee's charge.
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From page 11... ...
Thus, the terms "dominant heating source" and "half the energy input" are used interchangeably throughout the text to indicate the required alpha-particle heating contribution for a burning plasma experiment. 3National Research Council, An Assessment of the Department of Energy's Office of Fusion Energy Sciences Program, Fusion Science Assessment Committee (FUSAC)
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From page 12... ...
fusion program participate in a burning plasma experiment.4 During the past decade, the fusion community has achieved notable advances in understanding and predicting plasma performance -- particularly in comparing the results of theoretical and numerical calculations with the results of experi ments on small and intermediate physics experiments. These advances are docu mented in detail in the FUSAC report, which noted the "remarkable strides" in fusion science research.
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Undertaking a burning plasma experiment within the U.S. fusion program is a great challenge to the fusion community and to the program itself.
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PREPARING FOR A BURNING PLASMA EXPERIMENT Although developing any energy source is a long and difficult task, the interna tional fusion community has concluded that the critical next step toward fusion energy is to build a facility capable of achieving a burning plasma.6 Demonstrating a burning plasma is the experiment necessary for continuing to develop the scien tific and technological understanding to proceed toward the development of con trolled fusion energy. A number of experiments, ranging from a reactor-scale device using super conducting magnets, to compact, high-field copper-magnet devices, have been considered for implementing a burning plasma experiment (see Appendix C for a discussion of the three currently proposed burning plasma projects -- ITER, FIRE, and IGNITOR)
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The U.S. fusion community has asserted that a burning plasma experiment is an essential milestone on the road to practical fusion energy and has identified its
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From page 16... ...
In addition to enabling the next steps in research on plasma confinement and heating, a burning plasma experiment will present new scientific challenges with a plasma that is mainly self-heated by fusion reac tion products. The nonlinear behavior of magnetically confined plasmas at high temperature and pressure, a behavior that in turn may be modified by the alpha particle heating, is of fundamental interest.
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From page 17... ...
, · Fusion-plasma turbulence and turbulent transport, · Stability limits to plasma pressure, · Control of a sustained burning plasma, and · Power and particle exhaust. In addition to its scientific importance to fusion energy science, a burning plasma experiment may also make contributions to plasma science and science in general.
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From page 18... ...
In addition, by operating safely, reliably, and within the structural code requirements used by the nuclear industry, a burning plasma ex periment can demonstrate some of the favorable safety characteristics of fusion power. A burning plasma experiment could provide the opportunity to test and evalu ate blanket designs -- the blanket being the physical system surrounding the hot plasma; it provides shielding and absorbs fast neutrons, converts the energy into heat, and produces tritium.
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From page 19... ...
In summary, a burning plasma experiment would be of technological interest particularly with regard to the following issues: · Breeding blanket development, · Tritium processing, · Magnet technology, · High-heat-flux component development, and · Remote handling technology. Readiness to Pursue a Burning Plasma Experiment Having asserted the scientific and technical interest in a burning plasma experiment, it is prudent to ask if the fusion community is ready to undertake such an experiment.
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From page 20... ...
Burning plasma experiments are designed to handle safely abnormal events such as disruptions, should they occur. While there is confidence that these and other abnormal events can be avoided or mitigated, further research is needed to develop operating regimes that present less stringent heat loads to plasma-facing components.
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participation in ITER and a strong domestic fusion science program, must be maintained, recogniz ing that this will eventually require a substantial augmentation in fusion program funding in addition to the direct financial commitment to ITER construction [see Appendix E, p. 157, in this report]
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Critical science needs to be done in the U.S., in parallel with ITER, to strengthen our competitive position in fusion technology.9 The preparation for and execution of a burning plasma experiment will be a multidecade activity. The scientific and technological payoff from this experiment will be greatly enhanced by a domestic fusion research program that both supports and complements the ITER program effort, to progress toward the long-term fusion energy goal.
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From page 23... ...
Even on a success-oriented schedule, experiments on ITER will not begin for approximately 10 years. It is natural to ask, therefore, how the DOE fusion program should be designed, recognizing both this timescale and the importance of balancing the pursuit of the critical issues of fusion science needed to establish the basis for fusion energy.
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The fusion research portfolio addresses issues of importance to developing the knowledge base for fusion energy. It involves studies of plasma properties across a range of different magnetic configurations to test basic understanding of magneti cally confined plasmas, to improve reactor concepts, and to establish the science base that underlies the large-tokamak and burning plasma experimental programs.
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fusion energy program on a par with the goal of developing fusion energy technology" as the appropriate approach to fusion energy.14 This committee reaffirms these findings as guiding principles while embarking on a burning plasma experiment. It is clear that the commitment to move to a burning plasma experiment will require a substantial reconfiguration of the distribution of activities among the major elements of the domestic U.S.
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The third element of the program en compasses participation in international burning plasma experiments, an ele ment that was considerably deemphasized upon the withdrawal of the United States in 1998 from the original ITER program. The first two elements include most current research activities on non-burning-plasma issues -- such as plasma stability, nonlinear turbulence, self-organizing systems, magnetic field symmetry, and plasma sustainability at high pressure -- by studying plasma behavior across a portfolio of advanced tokamak and non-tokamak confinement considerations.
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Increasing the plasma pressure that can be confined stably is key to developing more attractive fusion energy. Con sequently, all of the research on magnetic configurations seeks to increase the maximum stable pressure limit.
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These issues are addressed below, followed by a discussion about the workforce and education issues that face the fusion program and the fusion community. Research Opportunities and Science and Technology Goals for the Next Decade: Direct Support of the Burning Plasma Program on ITER The preparation for and execution of a burning plasma experiment will be a multidecade activity.
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The committee believes that these activities will be a significant part of the domestic program -- in coordination with the international partners -- to support and prepare for the operation of a burning plasma experiment. These activities define a substantial part of the role that tokamaks can play -- with associated theory, diagnostic, and technology development -- as ITER is constructed and operates.
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The ST may also provide a reduced-cost path to the development of fusion energy.
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In addition to developing those technologies related to the burning plasma program, the domestic fusion program, in collaboration with international partners, must advance the knowledge base for fusion energy by addressing issues in three main areas: plasma technologies in support of advanced fusion science experiments, plasma chamber technologies, and fusion materials. Regardless of the de
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fusion program goals and interna tional fusion activities -- must be determined by the usual federal government process, advised by the fusion community, as described later in this report. Theory, Simulation, and Computation Transferring knowledge of burning plasmas to other elements of the fusion program will require a detailed theoretical understanding of the fundamental physical processes involved.
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The ramp-up to a burning plasma experiment poses special challenges in meeting workforce needs, particularly in light of the workforce demographics in fusion and plasma science and engineering. Extending beyond the needs of the burning plasma experiment is a pressing need to replace aging personnel in fusion and plasma sciences in the universities and the national laboratories.16 In comparison with other fields, university fusion and plasma sciences faculty members are older than their counterparts, with comparatively fewer new hires in the field.17 The situation is similarly critical at the nation's three largest fusion science laboratories, where there is a significant bulge in the scientific workforce in the 50- to 60-year-old age group.18 Meeting these personnel needs is a key function of the university fusion programs.
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From page 34... ...
This isolation has many detrimental effects, including reduced appreciation for fusion science, decreased support for faculty appointments in fusion science, and reduced access to the broad popula tion of science and engineering students. The University Fusion Association's re cent survey of university plasma and fusion science programs shows a decline of fusion science positions in the most highly ranked academic institutions in the United States.20 These programs tend to be the largest, most visible university fusion programs.
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While the specific projects to be pursued will change as the fusion program evolves, the important role of university research in the U.S. fusion program will continue throughout the era of the burning plasma experiment and beyond.
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fusion program should commit in order to gain sufficient benefit from this opportunity to study burning plasmas. It said, "The United States should pursue an appropriate level of involvement in ITER, which at a minimum would guarantee access to all data from ITER, the right to propose and carry out experiments, and a role in producing the high-technology components of the facility, consistent with the size of the U.S.
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From page 37... ...
Because a burning plasma experiment is a key step on the necessary scientific critical path toward fusion energy, any delays in realizing such an experiment -- such as failure in the ITER negotiations -- will necessarily delay the domestic program's ability to address and under
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From page 38... ...
fusion program and beyond. It can be expected that a burning plasma experiment will make critical contri butions to understanding fusion science and fusion technology issues such as the following: behavior in a self-sustained burning plasma burn, fusion-plasma turbu lence and turbulent transport, stability limits to plasma pressure, control of a sustained burning plasma, power and particle exhaust challenges, breeding blan ket development, tritium processing, magnet technology, high-heat-flux compo nent development, and remote handling technology.
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fusion program structure. Finally, the program requires a fusion technology component whose scale is commensurate with the level of commitment and the timing required to achieve the fusion energy goal.
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fusion program, that the community consider changes in the way that it operates in order to posi tion itself to provide the intellectual leadership of chosen areas of research and to optimize the return on its investment. The choice of major research thrusts will be determined by the government with significant input from the fusion community; examples might include ele ments of advanced tokamak development, stabilization of large-scale MHD insta bilities, turbulence and transport studies, and so on.
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The committee is concerned about the pressures on the U.S. fusion program as the United States moves into the ITER program if there is no increase in funding for the OFES.
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It is clear that, at a minimum, in order to capture the benefits of a burning plasma experiment, augmenting the U.S. fusion program to cover all of the U.S.
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fusion program that includes participation in the ITER program. Notwithstanding the success of the current portfolio approach to the U.S.
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CONCLUSIONS AND RECOMMENDATIONS -- ELEMENTS OF A STRATEGICALLY BALANCED FUSION PROGRAM Conclusions Conclusion: Participation in a burning plasma experiment is a critical miss ing element in the U.S. fusion science program.
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fusion program, it is essential to analyze the program as a unified, science-driven effort in pursuit of the fusion energy goal and composed of complementary and diverse efforts. All three ele
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From page 46... ...
For instance, it is clear that a technology program without a strong science base, or a science program without a strong technology base, will leave the United States unable to build effectively on the developments coming from more advanced programs abroad as well as from ITER. Although not directly related to a burning plasma experiment in a tokamak, some scientific issues of importance to the long-range development of the U.S.
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From page 47... ...
Nevertheless, the role that university programs play in meeting personnel needs and providing new ideas and training opportunities can be expected to continue, throughout the era of the burning plasma experiment and farther along the path to practical fusion energy. Recommendations for a Program Strategy The committee offers its conclusions as guiding principles for the Department of Energy as it plans to maintain a strategically balanced fusion program in support of the ITER project, aimed at maximizing the scientific and technical understanding and providing the foundation of fusion as an energy source.
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From page 48... ...
fusion program should be developed that includes U.S. participation in ITER, a strong domestic fusion science and technology portfolio, an integrated theory and simulation program, and support for plasma science.
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From page 49... ...
The prioritization process should be organized with three elements of the fusion program in mind: -- To advance plasma science in pursuit of national science and technol ogy goals; -- To develop fusion science, technology, and plasma confinement inno vations as the central theme of the domestic program; and -- To pursue fusion energy science and technology as a partner in the international effort. These program elements are indeed the three goals of the U.S.
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From page 50... ...
50 B U R N I N GP L A S M A FINAL COMMENT The committee concludes that the United States is ready to take the next critical step in fusion research and recommends that participation in a burning plasma experiment be implemented through participation in the ITER project as part of a strategically balanced fusion program. As the following chapters show, the oppor tunity for advancing the science of fusion energy has never been greater or more compelling, and the fusion community has never been so ready to take this step.
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