An Assessment of the Department of Energy's Office of Fusion Energy Sciences Program (2001) / Chapter Skim
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Interactions of the Fusion Program with Allied Areas of Science and Technology
Interactions of the Fusion Program with Allied Areas of Science and Technology
Pages 62-82
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From page 62... ...
In reality, high-temperature plasmas are not only of great intrinsic scientific interest but also of great general interest in fields from astrophysics to material science, with the goal of basic plasma physics being to elucidate the linear and nonlinear properties of the plasma medium under the wide variety of conditions in which it is encountered in nature and in the laboratory. The fusion program should be credited with having played a major role in advancing our experimental and theoretical understanding of this "fourth state of matter." Many of the fundamental concepts of fusion science, ranging from linear stability theory to kinetic theory and nonlinear dynamics, as well as its experimental techniques, have close connections to other areas of physics.
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From page 63... ...
Fusion science aims to study the stability properties and transport behavior of such systems, and in order to conduct these studies, it has made progress in a number of topical areas that have had a broad impact on the larger scientific and industrial community. Examples of some cross-cutting research topics are stability theory; stochasticity, chaos, and nonlinear dynamics; dissipation of magnetic fields; origins of magnetic fields; wave dynamics; and turbulent transport.
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From page 64... ...
Understanding how waves propagate and are absorbed in nearly collisionless plasma was a key scientific goal for the fusion program and has had an important impact on understanding phenomena in space plasma physics. Building on Landau's idea of the wave-particle resonance as a mechanism for collisionless dissipation, fusion scientists developed models to describe the absorption of high-power radio-frequency waves from kilohertz to multigigahertz and benchmarked the predictions in fusion experiments.
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From page 65... ...
The U.S. fusion program has advanced the world effort in a number of key scientific areas: In the late 1950s, the basic energy principle for MHD stability was largely derived in the United States, particularly using the powerful Lagrangian variational dW approach.
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From page 66... ...
In many areas, the richness of new research areas relates to the deep connections between plasma physics and other physical science disciplines and complements work done purely in the fusion domain. Promising interdisciplinary research areas include the following: · Nonneutral plasmas.
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From page 67... ...
plasma research is its connection with astrophysics as fusion experiments directly relevant to important astrophysics problems become more sophisticated and as theory and simulations capable of connecting experiments to astrophysical observations become more sophisticated. The principal areas of interest are the origins of magnetic fields (the dynamo problem)
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From page 68... ...
shows the highly filamented state of the remnant's gaseous interior that is the result of synchrotron radiation from energetic electrons spiraling in the magnetic field of the remnant. The Chandra X-ray Observatory image of the Crab Nebula (bottom right)
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From page 69... ...
The radio polarization fraction and E-vector direction are shown in the bottom panel. Clearly, major events are taking place 11 arcsec west of the quasar, where the radio jets bend, the x-ray emission drops, and the radio emission becomes unpolarized, followed by realignment of the magnetic field direction.
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From page 70... ...
70 AN ASSESSMENT OF THE DEPARTMENT OF ENERGY'S OFFICE OF FUSION ENERGY SCIENCES PROGRAM FIGURE 4.3 This solar image was taken with the TRACE telescope, using a normal incidence soft x-ray mirror whose band pass is centered on an emission line of Fe IX; the image clearly shows the highly complex structuring caused by solar surface magnetic fields and the remarkable "plasma loops," which indicate million-degree solar gases trapped by these magnetic fields. Courtesy of NASA and the Stanford-Lockheed Institute for Space Research.
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From page 71... ...
DOES THE FIELD MAINTAIN LEADERSHIP IN KEY SUPPORTING RESEARCH AREAS? Quite aside from spawning new ideas that gain currency in other allied fields of physics, fusion research also involves the use and development of tools that it shares with other physical science disciplines.
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From page 72... ...
Here, the committee briefly discusses two of the grand challenge topics, turbulence and macroscale dynamics, commenting on the computational techniques employed and areas where greater resources or more effort is required. Scientists studying transport have developed novel magnetic-flux-tube-based coordinate systems for dealing with the extreme anisotropies in the turbulence that develops along and across the magnetic fields confining the hot plasma.
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From page 73... ...
However, the DOE DP laboratories are in the process of procuring even more powerful machines, which will not be accessible to fusion researchers. To develop the predictive capability required for performance predictions in present and future machines, the fusion program will need to keep pace with advances in computational power.
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From page 74... ...
In recent years, these links have developed in the context of problems without any obvious direct application to fusion energy science, so they fall into the category of work on general plasma physics, which has been relatively poorly supported by the DOE fusion program. The funding for the NSF/DOE program in plasma science, now in its fourth year, supports research in basic plasma science and is a positive development.
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From page 75... ...
Production Techniques Using tools developed in the fusion program, plasmas can be produced with temperatures from 104 to 108 K and densities from about 109 to 10~5 particles/cm3. Moreover, techniques have been developed to adjust the spatial structure of the plasma the magnetic field, the plasma temperature, and density profiles.
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From page 76... ...
Through a charge exchange interaction between the beam atoms and impurity ions, the impurity ion emission is enhanced, providing a spatially localized diagnosis of impurity ions. The Stark splitting of emission lines from the neutral atoms (produced by the motional electric field experienced by the atoms moving through the magnetic field)
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From page 77... ...
Admittedly, the survey could have been usefully expanded to include more universities and departments, since plasma scientists are also to be found in astrophysics, applied mathematics, and various engineering departments. The disturbing result from this survey is, however, that at these 25 universities, out of roughly 1300 physics faculty, there are only three assistant professors in plasma physics, well below the level at which the plasma physics faculty at these institutions can be sustained.
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From page 78... ...
No single scientist or small group of practicing scientists has the breadth of knowledge required to tackle such large and complex problems. In the area of theory and computation, the absence of closely interacting teams of critical mass is inhibiting a concerted attack on a number of central science issues confronting the fusion research program.
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From page 79... ...
Because the topics listed above have such broad scientific applicability in allied fields, collaborations could be set up with scientists having expertise of great value to the plasma science and fusion research effort. An explicit goal of the centers should be to convey important scientific results to both the fusion community and the broader scientific community.
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From page 80... ...
To ensure that increasing institutional diversity is a continuing goal, the committee recommends that the breadth and flexibility of participation in the fusion energy science program should be a program metric. Several new centers, selected through a competitive peer-review process and devoted to exploring the frontiers of fusion science, are needed for both scientific and institutional reasons.
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From page 81... ...
The workshops would aim to bring in new ideas and collaborators as well as to disseminate to other fields the results they are achieving as they address the fundamental problems of fusion science. Potential focus topics for centers include turbulence and transport, magnetic reconnection, energetic particle dynamics, and materials; other topics would emerge in a widely advertised proposal process.
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From page 82... ...
The mission of MULES, following the restructuring of the program in 1996, has been to establish the knowledge base in plasma physics required for fusion energy, with the result that a substantial number of plasma science issues are being explored within the fusion regime that also have applicability to allied fields such as astrophysics. For this reason, the committee believes that NSF should begin to play a larger role in the solution of these basic plasma science issues.
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