The Path to Fusion Energy for Concepts Currently at the Concept Exploration Level
Concept Exploration (CE) experiments within the Innovative Confinement Concept Program have a unique role which impacts their contributions to the development of fusion energy. As stated in the FESAC ''Report on Alternate Concepts:'' These [CE] programs are aimed at innovation and basic understanding of relevant scientific phenomena. The emphasis on innovation motivates their application to the search for a better fusion reactor configuration. In addition, because of their unique character the CE experiments offer excellent opportunities to couple fusion-plasma physics to other sciences. A recent example of coupling is the fusion self-organized plasmas to reconnection physics and extra-terrestrial plasmas. Perhaps of even greater importance is the education of the future scientists needed for developing fusion energy. The CE experiments, both at universities and national labs, are of a size students can ''get their hands around;'' young scientists and engineers will be attracted by this intellectual challenge combined with the vision of low-pollution energy for mankind represented by a burning-plasma experiment. A CE concept showing promise for fusion energy is expected to advance to the Proof-of-Principal stage. Experience has shown that this progression may occur in several ways: NSTX followed from success in START, a CE-level experiment in England; NCSX built on a broad base of theory and a strong international stellarator data base, without a CE experiment to test quasi-axisymmetry; and MST is following an upgrade path from the CE experiment of the same name. The lesson to be learned is a highly positive one, namely that the portfolio approach--with its five stages of development--is being applied in a flexible and pragmatic manner without artificial constraints from strategic planning. This lesson also makes it clear that as we move towards the development of fusion energy we need to determine the best way forward for each promising configuration, taking advantage of its unique attributes. The reactor embodiment of a CE concept may look much like an improved tokamak or may, in some visions, be very different. This may result in more complex decision points or in zig-zags in progress towards the energy application as the science behind the concept becomes better understood. The resulting innovations may shorten the time to fusion energy; alternatively, maturation of the development path may cause the reactor embodiment of the concept to follow (in time) testing of a tokamak reactor. The long-term success of fusion energy requires us to be flexible in our plans, while recognizing that issues of handling large powers and energy, mitigating neutron damage, and many other practical matters cannot be delayed for the discovery of the ''best'' reactor configuration. Finally, most CE concepts involve more complex physics than the tokamak. This places them at a significant disadvantage for rapid deployment: Because their budgets are low, it is difficult to develop sufficiently the scientific knowledge needed to justify an experiment at the PoP stage. Success in moving to this level will need the use of sophisticated diagnostics to generate the data needed to guide and demonstrate understanding, coupled (in many cases) to advanced computational modeling of the complex phenomena. These are both relatively expensive undertakings, suggesting that progress forward may often be more of a continuous process with small steps than a discontinuous jump from the CE to the PoP level. MST is an example of such a progression. Innovative use of advanced diagnostics, perhaps on more than one experiment but certainly drawing on collaborations among researchers, may prove to be cost effective. Plans for advanced modeling, such as that by the ongoing ISFOS Panel to develop a roadmap for a Fusion Simulation Project, need to explicitly recognize the needs of the ICCs in general and the CEs in particular.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 15002742
- Report Number(s):
- UCRL-ID-151320; TRN: US200418%%79
- Resource Relation:
- Other Information: PBD: 9 Jan 2003
- Country of Publication:
- United States
- Language:
- English
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