The role of the technology program has been to conduct basic scientific research into materials, component development, manufacturing processes, plasma materials interactions, heating and current drive methods, fueling techniques, magnet technology, neutron damage, failure modes, and repair methods. Advances in these areas have been a key factor in the improvement of fusion device performance. A more attractive fusion product includes higher power density, lower total plant cost, reduced radioactive waste or greater ability to recycle plant components, greater reliability, and easier maintenance of the plant. The technology program is conducting research is all of these areas.
The next generation of fusion devices presents major challenges in terms of component performance and reliability, fuel-handling systems including tritium technology, and maintenance concepts. Moreover, the choice of materials and design concepts for "in-vessel" components (e.g., divertor, first wall, blanket, shield, final optics and vacuum vessel) will more than anything else determine the safety and environmental characteristics of both magnetic and inertial fusion energy. Systems design activities, such as those carried out in the ARIES, Prometheus, and Sombrero studies are an important element of the Technology Program because they help to provide the essential framework to construct the overall strategy of the U.S. Program. The near-term emphasis is on developing better tools for the production and control of high-temperature MFE plasmas and, thus, the further development of plasma science. For IFE, research on chamber-target technologies is focused on key feasibility issues that bear on the high-pulse-rate application of candidate drivers for IFE. The longer-term emphasis is on resolving key feasibility issues for the development of fusion energy. These include extraction and utilization of heat from fusion reactions, breeding and handling of fuel (tritium) in a self-sufficient system, demonstration of remote maintenance systems and reliable operation, and realization of the safety and environmental potential of fusion energy. Incorporation of improved materials and technology concepts is a crucial element. The development of reduced-activation materials is particularly important to realize the environmental potential of fusion energy.
The Technology Program depends on, and has fostered, a highly integrated approach involving broad systems assessments, design studies on a wide variety of specific concepts, materials research and development, component engineering and development, and safety analysis. Such an integrated approach is essential to the successful development of the knowledge base for attractive fusion energy sources because of the complex nature of fusion systems and the multidisciplinary aspects of the underlying science and engineering.
Higher field strength superconducting Magnet Technology and radio frequency Heating and Current Drive systems operated in a manner to stabilize MHD activity and Plasma Facing Component technology aimed at facilitating edge transport barriers would be the three principal technology program elements directly applicable to increasing the fusion power density. Plasma heating systems can be used to generate gradients in the plasma flow velocity and pressure profiles that are conducive to reducing turbulence or generating internal transport barriers. Manipulating the plasma current density profile via non inductive RF current drive techniques has been shown to increase MHD stability margins and hence b in a wide variety of tokamak experiments. Peaked density profiles as produced from advanced plasma fueling systems have also been shown to dramatically reduce c to near neoclassical levels in the central plasma region leading to higher reactivity plasmas. Understanding of plasma materials interaction (PMI) and development of improved plasma facing components has been instrumental in achieving conditions in the plasma edge region that have led to the reduction in c associated with the H-mode. Net fusion power can be maximized not only by reducing the recirculating power fraction, hR , which implies superconducting magnet technology and more efficient heating and non inductive current drive systems, but also by extracting heat at higher temperature for improved thermodynamic efficiency. The latter is being addressed in the PFC, Fusion Technology, and Materials program elements (i.e., high temperature radiation resistant structural materials, thick flowing "liquid wall" heat extraction and tritium breeding concepts). Similarly innovative research in the Fusion Technology program aimed at developing thick liquid walls to absorb the bulk of the neutron energy may offer a promising solution to reduce in-vessel component and structural material failure rates (reduced component replacement costs and higher availability. Improved techniques for Remote Handling and Maintenance are also essential for fusion power systems in general and figure heavily in increasing availability. The Tritium System and Fusion Safety elements of the portfolio speak directly to the environmental attractiveness of fusion power in general and licensing issues of next step burning plasma devices in particular. Finally, a self-consistent integration of the technology and science program elements as embodied by reactor designs and projections of COE for the various magnetic confinement pathways takes place in the Systems Design element.
The purpose of this Key Question is to foster discussion aimed at identifying the opportunities for technology to improve the vision for an attractive and competitive fusion product. The subtopics for this common question are the key questions posed to the two subgroups in this area. Each subgroup is asked to identify the most important contribution(s) to improving the vision for fusion energy in the area represented by their key question. A roll up session where the answers from all of the key question discussion groups in both subgroups will be held to collect the identified opportunities. This roll up session would try to identify important contributions that can be accomplished in the next 10 years. The results would be presented at the general summary session at the end of the conference.