Conferences and Symposia

Abstract

On 23-27 March 1981, an IAEA Technical Committee and Workshop was convened in Erice to critically assess the so-called alternative fusion concepts. There were 38 participants from 12 countries at the Meeting, which partly coincided in time with the 5th Course of the Erice International School of Fusion Reactor Technology, dedicated to "Unconventional Approaches to Fusion". This made it possible for the participants of the Course to attend the IAEA Workshop and contribute to the discussions. As was suggested by the International Fusion Research Council, the Workshop concentrated on five alternative lines of approach to fusion: Stellarator, Reversed-Field Pinch, Bumpy Torus, Open-Confinement Configurations, and the broad class of experiments presently grouped under the name of Compact Toroids. At the general sessions, each concept was introduced through an overview of its state-of-the-art and a number of contributed papers, whereupon the individual subgroups met to discuss critical issues and then to consider and revise the Summaries prepared by the respective group chairmen. The five chairmen (listed here alphabetically, as are their summaries in Section 2) were L. Berry (ORNL) — Bumpy Torus, H.A.B. Bodin (Culham) Reversed-Field Pinch (RFP), C.W. Hartman (LLNL) — Open-Confinement Configurations, R.K. Linford (LASL) Compact Toroids, and D. Pfirsch (Garching) — Stellarators. At an additional session (Miscellanea) chaired by H. Obayashi (IPP, Nagoya), a number of contributions on high-density Z-pinches, plasma focus, screw pinches, etc. were presented and discussed; however, given the state of the art of these concepts, no attempt was made to critically assess them on a similar basis as the other five systems. (The interested reader is referred to the Proceedings of the 5th Erice School on Fusion Reactor Technology, where these papers will appear along with other contributions on the same subjects.) In addition to the five Summaries, this report includes an Appendix consisting of Tables I—V which show, for each concept, the parameters that best represent the achieved results, or the data expected for future devices, and the extrapolations to reactor requirements. Serious questions of physics, technology and economics of controlled fusion as a practical energy source have yet to be resolved. This involves exploring the full capability of the present plasma confinement systems and developing new ones. Within the existing framework of the international fusion programme, one approach which is most vigorously pursued is the tokamak. It has reached the combination of plasma parameters nearest to breakeven for fusion. Nevertheless, a tokamak reactor as presently conceived presents rather difficult technological and economic problems. Therefore, a large number of alternative concepts is actively studied, in order that the issues that bar the path to fusion power might be resolved. Among them the stellarator, the bumpy torus, the endplugged-mirror and the reversed-field pinch concepts (some existing in a number of distinct variations and magnetic geometries) have reached a development stage, in the understanding and the plasma parameters, that encourages tests of their future potential in experiments of a level comparable to what has been PLT for the tokamak line. The compact toroid concept represents a broad variety of experiments, aiming at much simpler reactor structures. They seem quite promising, but their development is one stage behind the previous group. In fact, even if many among them have already been explored in the past, only recently a new effort, justified by a better understanding of many physics issues, has been supported. Although these alternative concepts seem to offer specific reactor advantages relative to the tokamak, it is clear that