The scientific community is now in its seventh decade of magnetic fusion research. Great strides have been made since the first stellarators and pinches in the 1950's to the D-T experiments in TFTR and JET tokamaks in the 1990's. This community of scientists and engineers is now poised to build a device capable of significant levels of alpha particle self-heating, pursuing the long-held dream of a "burning" plasma. This would be a remarkable achievement, something which even the general public would identify as one of man's greatest scientific successes. It is a sad fact that within our own fusion community, it is not talked about as such. In part this stems from disappointed regarding the required device size. It seems that nature has conspired to ensure that the magnetic route to controlled fusion demands a device of considerable magnitude, of order 10 m in linear dimension, rather than a more convenient size of say 1 m. In defense of the community, one must bear in mind that these devices are meant to imitate something as large as a star and the fact that this appears to be possible in a device close to human scale is nevertheless a significant achievement.

The relatively large size of course means a high capital cost and high technical and financial risk, at least by the standard measures used in industry. It is for this reason that fusion development requires leadership by governments—entities which should act for the common good and are prepared to accept higher levels of risk. Mankind, through government leadership, has been building large and costly structures for millennia and there is no reason why fusion researchers or their sponsors should be intimidated by the designs presently on the table. It would be a great shame that if after more than 50 years of fusion research, when this community is reasonably sure how to build a burning plasma device, that we lose our nerve and determination.

While the raison d'être for magnetic fusion research has always been connected to the prospect for energy production, fusion research has and continues to be an engine for the pursuit of advance plasma science. Our advances on the science front have matched step by step our advances on the energy front. Science is the means to the energy goal. We are presently at a point in tokamak research where incremental advances in our science understanding are being made on existing devices, but where quantum leaps are not likely because of the lack of a new device with increased capabilities. Most major leaps in the science in the past have been linked to new and more powerful devices and this is likely to remain the case. In particular, there are many aspects of burning plasma physics that cannot be explored simply because the fusion community lacks a device with significant alpha particle self-heating. One of the key areas to be researched is the integration aspect of burning plasma science, e.g. high levels of self-heating with profiles compatible with current drive and reasonable margin from disruptive limits, power levels and plasma densities compatible with power and particle handling at the wall, etc. Integration can only be achieved in a new and more powerful tokamak.

At the present time, the US fusion community is considering what to do with respect to a number of burning plasma initiatives. Meanwhile, the European Community, Canada, Japan and Russia are negotiating on how to proceed with the International Thermonuclear Experimental Reactor (ITER). This project involved the US fusion community from its inception in 1985, through the conceptual (1988-1990) and engineering (1992-1998) design phases. The US withdrew from the project in 1998 after making a significant contribution to the project and spending approximately $400 million (as spent dollars). Over that period, R&D and design efforts and supporting experiments on existing tokamaks have produced a substantial body of knowledge, both with respect to technology and physics. The present ITER design has been externally reviewed a number of times and has been deemed credible. Several technical uncertainties remain regarding key plasma physics parameters, but success appears to lie with the range of these uncertainties. Nevertheless, such uncertainties mean that this project should be properly considered an "experiment" and not a proto-type commercial reactor. The present design is of sufficient detail that construction can start immediately. The US is morally and legally a part owner of this design.

There are numerous practical reasons why the US should rejoin ITER as soon as possible. As stated above, it is a credible design that is ready to go now! It is relatively cheap if pursued in collaboration with the other ITER partners, allowing the US and its partners to continue with essential base program elements. A US showing some resolve would embolden the other ITER partners, who themselves have fusion detractors. The sooner the US rejoins, the easier it will be for the US to influence important decisions about the design, the awarding of construction contracts, the project's structure and siting. The US will regain full access to the world-wide body of fusion science and technology.

There are two main concerns voiced amongst the US fusion community regarding a burning plasma initiative that must be considered. The first concern is related to the technical uncertainties in the ITER design. It has been suggested that our present knowledge of tokamak physics is incomplete and that continued research on present devices is needed before a major next-step should be taken. While it is certainly correct that our present knowledge of tokamak physics is still developing, this begs the question, how do we determine an appropriate threshold in our knowledge past which a next-step is warranted? There is clearly an optimal level of ignorance for making such a decision. Knowing too little means that the costly experiment is too risky, knowing too much means that it is no longer an experiment. This is a difficult decision and must be weighted by the performance uncertainty, the flexibility of the design to handle surprises and the nerve of the funding body. With respect to performance uncertainty, enormous efforts have been made over the last 10 years in estimating key physics elements (like energy confinement time, H-mode threshold power, etc) for ITER based on operating experience in present devices. Continued research on existing tokamaks is essential up to and during ITER operation, since it will increase our confidence on these and other fronts. Such devices are more flexible and can provide partial advance information regarding ITER issues. Of course it will take the operation of ITER to really discover where the surprises might lie. With respect to the ability to respond to surprises, since the US withdrew from ITER in 1998, the ITER design has been made more flexible, with increased shaping possibilities and other advanced tokamak features. Finally, while the nerve of the US funding body is difficult to assess, the level of risk appears to be acceptable to the traditionally conservative European and Japanese governments.

The second concern is related to the direction a burning plasma initiative would take the US fusion community. There are many who feel the tokamak is not a good candidate for the ultimate fusion reactor and are presently devising alternatives, e.g. stellarators, spherical tokamaks, FRC's, etc. While there are certainly concerns about the tokamak approach, particularly with respect to disruptions, steady-state operation and low power density, it is the best candidate at present to pursue burning plasma science. Nevertheless, it would be prudent for the fusion community to be looking down the road beyond the tokamak should it not be a total success in these problem areas. Thus, alternatives to the tokamak must be continued and even expanded upon. The tokamak should be viewed as a device that we can presently stand behind, one which can achieve a burning plasma and one where a whole host of physics and technologies common to all magnetic fusion concepts can be developed. One must remember that the construction of a magnetic confinement device is only a small fraction of the total effort required to give birth to a DT fusion site, with the majority of the investment tied up in the infrastructure, buildings, power supplies, tritium plant, cooling plants, nuclear handling, etc., not to mention the significant investment of time in simply negotiating an international site. The latter, by itself, would be a major achievement, something which even at this date eludes the international community. The alternates should take up the challenge to be ready in some decades to build a burning device, perhaps towards the end of ITER or beyond. If deemed sensible, in fact, it would be natural for this to occur as a natural extension of the ITER project at the international site, taking advantage of all of the above-stated site credits. To strive for that, alternates must have sustained funding.