Large magnets: Where we are, and where we must go

There is a great deal of interest in magnet technology at this particular time. There are major projects in construction and serious plans for very significant scale-ups; it is therefore of particularvalue at this time to examine the process of scale-up. For example, some of the future magnets being considered by the MHD and Fusion Communities seem very large and ambitions relative to our present level of accomplishment, and this has given rise to a degree of uncertainty, and a continuing reevaluation of how to get from here to there. The question is generally posed in terms of what is the current data base relative to what is required before the next step can be taken. Both the allowable level o.f risk, and the preceived risk are always part of the consideration. It is difficult, if not impossible, to quantify the actual risk, and therefore the size of the allowable steps to be taken is always arguable. Before looking ahead to assess the future risks, it might be instructive to examine the current construction projects in several different programs, and to speculate on the data base available when these projects were authorized. This will at least allow us to assess tne degree of past risk which we have been willing to accept. It will also allow us to explore the type of supportive R&D .and quality assurance programs that ;:hese <"'trrent projects have viewed as important.