Number 3 (Story #2), October 11, 1990 by Phillip F. Schewe and Ben Stein THE COMPACT IGNITION TOKAMAK ,the proposed next-generation fusion machine, would be the first device in which fusion reactions would become self-sustaining. The CIT plan, put forward by the Princeton Plasma Physics Laboratory (where earlier this year their TFTR tokamak achieved a record-high plasma temperature of 348 million K) would, if approved by the Department of Energy and by Congress, cost an estimated billion dollars and would be under construction over the period 1992-1998. But even this represents only the next of several steps. An even bigger demonstration machine, perhaps engaging international cooperation, will be needed before a practical commercial-power-generating plant using fusion reactions could be built. Some experts believe that such a plant might be feasible by the year 2040. (The New York Times, October 9, 1990; part of an occasional series of articles on "big-versus-small science.")