Fusion: Promise, Progress, and Problems

This paper is based upon an invited talk in which the author was asked to express his opinions on the promise, progress and problems in fusion energy research. The first observation was that, to an outsider, all D-T burning, solid first wall, fusion reactors look more or less the same. In reality all the approaches have much in common. Consequently, choosing between them involves a need for a deep understanding of the significance of their apparent virtues e.g., high gain, good confinement, high beta, low recirculating power, high thermal-electric conversion efficiency, maintainability, etcetera; and ditto for other fuel cycles and liquid wall systems. Finally, while substantial progress has been made across the board, it is premature in either inertial or magnetic fusion to choose between options that appear to have the capability to access a physics, technology, and engineering box that might include a viable reactor.