Stewart C. Prager, the director of the Department of Energy’s Princeton Plasma Physics Laboratory and a professor of astrophysical sciences at Princeton University, here offers a fresh defense of continued substantial support for research on extracting usable energy from nuclear fusion.

His “Your Dot” contribution builds on a recent fusion post by Burton Richter, a Nobelist in physics and author of a valuable book on energy, and another from Robert L. Hirsch, who directed the country’s fusion energy program in the 1970s.