Fusion energy is suddenly flush with cash. Troy Carter knows that won’t be enough

The plasma physicist Troy Carter leads the U.S. fusion energy program at Oak Ridge National Laboratory. It’s one of science’s hottest and most humbling pursuits: trying to understand plasma, the superheated, electrically charged gas at the heart of stars—and, since the 1950s, every hydrogen bomb test and fusion experiment. Unlike the fission reactions that power the world’s 440 existing reactors, fusion promises relatively safer, zero-carbon power, with far less radioactive waste. For decades...