Fusion scientists have solved a long-standing mystery inside tokamaks, the donut-shaped machines designed to harness fusion energy. For years, experiments showed that escaping plasma particles hit one side of the exhaust system far more than the other, but simulations couldnโ€™t explain why. Now, researchers have discovered that the rotation of the plasma itself plays a crucial roleโ€”working together with sideways particle drift to create the imbalance.