A Vacuum Cleaner with Two Buttons: How Plasma in a Tokamak Gathers Particles Toward the Center on Its Own
A vacuum cleaner sucks in dust even if there is more of it near the nozzle. The same happens in a tokamak: plasma particles are drawn toward the center, even though their density is higher at the edge. This phenomenon is called particle pinch, and it contradicts the usual rule that everything tends to move from dense regions to sparse ones.