Tokamaks do fuse a lot of atoms, just not yet enough to get more energy out than they put in. The record so far is energy output at 70% of the energy input. Th

Tokamaks do fuse a lot of atoms, just not yet enough to get more energy out than they put in. The record so far is energy output at 70% of the energy input. The output scales with the square of plasma volume and fourth power of magnetic field strength, which is why net power is expected from ITER (which is huge) and SPARC (which uses new superconductors for especially powerful magnetic fields).