Fusion gain is the ratio of fusion power generated to heating power.

Super-H Mode works by increasing temperature and pressure in the outer region of the plasma, called the pedestal. The experiments showed – as the theory predicted – that proper tuning of the plasma cross-sectional shape and density leads to pedestal temperatures and pressures that are more than twice as high as those of typical pedestals.

Because plasma conditions in the core – where fusion takes place – are dependent on conditions at the edge, Super-H Mode enables as much as a four-fold increase in fusion performance.