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.
The DIII-D plasmas in Super H Mode experiments, if converted to DT fuel, would produce more than 4 million watts of fusion power. This corresponds to a fusion gain, the ratio of fusion power produced to heating power injected, of about ½, the highest ever achieved on DIII-D or other tokamaks of similar size.