The scaling laws for fusion follow a power law for size and magnetic field (see https://physics.stackexchange.com/questions/175830/nuclear-fusion-scaling-with-r

The scaling laws for fusion follow a power law for size and magnetic field (see https://physics.stackexchange.com/questions/175830/nuclear-fusion-scaling-with-reactor-size https://physics.stackexchange.com/questions/175830/nuclear-f...), which allow for better break even for commercial applications for larger fusion reactors like ITER. All of the smaller fusion reactors proposed need to use high Tc superconducting wire to generator higher magnetic fields for smaller reactors.