I'm no expert, but the stellerator design makes confinement of the plasma much easier and energy-efficient. AIUI, the twists ensure that the particles making up

I'm no expert, but the stellerator design makes confinement of the plasma much easier and energy-efficient. AIUI, the twists ensure that the particles making up the plasma are evenly affected by the magnetic forces from the coils. Hopefully someone who knows what they're talking about will be along soon ...