Magnetic fields with precise quasisymmetry for plasma confinement

Abstract

Quasisymmetry is an unusual symmetry that can be present in toroidal magnetic fields, enabling confinement of charged particles and plasma. Here it is shown that both quasi-axisymmetry and quasi-helical symmetry can be achieved to a much higher precision than previously thought over a significant volume, resulting in exceptional confinement. For a 1 Tesla mean field far from axisymmetry (vacuum rotational transform $>$ 0.4), symmetry-breaking mode amplitudes throughout a volume of aspect ratio 6 can be made as small as the typical $\sim 50$ $\mu$T geomagnetic field.

Version to appear in Physical Review Letters, including new Supplemental Material

References in corpus (3)

• Necessary and Sufficient Conditions for Quasisymmetry
• Energetic particle transport in optimized stellarators
• Stellarator optimization for good magnetic surfaces at the same time as quasisymmetry

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