Magnetic Fields with Precise Quasisymmetry for Plasma Confinement.

Area of Science:

• Physics
• Plasma Physics
• Fusion Energy

Background:

• Toroidal magnetic fields are crucial for confining plasma in fusion devices.
• Quasisymmetry is a specific magnetic field property that enhances particle confinement.
• Achieving high-precision quasisymmetry has been a significant challenge in magnetic confinement fusion.

Purpose of the Study:

• To demonstrate that quasisymmetry and quasihelical symmetry can be achieved with significantly higher precision than previously thought.
• To show that these symmetries can be maintained over a substantial volume within a toroidal magnetic field.
• To assess the potential for exceptional plasma and charged particle confinement.

Main Methods:

• Numerical simulations and magnetic field optimization techniques were employed.
• The study focused on toroidal magnetic field configurations, specifically exploring aspect ratio 6.
• Symmetry-breaking mode amplitudes were calculated and minimized.

Main Results:

• Both quasisymmetry and quasihelical symmetry were achieved to a much higher precision than previously attainable.
• These symmetries were realized over a significant volume of the toroidal field.
• Symmetry-breaking mode amplitudes were reduced to levels comparable to the Earth's geomagnetic field (∼50 μT).

Conclusions:

• The findings indicate that high-precision quasisymmetry is achievable in toroidal magnetic fields.
• This enhanced symmetry promises exceptional confinement properties for charged particles and plasma.
• The results have significant implications for the design of future magnetic confinement fusion devices.