New Evidence of Relaxation in High-β Plasmas Driven by Rotating Magnetic Fields

New evidence of relaxation in high-β plasmas has appeared in the steady-state field reversed configuration sustained by rotating magnetic fields, as signified by the self-generation of a significant toroidal field, with spontaneous transition to a higher confinement state. Detailed internal magnetic measurements reveal that the transition occurs at the onset of low-frequency drift modes. The final relaxed state exhibits the following key properties: (1) a near-force-free state in the core region, (2) a large q ∼ 1 along with significant magnetic shear near the magnetic axis, and (3) significantly improved confinement.