Measurements of magnetic field fluctuations in the OHTE toroidal pinch

Both external and internal magnetic probes have been used in low‐current discharges and external probes in high‐current discharges to study the magnetic field configuration and its fluctuations in the OHTE toroidal pinch with toroidal field reversal. The equilibrium magnetic field configuration is close to that of the Taylor state in the central half of the plasma (μ≡μ0 b J/B is constant) but differs in the outer half (μ gradually goes to zero at the plasma edge). Measurements of the magnetic fluctuations indicate that the dominant fluctuation mode observed is the resistive internal kink with m=1, n≂18. The measured relative level of magnetic field fluctuations scales as B̃/B∼S − 1 / 2, where S is the magnetic Reynolds number.