Turbulent transport in the Madison Symmetric Torus reversed-field pinch

Abstract

Measurements of edge turbulence and the associated transport are ongoing in the Madison Symmetric Torus (MST) reversed-field pinch [Fusion Technol. 19, 131 (1991)] using magnetic and electrostatic probes. Magnetic fluctuations are dominated by m=1 and n ∼2R/a, tearing modes. Particle losses induced by magnetic field fluctuations have been found to be ambipolar (〈J̃∥ B̃r〉/B0=0). Electrostatic fluctuations are broadband and turbulent, with mode widths Δm∼3–7 and Δn∼70–150. Particle, parallel current, and energy transport arising from coherent motion with the fluctuating Ẽ×B drift have been measured. Particle transport via this channel is comparable to the total particle loss from MST. Energy transport (from 〈P̃Ẽφ 〉/B0) due to electrostatic fluctuations is relatively small, and parallel current transport (from 〈J̃∥ Ẽφ〉/B0) may be small as well.