Measurement of Internal Magnetic Field Fluctuations in a Reversed-Field Pinch by Faraday Rotation

W. X. Ding, D. L. Brower, S. D. Terry, D. Craig, S. C. Prager, J. S. Sarff, and J. C. Wright

Phys. Rev. Lett. 90, 035002 – Published 21 January 2003

Abstract

Magnetic field fluctuations (and the associated current perturbation) have been measured in the core of a high-temperature reversed-field pinch using a newly developed fast-polarimetry system. Radial magnetic field fluctuation levels of $\sim 1 %$ are measured in standard-reversed-field pinch discharges which increase to $\sim 4 %$ during the sawtooth crash (enhanced dynamo). The fluctuation level is reduced fourfold for high-confinement plasmas where the core-resonant tearing modes are suppressed.