Experimental evidence for a reduction in electron thermal diffusion due to trapped Particles

New high time resolution measurements of the electron thermal diffusion χ_e throughout the sawtooth cycle of the Madison Symmetric Torus reversed-field pinch have been made by utilizing the enhanced capabilities of the upgraded multipoint, multipulse Thomson scattering system. These measurements are compared to the χ_e due to magnetic diffusion predicted by using information from a new high spectral resolution zero-β nonlinear resistive magnetohydrodynamic simulation performed, for the first time, at the Lundquist number of high current Madison Symmetric Torus plasmas (S=4×106). Agreement between the measured and predicted values is found only if the reduction in thermal diffusion due to trapped particles is taken into account.