Radial structure of Alfven eigenmodes in the DIII-D tokamak through electron-cyclotron-emission measurements

The spatial structure of toroidal Alfven eigenmodes and reversed shear Alfven eigenmodes in DIII-D is obtained from electron-cyclotron-emission measurements. Peak measured temperature perturbations are of similar magnitude for both toroidal Alfven eigenmodes and reversed shear Alfven eigenmodes and found to be delta T-e/T-e approximate to 0.5%. Simultaneous measurements of density fluctuations using beam-emission spectroscopy indicate delta n(e)/n(e)approximate to 0.25%. Predictions of the measured temperature and density perturbation profiles as well as delta T-e/delta n(e) from the ideal magnetohydrodynamic code NOVA are in close agreement with experiment.