Short wavelength fluctuations and electron heat conductivity in enhanced reversed shear plasmas

Short wavelength fluctuations with k ∼ ω_pe/c and kρ_i ∼ 5 are detected by microwave scattering in TFTR plasmas with reversed magnetic shear. They propagate in the ion diamagnetic drift direction with a frequency below the ion diamagnetic drift frequency in the frame of reference where E_r = 0. The variation of the fluctuation amplitude in the plasma core correlates with the variation of the local electron heat conductivity, suggesting that these fluctuations may be the cause of anomalous electron heat transport in these plasmas.