부산대학교 도서관

Low-frequency/long-wavelength density turbulence is found to be reduced within the volume enclosed by an electron thermal internal transport barrier generated with lower hybrid microwave heating in the JET tokamak. The turbulence reduction coincides with a region (typically r/a<0.4) of negative, or reversed magnetic shear s and reduced electron thermal diffusion χ_e. In the tokamak edge region (r/a>0.8), the turbulence amplitude is also reduced coinciding with large positive magnetic shear s>1. Estimates of the core turbulence wavelengths (λ_⊥> 0.1 m) are not in agreement with expectations from electron temperature gradient instabilities.