  The ITG and TEM instabilities with quasi-coherent spectra have been
identified experimentally, by the newly developed far-forward collective
scattering measurements in J-TEXT tokamak Ohmical plasmas. The ITG mode has
characteristic frequencies in the range of 30-100kHz and wavenumber of
k_\theta\rho_s<0.3. After the plasma density exceeds at critical value, the ITG
mode shows a bifurcation behavior, featured by frequency decrease and amplitude
enhancement. Meanwhile, the ion energy loss enhancement and confinement
degradation are also observed. It gives the direct experimental evidence for
ion thermal transport caused by ITG instability.
