O-mode Doppler reflectometer has been successfully developed as an important diagnostic system on HL-2A. It can be used to measure the turbulence propagation in both plasma edge and confinement zone. The Doppler reflectometer system consists of two fixed frequency homodyne receivers： 15 GHz （corresponding to cutoff density of 0.3×10^19 m^-3） and 33 GHz （corresponding to cutoff density of 1.35× 10^19 m^-3）. The Doppler reflectometry principle and the experimental arrangements on HL-2A are presented. Meanwhile, the experimental Doppler reflectometric spectra under different discharge conditions, with and without ECRH, were obtained. Furthermore, the turbulence propagation velocity change and the profile were also observed in different discharge conditions.
A three channel CO2 laser forward scattering diagnostic system was set up to study the core plasma density fluctuation in the HT-7 tokamak. The range of the wavenumber measurement in the poloidal direction was kθ= 12 cm^-1 to 34 cm^-1 and the wavenumber resolution was △k = 2.5 cm^-1. The wavenumber spectrum, the coexisting modes and the micro-instability eruption in experiments are presented.
