O-mode Doppler reflectometer has been successfully developed as an important di-agnostic system on HL-2A.It can be used to measure the turbulence propagation in both plasmaedge and confinement zone.The Doppler reflectometer system consists of two fixed frequencyhomodyne receivers:15 GHz(corresponding to cutoff density of 0.3×10^(19)m^(-3))and 33 GHz(cot-responding to cutoff density of 1.35×10^(19)m^(-3)).The Doppler reflectometry principle and theexperimental arrangements on HL-2A are presented.Meanwhile,the experimental Doppler reflec-tometric spectra under different discharge conditions,with and without ECRH,were obtained.Furthermore,the turbulence propagation velocity change and the profile were also observed indifferent discharge conditions.
A three channel CO_2 laser forward scattering diagnostic system was set up to studythe core plasma density fluctuation in the HT-7 tokamak. The range of the wavenumber mea-surement in the poloidal direction was k_θ = 12 cm^(-1) to 34 cm^(-1) and the wavenumber resolutionwas △k = 2.5 cm^(-1). The wavenumber spectrum, the coexisting modes and the micro-instabilityeruption in experiments are presented.
