Upgradation of the dual-HCN collective scattering system for measuring turbulence evolution on the J-TEXT tokamak

The dual-HCN collective scattering system on the J-TEXT tokamak has been modified and upgraded for measurements of turbulence characteristics under different confinement regimes. A position- and angle-adjustable receiving module was integrated to measure density fluctuation at varied spatial locations and wavenumbers. A power supply with lower ripple was adopted to suppress frequency oscillation in the intermediate frequency output signal. Measurements of density fluctuations at various positions and wavenumbers were performed to verify the system’s spatial and wavenumber resolution. Temporal evolution of density fluctuations was observed during density limit onset and internal transport barrier formation. Experimental results confirm that the upgraded system is well suited for investigating turbulence evolution and confinement transitions.