The Experimental Study Of Low Frequency Instability And Laser Induced Fluorescence Diagnostic In Magnetized Plasma Column

A linear magnetized steady plasma device was successfully set up in USTC. Hot filament DC discharge and RF helicon discharge applied in the device provide a wide range of plasma parameters, such as density, electron temperature.The low frequency fluctuation observed in the magnetized plasma column was identified as density gradient driven drift wave. From the analysis of bi-spectrum, nonlinear energy transfer function and amplitude correlation, strong wave-wave interaction was observed and the energy was transferred from high frequency part to low frequency. Some low frequency zonal flow like structures were also found. The drift instability induced radial transport exceeds the classical transport, but is below the Bohm value.Laser Induced Fluorescence diagnostic was build up. The cheap and ease-use diode laser was chosen as the pump laser source, instead of the expensive dye laser. It was found that the metastable state argon ions were mostly produced via the one-step ionization. The intensity of induced fluorescence was optimized by carefully choosing the proper neutral pressure, discharge voltage and pumping laser power. From the recovery of the background fluorescence, we deduced the ion diffusion coefficient, which agreed with the result from the damping of Ion Acoustic Wave.