Fluctuation Characteristics in Detached Recombining Plasmas

Fluctuation in detached recombining plasmas has been investigated experimentally in the linear divertor plasma simulator, NAGDIS‐II. As increasing neutral gas pressure, floating potential fluctuation of the single Langmuir probe and the target plate installed at the end of the NADIS‐II device becomes larger and bursty negative spikes are observed in the signal associated with a transition from attached to detached plasmas. The fluctuation property has been analyzed by using Fast Fourier Transform (FFT), probability distribution function (PDF). The PDF of the floating potential fluctuation in the attached plasma condition obeys the Gaussian distribution function, on the other hand, the PDF in detached plasma shows a strong deviation from the Gaussian distribution function, which can be characterized by flatness and skewness.