Density Fluctuation Measurements of the GAMMA 10 Plasma by Using the Fraunhofer Diffraction Method

We applied Fraunhofer diffraction (FD) method to plasma density fluctuation measurement in GAMMA10. In GAMMA10 the drift-type fluctuation in the electron density and potentials and its suppression with application of electron cyclotron heating (ECH) are observed. The FD method can measure the fluctuation spectra in detail. We successfully obtained the density fluctuation spectra and its suppression with application of ECH by using FD method for the first time.