Electron Density and Fluctuation Measurements by Using a Frequency Multiplied Microwave Interferometer in the GAMMA 10 Anchor Cell

In GAMMA 10 two types of low frequency plasma fluctuations have been observed in the central cell by several diagnostics. One of which is the electron drift mode rotating azimuthally in the direction of electron diamagnetic drift rotation observed during ion cyclotron range of frequency heating (ICH). Recently a new interferometer has been installed in the mid-plane of the west anchor cell in order to investigate plasma density and density fluctuations in the anchor cell. By using the new interferometer, line-integrated density fluctuations are measured in the anchor cell and are compared to fluctuations in the central cell obtained by conventional interferometer systems. Density fluctuations around 10 kHz are observed in both cells during the ICH period and they are suppressed during the formation of axial confining potentials by electron cyclotron heating (ECH) in the plug regions.