Experimental investigations of plasma fluctuations and performance on C-2W

C-2W is an advanced beam driven Field Reversed Configuration (FRC) fusion device, in which plasma sustainment with the total temperature of over 4 keV has been demonstrated. C-2W is equipped with a state-of-the-art Thomson Scattering (TS) system that has 16 spatial cords. The DC output channels of TS polychromators, which are used to calibrate the system spectral response and monitor the background plasma radiation for measurement uncertainty analysis, can also be used to measure plasma fluctuations. The radiation recorded in these DC channels is mainly bremsstrahlung in the range of 850 - 1000 nm, which is determined by the density fluctuations at Te ~ 100 - 300eV. With this setup, fluctuations are observed at the edge of C-2W plasma with peak amplitudes measured where the maximum density gradient occurs. The experimental observation and possible candidate mechanisms will be presented.