Observations of an increase in electron density triggered by electrode biasing are reported in the Tohoku University Heliac (TU-Heliac). The biased electrode, which is located deep inside the plasma, induces a strong positive radial electric field, after which the line density increases by a factor of 2, the electron density profile steepens and the fluctuation level drops. We estimate the damping force opposing poloidal rotation experimentally and compare it with various versions of the neoclassical theory. The experimental results agree in that the measured damping force has a local maxima at |MP| = 1-2 and tends to be proportional to Mp in the high speed region (|MP| > 3-6), where Mp is the poloidal Mach number. For |Mp| < 1-2, however, the dependence of the measured damping force on Mp differs a little from theoretical predictions.
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