Electrostatic edge turbulence on CASTOR tokamak

The electrostatic edge turbulence in the Castor tokamak was studied by a movable triple Langmuir probe connected with a three-channel analog correlator. Two channels operated in the autocorrelation mode and served for monitoring the RMS values of fluctuations of the density and poloidal electric field. The third channel operated in the cross-correlation mode and monitored directly the radial turbulent flux. In the combined inductive and lower hybrid current drive tokamak regimes, the electrostatic edge turbulence decreased substantially. This suppression of turbulence is apparently a dominant mechanism for the observed improvement of particle confinement. (J.U.). 3 figs., 8 refs