EDGE TURBULENCE SPECTRUM ALTERATIONS DRIVEN BY RESONANT FIELDS

An ergodic magnetic structure is generated in the TBR-1 tokamak bounda ry to handle heat flux and minimize impurity generation. In this work, the effect of this structure on the plasma edge turbulence is investi gated. Thus, spectral alterations driven try perturbing magnetic field s created by resonant helical windings are observed in the small tokam ak TBR-1. The investigated oscillations are detected with an array of Langmuir and magnetic probes. Spectral and bispectral analyses reveale d significant changes induced by the resonant helical windings, mainly in the MHD frequency band. Thus, whereas the known Mirnov oscillation amplitude reduction is observed, the density and potential oscillatio n spectra are slightly affected. However, the bispectral analysis show s a clear reduction of the wave-wave mode coupling in the MHD frequenc y range, while the high frequency turbulent coupling is spreadly reduc ed.