SPECTRAL CHARACTERISTICS OF LOW-FREQUENCY TURBULENCE IN TOROIDAL COLLISIONAL MAGNETOPLASMA

The dispersion and spectral characteristics of low-frequency fluctuati ons excited in collisional toroidal magnetoplasma is reported. The pla sma produced under the operating conditions have magnetized electrons, unmagnetized ions, E\\del n perpendicular-to B and del n antiparallel to effective gravity g. The low frequency (<ion-gyrofrequency) electr ostatic fluctuations observed in density and potential are turbulent, travel mainly in azimuthal direction and are excited by the cross-fiel d instability. The spectral indices of the k spectra for the density a nd potential fluctuations, as computed using pair probe technique, are -3.8+/-0.5 and -6.0+/-0.6, respectively. These results are in good ag reement with the in situ measurements of fluctuations in equatorial el ectrojet and the earlier laboratory experiments on the cross-field ins tability. Numerical simulations and nonlinear theories, however, predi ct flatter spectra.