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It is believed that radial anomalous transport in tokamaks is caused by plasma turbulence. Using infa-red laser scattering techniques on the Tore Supra tokamak, statistical properties of the density fluctuations are studied as a function of the scales in ohmic as well as additional heating regimes using the lower hybrid or the ion cyclotron frequiencies. The probability distributions are compared to a Gaussian in order to estimate the role of intermittency which is found to be negligible. The temoral behaviour of the three dimensional spectrum is thoroughly discussed; its multifractual character is reflected in the singularity spectrum. The auto-correlation coefficient is shown to reflect a short time coherence of the dissapative structures as well as hteir long-tern incoherence and statistical independence. We also put forward the existance of fluctuations transfer between two distinct but close wavenumbers. A rather clearer image is thus obtained about the way energy is transferred through the turbulant scales.

Additional information

Authors: ANTAR G, LPMI - Ecole Polytechnique (FR)
Bibliographic Reference: Article: Plasma Physics and Controlled Fusion, 40 (1998), 947-966
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