Density fluctuations in tokamak plasmas. After a decade of research what can we say

The results from a wide range of experiments on density fluctuations in tokamak plasmas are summarized. The density fluctuations are turbulent, having a broad spectrum of wavevectors and a broad spectrum of frequencies at each wavevector. The fluctuation amplitude is inversely proportional to the gradient length of the density and the mean wavevector of the fluctuations. There is evidence that the observed value of the mean wavevector of the fluctuations is proportional to the toroidal magnetic field, but is insensitive to temperature and position in the plasma. The fluctuation spectrum is also insensitive to collisionality. The relationship of these fluctuations to magnetic and potential fluctuations in the plasma and to plasma transport is briefly discussed