ELM-like activity has been recently observed in TJ-II, in plasmas with stored energy above 1 kJ. The plasma is observed to develop bursts of magnetic activity (seen in Mirnov coil signals) which are followed by a large and distinct spike in the Hα signal. An increase in electrostatic and magnetic fluctuations at the plasma edge and a cold pulse towards the plasma centre are also characteristics of these events. In addition, the electron temperature profile locally flattens at the plasma radius where the temperature is in the range 100-200 eV. This flattening can be explained in terms of enhanced electron heat conductivity. Between ELM-like events the electromagnetic turbulence at the edge decreases and the Te profiles recover their former shapes. This activity is probably triggered by a resonant m = 2, n = 3 mode.

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Previously it has been shown that there is no lack of plasma induced magnetic field components that are strongly dependent on the plasma profiles. Here, a new method for collecting and interpreting magnetic data is presented. The properties of the magnetic probe system needed for the determination of both the plasma pressure profile and the current distribution are discussed. Considerable attention has been given to the evaluation of the required accuracy of magnetic measurements. Possible ways to simplify the general technique for the solution of particular problems are also discussed. As an example the Large Helical Device (LHD) configuration is referred to. A brief description of the peculiarities of plasma equilibria in this system relevant to the problem under consideration is presented. Emphasis is given to the cases in which plasma induced destruction of the plasma boundary is important

A method is developed for studying MHD equilibrium and stability of plasmas confined in toroidal systems with a large constant magnetic field and a small field which varies rapidly in space. The method is used to obtain a system of magnetohydrodynamic equations averaged over the period of the rapidly varying field. In this form, the problem is greatly simplified, and the equations become similar to those used for axisymmetric tokamaks, for which methods have now been developed in some detail. -The problem of the limiting plasma pressure for equilibrium and stability in a stellarator is analysed, and it is shown that, within the framework of an ideal MHD model, 0 = 2P/B 2 can be larger than 10% in systems with large shear and partial compensation of the magnetic fields produced by the diamagnetic currents. Also the question of toroidal drift compensation and, as a result, of the decrease in the neoclassical diffusion coefficient is discussed.

The three dimensional (3-D) and axisymmetric (2-D) magnetic fields produced by currents flowing in plasmas that are confined in stellarators with a nearly planar geometrical axis are investigated. Using the Green's function method to solve the 3-D linear equation derived previously, a simple procedure is presented here to determine the structure of plasma induced external magnetic fields in stellarators. A detailed numerical analysis of the values of the external 3-D magnetic fields and their dependences on the plasma profiles is performed. Analytical formulas are derived that could be useful for estimations. The possibility of using the measurements of these fields for the experimental identification of the magnetohydrodynamic (MHD) equilibria is considered. Also discussed are some interesting aspects of the influence of the magnetic hump on the value of the Pfirsch-Schliiter currents (that appear in recent Heliotron-E experiments) and the influence of different features of the vacuum magnetic field on the dipole component of plasma induced field is classified. The results of calculations related to the modern experiments are presented, and the case that may be typical for future experiments is also considered.