The results of predictive self-consistent modelling of plasma parameters in low (L) and high (H) confinement modes by the one-dimensional transport code RITM, with particular emphasis on the properties of the edge transport barrier, are presented and discussed. The same transport model is used under both Land H-mode conditions and includes contributions from ion temperature gradient (ITG), trapped electron, drift Alfvén (DA) and drift resistive ballooning instabilities described in the fluid approximation. The computations predict the formation of the edge transport barrier at a high enough heating power due to stabilization of ITG and DA modes, dominating the edge transport in the L-mode, through the effects of the density gradient and the pressure gradient at low collisionality, respectively. The calculated radial profiles and scalings for pedestal and confinement characteristics are compared with measurements on JET, DIII-D and JT-60U tokamaks.

A sharp interface model of crack propagation as a phase transition process is discussed. We develop a multipole expansion technique to solve this free boundary problem numerically. We obtain steady state solutions with a self-consistently selected propagation velocity and shape of the crack, provided that elastodynamic effects are taken into account. Also, we find a saturation of the steady state crack velocity below the Rayleigh speed, tip blunting with increasing driving force, and a tip splitting instability above a critical driving force.

Melting of a bicrystal along the grain boundary is discussed. A triple junction plays a crucial role in the velocity selection problem in this case. In some range of the parameters an entirely analytical solution of this problem is given. This allows us to present a transparent picture of the structure of the selection theory. We also discuss the selection problem in the case of the growth of a ''eutectoid dendrite.''

The measured K α spectra of He-like argon were used to determine the densities of H-, He-and Li-like argon ions in ohmically heated plasmas in the tokamak TEXTOR. The obtained ratio of the densities for the Li-and He-like ions shows a significant deviation from coronal equilibrium. In order to interpret these results numerical modelling of the impurity transport was performed by the code RITM with neoclassical and anomalous contributions to the transport coefficients. The measurements show that the transport in the plasma core is much higher than that predicted from the model and has a strong correlation with the line averaged density. This paper also demonstrates the unique ability of the He-like spectra to separate the transport properties and the charge-exchange processes in the plasma.

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