[en] We present numerical results of a 1-D (poloidal), time dependent code for the description of ion impurity transport on a given tokamak magnetic surface, in the presence of momentum sources such that, as observed in neutral beam injection experiments, the toroidal rotation velocities be comparable to or larger than the impurity thermal speed. We show that the densities, the velocities and the ambipolar potential reach a quasi steady state characterized by significant poloidal gradients, on a time scale of the order of the collision time, i.e. faster than the radial diffusion scale. To obtain this steady state a phenomenological drag force needs be introduced; we find that a purely classical, gyroviscous force alone is apparently insufficient to obtain a steady state, within the framework of the present model which retains only the zero-th order, in the Larmor radius expansion, ion-impurity friction

[en] To simulation the two-dimensional axisymmetric plasma scrape-off layer in a tokamak, a finite element fluid model is developed in this report. This plasma's (with different electron and ion temperatures) evolution is driven by the interaction between plasma and neutral recycling at the walls

[en] When the beam driven toroidal plasma rotation reaches thermal velocity the particle density and the ambipolar potential can develop strong poloidal variations in the flux surface. The rapid time evolution of the thermal velocity, the change in toroidal plasma rotation, and the plasma flow velocity components in the flux surface are calculated. These results are evaluated numerically using a spectral code to describe the strong poloidal couplings. Results are compared to data from the ASDEX tokamak

[en] A finite difference time-dependent algorithm for the steady-state solution of conduction-convection problems is discussed. The scheme is applied to a boundary layer problem; in the region where steep gradients occur a higher grid resolution is used. The accumulated mesh is mapped to an equidistant grid by a suitable space-transformation. A corresponding time-transformation has the potential to reduce the computational effort. (orig.)

[en] Within the framework of a simplified scrape-off layer model the scrape-off length lambdasub(q) for the heat flux is shown to depend on the plasma elongation k to first order in (k-1). Power deposition profiles are calculated for a typical toroidal limiter located at the midplane of the plasma chamber

[en] We present here the numerical solution of a one-dimensional (along the magnetic field) 1-fluid time dependent set of plasma scrape-off layer (SOL) model equations (particle, momentum and energy balances) by means of finite element (FE) discretization of the space coordinate. The results are compared with those of the SOLID finite difference (FD) code and good agreement is found between the two. This shows the potential of the FE to work also in the presence of strong convection, as is the case near the divertor plate or limiter - a feature which if confirmed in the two-dimensional case will make them particularly attractive for SOL simulation. (author)

[en] Computational Fluid Dynamics (CFD) techniques have been proposed and applied in a series of papers to analyze cable-in-conduit conductors (CICC) for the International Thermonuclear Experimental Reactor (ITER). Previous work on the pressure drop in the central channel of ITER CICC is extended here to the problem of combined heat and momentum transfer. The CFD model, solved by the FLUENT commercial code, is first validated against 2D and 3D data from compact heat exchangers, showing good agreement. The Colburn analogy between the friction factor f and the Nusselt number Nu is not verified in the considered 2D geometries, as shown by both experiment and simulation. The validated CFD model is finally applied to the 3D analysis of central channel-like geometries relevant for ITER CICC. It is shown that the heat transfer coefficient on the central channel side stays relatively close to the smooth-pipe (Dittus-Boelter) value

[en] A methodology for measuring instantaneous thermal loads on a portion of the Frascati Tokamak Upgrade (FTU) poloidal limiter was developed; such a methodology is based upon the processing of experimental data recorded by thermocouples and an infrared detector. By a proper calibration procedure, the instantaneous surface temperature of a portion of the limiter can be obtained; the deconvolution of the time-resolved limiter surface temperature provides time-resolved thermal loads. In this paper the apparatus is described and some examples of elaborated data are given

[en] Detailed edge plasma modeling in the presence of moving fronts requires adaptive meshes. We use an adaptive anisotropic triangular mesh generator for solving a steady state 2-D anisotropic nonlinear conduction problem with strongly nonlinear sinks. This equation can be thought of as a simplified scalar model of energy transport in a scrape-off layer (SOL) plasma, under the action of ionization and/or impurity losses. The problem is solved with finite elements using a triply nested loop of iterations. (orig.)

[en] We present here the validation of two computer models for the ITER CICCs based on experimental data produced at CEN-Grenoble. The models, implemented in two finite element computer codes, describe compressible helium flow in a Cable-in-Conduit with central cooling hole. The main difference between the two is in the treatment of the transverse mass and energy transfer between the helium flow in the cable bundle and that in the cooling hole. Both models give satisfactory results compared to the measurements of slow transients, and the more complete of the two shows a better agreement with the experiments