The dispersion prope9ies of the slow electromagnetic surface waves propagating across external magnetic field in planar metallic waveguides with plasma and dielectric filling on the harmonics of the electron cyclotron frequency are studied in this paper. The external steady magnetic field is supposed to be directed perpendicularly to the waveguide wall. Dielectric layer separates semibounded plasma from the metallic wall. The analytical research is carried out using the kinetic description for plasma particles, the mirror reflection model for the interaction between particles and plasma boundary. Skin depth of the surface cyclotron waves (SCW) is much greater than electron Larmor radius. Effect of the following parameters of the waveguide structures: dielectric constant and thicknes of the dielectric layer, plasma density value and number of the cyclotron harmonics, on the SCW dispersion is examined both analytically and numerically.

This paper is devoted to the theory of surface waves propagating across axis of symmetry in non-uniform cylindrical metal waveguides with plasma filling. The presented results are devoted to: first, studying an influence of plasma density non-uniformity on the features of these waves; second, studying an influence of an external magnetic fields' non-uniformity on their dispersion properties; third, studying possibility to sustain gas discharge by propagation of these waves under different operating regimes. The problems have been solved both analytically and numerically. Plasma particles are described in the framework of hydrodynamics; fields of the studied waves are determined by a set of Maxwell equations. Analytical research of the obtained equations is carried out by the method of successive approximation; adequacy of such approach is proved here as well. Numerical evaluations of the possibilities to observe experimentally the phenomena, which accompany propagation of these waves, are carried out.

The ICRF (ion cyclotron range of frequencies) mode conversion regime efficiently provides local electron heating. The efficiency of mode conversion could be enhanced due to the interference between the reflected waves (Fuchs V et al 1995 Phys. Plasmas 2 1637-47). Plasmas of large-scale tokamaks can include multiple mode conversion layers which results in a complicated picture of mode conversion. The 1D theory of mode conversion in plasmas with two ion-ion hybrid resonance layers is presented. Using the phase-integral method the analytical expression for the conversion coefficient is derived within a cold plasma model. The possible enhancement of the mode conversion coefficient in such plasmas is shown. The developed theory is used to analyze the role of carbon ions in the ( 3 He)H scenario of ICRF heating. As hot plasma effects may decrease the amount of power ultimately ending up on mode converted waves, a brief discussion of numerically obtained results but relying on a hot plasma model is included.

The current ramp up phase of ITER demonstration discharges, performed at JET, is analysed and the capability of the empirical L-mode Bohm-gyroBohm and CoppiTang transport models as well as the theory-based GLF23 model to predict the temperature evolution in these discharges is examined. The analysed database includes ohmic (OH) plasmas with various current ramp rates and plasma densities and the L-mode plasmas with the ion cyclotron radio frequency (ICRF) and neutral beam injection (NBI) heating performed at various ICRF resonance positions and NBI heating powers. The emphasis of this analysis is a data consistency test, which is particularly important here because some parameters, useful for the transport model validation, are not measured in OH and ICRF heated plasmas (e.g. ion temperature, effective charge). The sensitivity of the predictive accuracy of the transport models to the unmeasured data is estimated. It is found that the Bohm-gyroBohm model satisfactorily predicts the temperature evolution in discharges with central heating (the rms deviation between the simulated and measured temperature is within 15%), but underestimates the thermal electron transport in the OH and off-axis ICRF heated discharges. The Coppi-Tang model strongly underestimates the thermal transport in all discharges considered. A re-normalisation of these empirical models for improving their predictive capability is proposed. The GLF23 model, strongly dependent on the ion temperature gradient and tested only for NBI heated discharges with measured ion temperatures, predicts accurately the temperature in the low power NBI heated discharge (rms < 10%) while the discrepancy with the data increases at high power.Based on the analysis of the JET discharges, the modelling of the current ramp up phase for the H-mode ITER scenario is performed with particular emphasis on the 3 sensitivity of the duration of the sawtooth-free current ramp up phase to transport model. 4

No abstract