CHARACTERISTICS OF TRANSIENT PLASMA LAYERS PRODUCED BY IRRADIATION OFGRAPHITE TARGETS BY HIGH-POWER QUASI-STATIONARY PLASMA STREAMS UNDER THE DISRUPTION SIMULATION CONDITIONS

Simulation experiments to model the situation occurring at the diverto r plates during disruptions and ELMy H-modes of tokamak were carried o ut with plasma streams generated at the Kharkov QSPA. The facility ult imate plasma parameters were as follows: plasma energy density - above 2 kJ/cm(2), proton energy -0.9 keV, plasma density - 10(16) cm(-3), p ulse duration - 0.1-0.15 ms. Graphite targets of different sizes utili zed in these experiments, It was shown that high density target plasma layer, with densities up to 6 . 10(17) cm(-3) were formed above the t arget surface, when incident plasma interacted with target, and sustai ned during the whole pulse, Density and thickness (usually within 3 to 5 cm) increased with increasing incident plasma power and target surf ace. The main part of incident plasma energy (approximate to 90%) is a bsorbed by the transient layer on the first 2-3 cm of its thickness. T he average erosion coefficient of the graphite under the influence of incident plasma was of the order of 1 mu m/kJ.