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The experiments on large tokamaks on measuring the hydrogen isotope pressure in the near-wall or divertor plasma are briefly described. Based on the analysis of exchange fluxes between the plasma and the wall it is stated that the plasma action, with respect to hydrogen sorption by graphite components of the tokamak first wall, is identical to materials exposure in the atmosphere of molecular hydrogen at pressures of 1–10 3 Pa and temperatures of 1200–1700 K. Within these ranges of pressures and temperatures RG-Ti-91 and USB-15 graphites are shown to be impermeable to molecular hydrogen in contrast to easily permeable POCO-AXF-5Q. Sorption capacity of well-treated dense graphites is about 10 2 appm. Sorption capacity of materials is increased to (1–3)×10 4 appm with defects like unsaturated carbon bonds, introduced into the above materials by mechanical treatment, ion irradiation, graphite gasification (exposure at 1200 K, 133 Pa during 1 h). At the same time permeability of graphites is increased to molecular hydrogen. Graphite modification by boron retards the rise of sorption capacity. The hydrogen sorption process is described as the filling of two sets of traps, i.e. weak traps arranged over the boundaries of carbon materials and deep traps arranged in the volume of separate crystallises. Russian-made graphites RG-Ti-91 and USB-15 can be used in large tokamaks as divertor and first wall tiles, respectively.

This article examines the calcination of raw coke in hearth and chamber furnaces. Three coke samples with identical degrees of calcining were taken from each furnace. The heating rate was calculated from measurements of the coke temperature as it moved in the furnace under conditions of a stable and characteristic calcining regime. The coke temperature was measured by means of a chromel-alumel thermocouple. Electric resistivity and carbon and hydrogen contents are practically identical for the cokes calcined in the hearth and chamber furnaces. The difference between the quality indexes of the cokes is attributed to the difference in the heating rates. The results indicate that a major disadvantage of the hearth furnace is its high heating rate. It is suggested that the hearth furnace should not be used in calcining cokes that must meet rigid quality requirements.

1. A technique has been developed for the chemical etching of carbon-graphite materials prepared by thermomechanical treatment. 2. It is shown that, by employing the chemical etching technique, it is possible clearly to reveal the structure in completely smeared microsections obtained by polishing graphitized materials.

A set of highly bent crystal monochromators made from formed pyrolytic graphite has been tested using synchrotron‐radiation beams from the storage ring VEPP‐3. These crystals were used in the following devices: short‐focus wide‐band monochromator and cylindrical dispersion filter of secondary (fluorescent) radiation.