Journal Article

Measurement of the Characteristics of Fine-Grained Graphite Used as a Material for the First Wall of the T-15MD Tokamak

Begrambekov, L. B., Zakharov, A. M., Ayrapetov, A. A., Puntakov, N. A., Arkhipov, I. I., Savvin, N. O., Grashin, S. A., Grunin, A. V., Dovganyuk, S. S.

2023

Overview

The characteristics of fine-grained graphite, which will be used as the material for plasma-contacting elements of the T-15MD tokamak, are studied in this work. The density and porosity, thermal diffusivity and thermal conductivity, sizes of the crystalline grains and the amount of impurities in graphite are measured. The measurement results are compared with the corresponding characteristics of MPG-6, MPG-7, and MPG-8 graphite samples. The nature of the retention of hydrogen isotopes and methane in graphite and the conditions of desorption are determined depending on the temperature of preliminary annealing, its duration, and the exposure time of annealed samples in atmospheric gas under normal conditions. The effect of irradiation with deuterium ions of various energies on the regularities of hydrogen trapping and desorption is also considered. In all cases, attention is paid to the effect of experimental conditions on the retention and desorption of hydrogen, which remained in graphite from the time of its production and was trapped during exposure to air. Based on the obtained data and taking into account the expected conditions in the chamber of the T-15MD tokamak, the optimal conditions for annealing of graphite supplied from the manufacturer are identified, and the temperatures of the tokamak elements in contact with the plasma, which contribute to the removal of hydrogen from the graphite lining, are determined.

• Publisher: Pleiades Publishing,Springer Nature B.V
• Subject: Accuracy / Annealing / Carbon / Chemistry and Materials Science / Desorption / Deuterium / Graphite / Heat conductivity / Hydrogen isotopes / Lasers / Materials Science / Plasma / Surfaces and Interfaces / Thermal conductivity / Thermal diffusivity / Thin Films / Tokamak devices