Beryllium fluxes into the ITER tokamak plasma due to sputtering of the first wall by D and T atoms leaving the plasma were estimated. The energy spectra of deuterium and tritium atoms leaving the plasma were modeled using the DOUBLE-MC code. The flux of beryllium atoms entering the plasma was estimated to be 6.5 × 10 17 atoms s −1 m −2 . Azimuthal anisotropy of the fluxes of atoms leaving the plasma was taken into account, which increased the estimate of the beryllium flux by 15% compared to that in the isotropic case. With the typical ITER plasma confinement times of 3-5 s, this means that the concentration of beryllium impurities can be 2.5%-4.2% of the mean ion plasma density. Such a high content of beryllium ions in the region close to the separatrix can lead to significant sputtering of the divertor with multiply charged beryllium ions. The proposed model allows estimation of the flux of sputtered tungsten atoms into the near divertor plasma. By varying the density of the gas-plasma target and the electron temperature on the separatrix, one can reduce the tungsten impurities influx into the plasma.

No abstract

No abstract

No abstract

The results of modeling the sputtering coefficients of polycrystalline beryllium by hydrogen isotopes in the range of collision energies of 8 eV-100 keV and their dependences on the angle of incidence of the beam on the surface are presented. This data is necessary for estimating the sputtering of the first wall in the ITER tokamak made from beryllium. A strong surface shape influence on obtained results is shown. The limiting cases of a flat potential barrier (smooth surface) and a spherical potential barrier (a surface consisting of spikes) are considered. The effect of collision cascades on the sputtering coefficient has been established. The dependences of the average depth of sputtered particle formation on the bombarding particles energy are obtained for various angles of beam incidence on the target. The energy spectra and angular dependences of the ejection of sputtered particles are calculated for different energies of bombarding beam atoms. It is shown that the presence of an attractive well in the potential of an incident particle surface changes the sputtering coefficient dependence on incidence angle at small glancing angles. Keywords: Sputtering coefficients, energy and angular distributions of sputtered particles, interatomic potential, hydrogen isotopes, beryllium.