Modeling of the Sputtering Rate of the Tokamak First Wall by Atoms of Hydrogen Isotopes in the Near-Wall Plasma

Abstract

A method for calculating sputtering of the tokamak first wall by fast charge-exchange neutral atoms of hydrogen isotopes in the near-wall plasma has been proposed. The application of the method has been shown by the example of sputtering of the assumed first-wall materials under the near-wall plasma conditions in the ITER tokamak. Using the BM1D2V code based on the ballistic model of hydrogen recycling kinetics in the tokamak main vacuum chamber, the velocity distribution function (VDF) of neutral atoms and molecules of hydrogen isotopes in the near-wall plasma has been calculated. Using the calculated VDFs, the sputtering rate of beryllium, tungsten, and boron from the surface of the first wall of the tokamak vacuum chamber in a typical ITER divertor operating mode has been estimated. The reflection coefficients of atoms of hydrogen isotopes from the first wall used in the ballistic model and the sputtering coefficients have been calculated using the SDTrimSP code.