Erosion of tungsten by self-sputtering and light ion irradiation at oblique angles of incidence

Abstract

Tungsten is being considered as plasma facing material in next step fusion devices. The advantage of this material is its high surface binding energy and consequently its low physical sputtering yield by light ions. The drawback is the low tolerable limit of this impurity in the fusion plasma. However, this material may be a favorable choice for operation at low plasma edge temperature. This paper provides values of sputtering yields for self-sputtering of tungsten as a function of the angle of ion incidence. Sputtering yields are measured are measured in the range between 300 eV and 2 keV and between normal incidence and 60° to normal. Tungsten shows a strong angular dependence of the yield. A self-sputtering yield of tungsten, y =1, is reached at an angle of incidence =42° at an impinging energy E =350 eV. The results are compared with computer simulation calculations. The dependence of the sputtering yields on the structure of the target material was also investigated. In addition, the physical sputtering yields of tungsten by the light ions D, T and He as a function of angle of incidence and impinging particle energy were calculated. The results imply that a self-sputtering yield of tungsten y E