Erosion of hot refractory metals caused by low-energy ions

The erosion of polycrystalline tungsten at temperatures in the range 1000--1900 K by argon ions at energies in the range 50--100 eV has been studied experimentally. A theory is derived for the sputtering rate under these conditions. It is shown that the sputtering rate is affected not only by the ion energy but also, and strongly, by the surface temperature. A ''hotspot'' model is used to derive a semiempirical equation for the sputtering coefficient as a function of the ion energy and the target temperature. The specific erosion of cathodes in high-current discharges caused by sputtering and evaporation is calculated