Electron Velocity Distribution at a Sheath Edge in the Presence of Secondary Electron Emission From a Metal Surface

To estimate the reduction of the electron temperature at a sheath edge in the presence of secondary electron (SE) emission from tungsten (W) and beryllium (Be), we combined the ELECTRAN code, which calculates SE emission from metals, with a kinetic code that used a particle‐in‐cell (PIC) technique. Because the emitted electrons were accelerated toward the bulk plasma by the sheath electric field, the decrease of the effective temperature of electrons at the sheath edge was attributed to the lower sheath electric field. The electron yield for W (high‐Z) was higher than that for Be (low‐Z). SE emission decreased the sheath electric field. Therefore, the effective temperature of electrons for W is lower than that for Be (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)