ACTIVE PLASMA BOUNDARY SHEATH WITH ELECTRON-EMISSION

The influence of electron emission on the properties of the space char ge sheath between plasma and wall is investigated theoretically using models of the stationary sheath. Especially, the following effects hav e been considered: 1) the change of plasma parameters by electron emis sion, 2) the sheath in case of space charge limited emission, and 3) t he processes of plasma-induced electron emission causing a feedback lo op between plasma parameters and emission yield. Essential parameters of the sheath (e.g. potential drop, power flux density), of the wall s urface (temperature, field strength, emission yield, Joule heat genera tion) and of the adjacent plasma layer (emission-caused change of the electron temperature) have been calculated under self-consistent condi tions. From the obtained results several ways are discussed indicating the development towards sheath instability and ending in the generati on of plasma-induced are spots.