A Method for Estimating the Sheath Edge of Plasma Ion Sources

An empirical method has been used in this paper to estimate the sheath edge of plasma ion sources. Based on Kovaleski´s hypothesis in 2006 that the sheath edge from an unmagnetized plasma is coincided with a critical electric field magnitude contour, the sheath edges simulated by a trajectory code were used to calculate E_p and to fit E_p as a function of T_e and n_e0. A test shows that only half iterations are needed when the initial sheath is set by the empirical method of this paper. This indicates that the using of the empirical method can save much computing time. The deviation of the expression of E_p in Kovaleski´s paper and this paper is also discussed. The deviation may be due to the different type of used codes and that the plasma distribution will influence the electric field distribution in sheath edge calculations.