음이온이 배경플라즈마의 전자에너지분포에 미치는 영향

Abstract

Negative ion plasmas are generated by adding electronegative gas, sulphur hexafluoride (SF6), to a background argon (Ar) DC filament plasma with parameters of n0 ~ 10^10 cm^-3 and Te ~ 2 eV . The heating current of the thoriated tungsten filament was in the range of 20.5 - 21.5 A and the plasmas were generated under a discharge condition of 100 V / 0.4 A. The amount of negative ions was controlled by adjusting the ratio of flow rate of SF6 = 0 - 10% to that of Ar. Current - Voltage (I-V) characteristics were acquired by cylindrical and planar electric probes which have distance of 3 cm and the measured I-V characteristics were analyzed in order to calculate plasma parameters and also to obtain electron energy distribution function (EEDF). Explanations for the changes of plasma parameters related to electron such as floating potential (Vf) and electron temperature (Te) are suggested due to the increase of negative ion. The explanations are also compared with the EEDF results which shows broadened electron energy distribution due to the increase of negative ion.