Diagnostics of Metal Plasma in Radio Frequency Glow Discharge during Electron Beam Evaporation**Supported by the National Natural Science Foundation of China under Grant No 51201051, an Opening Project from the State Key Laboratory of Advanced Welding and Joining at Harbin Institute of Technology under Grant No AWPT-M10, and the Fundamental Research Funds for the Central Universities under Grant No HIT.NSRIF.2012041.

Abstract

A new method for generating metal plasma via radio frequency (rf) glow discharge during electron beam evaporation is proposed. A probe array and an emission spectrometric analysis are employed to identify the metal plasma during rf glow discharge. Spectral results reveal that the Ti metal vapor is ionized and forms a metal plasma via rf glow discharge. The dependence of the emission intensities of Ti+ and Ti atoms on rf glow discharge parameters is investigated. The results show that, as rf power increases, the emission intensities of Ti+ are enhanced while the emission intensities of Ti atoms are suppressed due to a constant Ti atom flux and an increasing Ti+ flux. Furthermore, the emission intensities of Ti+ and Ti atoms increase with the electron-beam current. The influence of rf glow discharge parameters on the ion-beam current density is also studied. The results show that the ion-beam current density rises with increasing the rf power and the electron-beam current. The ion-beam current density at 4-cm radial distance doubles from 8 × 109/cm3 up to 1.7 × 1010/cm3 with increasing the rf power from 90 to 240 W and it increases almost five-fold in the electron-beam current range of 170–230 mA at 10-cm radial distance. Additionally, the increasing ratio of the ion-beam current density at the large radial distance is greater than that in the central region resulting from the driving force which is brought about by a pressure difference and the discharging action.