Diagnostics of Metal Plasma in Radio Frequency Glow Discharge during Electron Beam Evaporation

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.