Characterization of arclike Ti vapor plasma on the high-voltage electron-beam evaporator

The generation mechanisms of vaporization and electron emission from the melted evaporator in an arclike Ti vapor plasma are diffident from those in typical cold cathode are plasma, but the ionization and excitation processes ol Ti vapor by electron impact are similar. The plasma expansion is strongly affected by the anode. However, this high-density plasma can be controlled by the anode voltage and/or emission current of an electron-beam gun. The relationship between the plasma parameters and the optical emission spectrum consisting of only Ti I (neutral) and Ti II (Ti+) is investigated. When anode voltage V-a increases from 20 to 60 V at the anode current I-a 30 A, J(i) increases from 6 to 12 A/m(2) while R-d decreases From 1.4 to 1.0 nm/s at the distance 0.45 m from the evaporator, and flux ionization increases from 40% to 100%. The content of the high excited species of Ti increases. On the other hand, when I-a increases from 10 to 60 A at V-a 30 V, J(i) and R-d increases from 4 to 38 A/m(2) and from 0.8 to 2.2 nm/s, respectively, and flux ionization Increases from 20% to 80%. The content of the high excited species of Ti increases, which suggests the formation of a ''potential hump'' due to positive space charge. The calculated ion and excited species production rates (where the minimum ion production rate required to sustain this plasma, 2.7 x 10(24) ions/m(3)s, is much higher than that to sustain a typical glow discharge, 7.6 x 10(20) ions/m(3)s) are related to fi and the optical emission intensity, respectively. Furthermore, the behavior of J(i) agrees with that of the optical emission intensity of Ti II (376.0 nm). (C) 1997 American Vacuum Society.