Ion Charge State Distribution And Ion Velocities In The Titanium Hydride Cathodic Vacuum Arc Plasmas

The time-resolved ion charge state distribution (CSD) and the charge state resolved ion velocities in the titanium hydride cathodic vacuum arc plasmas have been measured using a time-of-flight (TOF) mass spectrometer. Besides H+ and Tii+ existing in the plasmas with H+ and Ti2+ dominating, diatomic molecule ions of H are detected as neutral gas of hydrogen is released from the titanium hydride cathode during the discharge. The results of the experiment show that the released neutral gas has distinct effects on the ion CSD and velocities. A change of particle fraction has been observed and a simple model is introduced to explain the reason for the influence of released neutral gas on ion CSD. Due to the collisions between released neutral gas and ions, a significant reduction of the velocities of Tii+ occurs in the titanium hydride vacuum arc plasmas compared to the titanium vacuum arc plasmas, and the velocity of H+ is only 1.3 times higher than that of Ti2+. (C) 2011 Elsevier Ltd. All rights reserved.