This study characterizes ion behavior of cathodic arc plasmas which have been used for the TiN coating. The ion currents are measured using a plane probe. The probe plane is vertical and parallel to the arc axis. Spectral intensities of Ti+and Ti++ions are also measured as a function of pressure (0.01–30 Pa). As a result of these measurements, it was found that at pressures below 0.1 Pa, the predominant ions in the plasma are Ti++which have a tendency to be directional or to have a beam component, whereas at pressures above 0.1 Pa, mainly Ti+ions of random motion are present. ©1995 American Institute of Physics.