Key Words: Ion assisted deposition Optical coatings Moisture permeation TiO2

A cold cathode ion source is a differentially pumped device with one end of the plasma chamber open to the vacuum environment of the coating system. Therefore, the operational parameters of the ion source and the quality of the films made using the ion source are affected by the parameters controlling the vacuum level. These include the pumping speed of the chamber, any leaks that may be present and the controlled flow of any gases into the chamber. The pumping speed of the chambers is the major factor not directly controllable that affects the quality of the films that can be made using the ion source. In this study we will present data on the operational parameters of a cold cathode ion source at different pumping speeds and the subsequent effect on the optical properties of TiO2 films