9203449 Post Because present costs of plasma enhanced chemical vapor deposition diamond films re technology is the attainment of high deposition rates of good quality material. Diamond coatings for cutting tools, heat sinks for thermal management, and free- standing thick infrared (IR) optics are a few applications in which high deposition rates are crucial. Diamond deposition processes using a high power density microwave reactor were developed in Phase I to obtain deposition rates of 15 um/hr. These rates are one order-of-magnitude larger than previously possible in similar systems operating at lower power. These Phase I results demonstrated that operation at high power densities opens a completely new operating regime for microwave based deposition reactors. In this research, an experimental program is undertaken aimed at understanding the gas phase, chemistry changes at high power densities, to develop techniques to control film morphology, and to increase the growth rates to 50 um/hr. Such understanding would lead to increased confidence on the scale-up of diamond deposition reactors as one would be able to identify which are the most important parameters which control deposition rates. ***