Partial least squares for mass spectral analysis of H2 and D2 plasma scrambling products

In this paper the application of the partial least squares (PLS) method to resolve the mass spectrum of hydrogen and deuterium scrambling in a fast flow plasma reactor is reported. Calibration was performed by using a mixture of hydrogen, deuterium, and deuterium hydride, and the model predictions were validated against the experimental results. The calibration model was then extended to actual plasma scrambling experiments, and the effects of power, residence time, pressure, and inlet mole fraction of H2 and D2 were investigated. While residence time and applied power were found to have no significant effect on the deuterium hydride concentration within the operating regime tested here, changes in pressure and inlet mole fraction affected the conversion of H2 and D2 to HD, as expected. The results from this study can be applied toward a more rational design of fast flow plasma or downstream etching reactors used in advanced materials fabrication