INTERACTION BETWEEN PLASMA AND WATER MICRO-DROPLETS An experiment has been developed enabling quantitative study of plasma- liquid interactions using a single micro-droplet in a diffuse RF glow discharge. Decrease of droplet radius can be explained by a standard aerosol evaporation model with the gas temperature of the plasma as input. The transport of OH radicals from gas to liquid phase is assessed by decomposition of formate in the droplet. A 1-D OH diffusion model agrees well with experimental results. Experimental setup including droplet collection system for ex situ droplet analysis. Droplet diameter and formate density vs residence time. HIGHLIGHT DOE Plasma Science Center Control of Plasma Kinetics September 2018 1

ANALYTICAL MODEL OF VIBRATIONAL KINETICS IN HYDROGEN Negative Hydrogen Ion Source (NHIS) are being developed for accelerators and plasma heating (e.g., ITER) An analytical model of has been developed to predict the vibrational distribution function (VDF) of H2 in low pressure NHIS. The Global Model for Negative Hydrogen Ion Sources (GMNHIS) was employed to evaluate the reactions contributing to the creation and loss of vibrational states in detail. The VDF was found to be weakly dependent on the averaged repopulation probability of vibrational states after wall collisions. Vibrational Distribution Function in hydrogen. Comparison of global numerical (GMNHIS) and analytical models. DOE Plasma Science Center Control of Plasma Kinetics HIGHLIGHT September 2018 2