Total and Differential Sputter Yields of Boron Nitride Measured by Quartz Crystal Microbalance and Weight Loss (Preprint)

We present results of differential sputter yield measurements of HBC and HBR grades of boron nitride due to bombardment by xenon ions. Total sputter yield measurements are made using a weight loss approach. Differential sputter yield measurements (of condensable components) are made using a quartz crystal microbalance (QCM). The QCM measurement allows full angular resolution, i.e. differential sputtering yield measurements are measured as a function of both polar angle and azimuthal angle. Measured profiles are presented for 100, 250, 350 and 500 eV Xe+ bombardment at 0-degree, 15-degree, 30-degree, and 45-degree angles of incidence. We fit the measured profiles with Modified Zhang expressions using two free parameters: the total sputter yield, Y, and characteristic energy E*. Sputtering of HBC versus HBR grades of BN is compared, as is results of sputter measurements from the weight loss versus QCM approaches. Finally, effects of sample moisture absorption are considered. Submitted for presentation at the International Electric Propulsion Conference (30th), held in Florence, Italy, on 17-20 Sep 2007. Paper no. IEPC-2007-074. Prepared in collaboration with Colorado State University, Fort Collins, CO.