Generating laminar, reproducible flow rates by modeling transport properties of the hydrofluoric acid-sulfuric acid mixture
The Thomas Jefferson National Accelerator Facility (Jefferson Lab) aims to maximize the performance of particle accelerators by perfecting superconducting radiofrequency (SRF) technology. Smooth niobium interior cavities ensure that electron beams do not suffer from deflections. For this reason, electropolishing (EP) is used to rid the surface of existing defects. Previous studies have shown the dependence of EP performance on variables such as temperature. Yet, the effects of some other variables, such as those of surface flow rate, remain unmeasured. The purpose of this project was to design, build and test a controlledflow apparatus to examine the effect of surface flow rates on the quality of EP. Proper apparatus dimensions were calculated using CFdesign simulation software. The built model demonstrated that simulated dimensions were accurate. The desired flow rates were successfully obtained. Because nine-cell niobium cavities cost over $50000, it is costprohibitive to conduct surface flow rate experiments directly on these cavities. The controlledflow apparatus serves as a cost-efficient alternative. Additionally, it avoids many design issues that would have been encountered had the experiments taken place inside closed cavities. Hence, the successful construction of the controlled-flow apparatus is vital to future studies on EP.
