Modeling and simulation of the chemical etching process in niobium cavities

Qin Xue, University of Nevada, Las Vegas


Niobium cavities are important parts of the integrated superconducting (SC) high-power linear accelerator (LINAC) that can accelerate over 100 mA of protons to several GeV. Surface finish of the niobium cavity plays an important role of achieving the best performance of niobium cavity. The chemical etching techniques have been widely used; Chemical etching of the inner surface of the cavity is achieved by circulating acid through it. The acid interacts with the surface and eliminates imperfections. During the etching process, a pipe with baffle is inserted within the cavity to direct the flow along the surfaces; A 2-D, axisymmetric, steady state, incompressible fluid flow model is developed to simulate the chemical etching process. The FEMLAB code based on the finite-element method is used; Two benchmark cases were used to check the feasibility and accuracy of FEMLAB. Plausible results were satisfied when the benchmark cases were compared with the simulations from FEMLAB software.