| | At present, electropolishing (EP) is considered a
key technology in fabricating Nb SRF cavities performing
at or above 35 MV/m. Nevertheless buffer chemical
polishing (BCP) is still a cheaper, simpler and effective
processing technique for single grain high gradient and
polycrystalline lower gradient cavities. BCP has also been
adopted to chemically process the third harmonic 3.9 GHz
cavities, operating at or above 14 MV/m, being fabricated
at Fermilab [1]. The dimensions and the shape of these
cavities pose the problem of uneven material removal
between iris and equator of the cells. This paper describes
the thermal-fluid finite element model adopted to simulate
the process, the experimental flow visualization tests
performed to verify the simulation and a novel device
fabricated to solve the problem. | |