| L. Catani, A. Cianchi, D. Digiovenale, J. Lorkiewicz, S. Tazzari, R. Nietubyc, M. Sadowski, M. Bruchon, B. Visentin, C. Granata, R. Russo |
Niobium thin film coated copper RF cavities are an interesting alternative
to niobium bulk cavities mainly because copper is cheaper, has higher
thermal conductivity and better mechanical workability and stability than
niobium. Unfortunately the observed degradation of the sputter-coated
cavities quality factor with increasing accelerating voltage prevents their
use in future accelerators specified to work at field values higher than
15MV/m. To try and overcome this limitation we have developed an
alternative coating technique based on a cathodic arc system working
under UHV conditions. Main advantages of this technique compared to
standard sputtering are the ionized state of the evaporated material,
absence of gases to sustain the discharge, high energy of atoms reaching
the substrate surface and possibility to have high deposition rates.
Recent results on the characterization of niobium film samples produced
by UHV cathodic arc are presented, showing that the technique can
produce high quality films under different angle of deposition. |
