| | - S. M. Deambrosis, N. Patron, A. Rossi, V. Palmieri
INFN-LNL/Padua University - G. Keppel, N. Pretto, V. Rampazzo, S. Stark, F. Stivanello
INFN-LNL - R. G. Sharma
Inter-University Accelerator Centre
| |
| | In the framework of the research for a valid alternative
to Nb for RF applications, Nb3Sn and V3Si have been
investigated at LNL.
The chosen technique to obtain Nb3Sn is based on
the molten Tin diffusion method and it has been
progressively modified to improve the samples
superconducting properties (Tc and Delta Tc) and to
eliminate Sn traces on the Nb3Sn surface. Our "Hybrid
process" seems to be the most promising (Tc = 16,8 K
and Delta Tc = 0,16 K, no residual Sn traces on the sample
surface, no Sn rich phases).
The present point is to test the obtained material RF
properties: the best recipe used for samples has been
applied to coat a 6 GHz Nb cavity.
At the same time we are going to study different
techniques to achieve Nb3Sn good superconducting
cavities.
One of them is the so called mechanical plating.
Secondly we are going to study the multilayer
technique: the first attempt gave a superconducting
deposition with Tc = 17,9 K and Delta Tc =.0,02 (four
contacts measurement).
The V3Si intermetallic compound has been obtained
using the thermal diffusion of Silicon into Vanadium:
bulk V is heat treated in a SiH4 atmosphere for several
hours and then annealed in vacuum. The samples
superconducting properties are encouraging
(Tc ~= 15,5 K and Delta Tc ~= 0,2 K).
To check the material RF performances we prepared a
V3Si 6 GHz cavity (sylanized for 4h at 850 degree C with
p(SiH4) = 5x10-3 mbar): it has been measured several
times after a heating treatment in vacuum progressively
longer (6h, 12h, 36h, 84h at 850 degree C).
At the moment, we are trying to use plasma during the
silanization process to avoid the hydrogen presence
into the growing films. The first V3Si coating grown
has Tc = 15,7 K and Delta Tc = 0,22 K: this result is already
comparable to what we had with the "traditional"
technique. | |
