Paper | Title | Page |
---|
TUP38 | A Novel Sputtered Medium Beta Cavity for ALPI | 216 |
| - S. Stark, A. M. Porcellato, A. Palmieri, V. Palmieri, P. Favaron, E. Bissiato, F. Stivanello, F. Chiurlotto, G. Dona, D. Giora, M. DeLazzari
INFN-LNL
| |
| The installed medium beta ALPI cavities were produced
by Nb sputtering on old Cu substrates, which were
originally Pb plated. The cavity renew could practically
double the previous average operational accelerating field
but the performance obtained in high beta resonators, whose
Cu bases were designed to be sputtered, could not be
reached [1, 2]. To overcome this performance gap, we
designed, built and tested a novel medium beta cavity, which
has the shorting plate rounded as in high beta cavities, while
the beam ports are obtained by plastic deformation of the
outer conductor instead of being brazed to the cavity body
as in the previous medium beta QWRs. The paper describes
cavity design, substrate construction technology, surface
treatments and results of the first resonator cold test. | |
WE202 | Different sputtering configurations for coating 1.5 GHZ copper cavities | 384 |
| - G. Lanza, V. Palmieri, N. Patron, C. Pira, S. Stark
Laboratori Nazionali di Legnaro, STITUTO NAZIONALE DI FISICA NUCLEARE - E. Bemporad, F. Carassiti, M. Sebastiani
University of Rome - H. Padamsee
Cornell University
| |
| In the framework of the attempts to densify the
sputtering discharge, two different sputtering
configuration are reported:
- a mixed bias magnetron sputtering technique has been
explored for depositing niobium into 1,5 GHz copper
cavities. Results are presented and compared with the
standard CERN technique. The superconducting and high
resolution morphological and mechanical properties of
niobium films sputtered onto the inner walls of
electropolished cavities, have been studied as a function
of the deposition technique. Even if niobium films coated
with the bias technique show a higher density and Tc
similar to the other films, they don't present higher RRR
values. Preliminary RF tests are presented.
- post Magnetron sputtering in thermoelectric emission
regime have been investigated and is under improvement
in order to increase the RRR values of sputtered Nb:
superconducting and structural properties of the obtained
films have been measured to check the technique
capability and its possible application for coating cavities. | |
 | Slides(PDF) | |
WE203 | The Progress on Nb3Sn and V3Si | 392 |
| - 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. | |
 | Slides(PDF) | |
WE204 | Application of plasma cleaning to cavities processing | 400 |
| - N. Patron, S. Deambrosis, S. Stark, V. Palmieri
INFN-LNL - M. Baecker
Fachhochschule Aachen - L. Phillips
TJLNAF
| |
| very versatile and inexpensive technique used in a variety
of surface processes such as dry etching, surface
treatments and modification of surface wettability. After
initial studies on different configurations of RF, MW and
DC atmospheric plasma devices we have analyzed the
modification of water wettability induced by helium
atmospheric plasma.
We have applied a resonance atmospheric plasma
cleaning step to further clean a 6 GHz Nb seamless cavity
observing an increment in the Q0 from 7x1e6 to 2x1e7 in
only 30 minutes of process. The increased wettability due
to the plasma action on the inner cavity surface has
proved to enhance the beneficial action of water rinsing
pushing the Q0 value further up close to 3x1e7. | |
 | Slides(PDF) | |
TH101 | Review of the Thin Film Workshop |
| - V. Palmieri
INFN-LNL/Padua University
| |
| The present superconducting RF accelerator technology is based on solid Niobium. Thin film technology offers considerable savings in fabrication costs and what is even more important it opens the way to use alternative superconducting material with enhanced intrinsic properties such as critical temperature and critical field. Intensive and coordinated R&D effort is of decisive importance to explore the realization of this promise and to make the benefits available to the next generation of SC accelerators. The aim of this workshop is to bundle the expertise from industry, research laboratories and accelerator technology in order to launch a new initiative in thin film and innovative related technology for superconducting RF accelerator application. The immediate infusion of industrial expertise and specialists from cross-disciplinary fields, as for instance superconductivity, plasma physics, material science, nanotechnology and rf engineering, is of crucial importance. | |
 | Slides(PDF) | |