AA Rossi S Stark R K Thakur N Visonà and V Palmieri ISTITUTO NAZIONALE DI FISICA NUCLEARE Legnaro National Laboratories and University of Padua 5th Workshop on Thin ID: 713831
Download Presentation The PPT/PDF document "PURIFICATION OF 6 GHZ RESONATORS AT EXTR..." is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
PURIFICATION OF 6 GHZ RESONATORS AT EXTREMELY HIGH TEMPERATURES AT ATMOSPHERIC PRESSURE
A.A. Rossi, S. Stark, R. K. Thakur, N. Visonà and V. PalmieriISTITUTO NAZIONALE DI FISICA NUCLEARELegnaro National Laboratoriesand University of Padua
5th Workshop on
Thin
films
and New
Ideas
for
pushing
the
limit
of SRF,
July
18--20, 2012,
Jlab
, Newport News VASlide2
There is
a plenty of incredible games to play just close to the melting point of Niobium ….Slide3
6
Ghz @4,2KBulk Nb
BCS
NBSlide4
Nb
5N6; Nb4N3 d-NbN 1-x; h-NbN
(hexagonal);
d
’
-
NbN
(hexagonal);
b
-Nb
2N (hexagonal); g-Nb4N3-x a-Nb (N) (bcc solid solution) NiobiumSlide5
1 – 3 mm of
nitridation in a couple of minutesSlide6
SC 1
SC 2
a
l
1
l
2
Vacuum
H
z
Niobium
OverlayerSlide7
SC 1
SC 2
a
l
1
l
2
Vacuum
H
z
For a “2 Superconductor system”
l
1
/a
Q
2
Q
1
D
QSlide8
SC 1
SC 2
a
l
1
l
2
Vacuum
H
z
Q
2
Q
1
l
1
/a
An hypotesis:
Gap and Penetration depth depends on magnetic fieldSlide9Slide10
Q2
Q1
b
5
10
15
20
25
30
35
40
45
50
Q
TotSlide11
+
=
Q2
Q
2
e
-k2b
Q1
b
Why Q increases with field?
The more
l
1 increases vs field
The more SC2 ( low losses) is involvedSlide12
+
=
b
Q1
Q2
a/
l
0
O
0.1
1
10
The ticker is SC 1, the smoother is the Q-rise Slide13
One
of our thermal diffused NbNSlide14
Cu sputtering
into Nb 6GHz cavityCathodeCavitySlide15
Sputtering
of a Cu overlayer onto a Nb 6GHz cavity Slide16Slide17Slide18Slide19Slide20
Didn’t
you notice anything strange?Slide21
Sputtering
of a Cu overlayer onto a Nb 6GHz cavity Slide22Slide23
Sketch of the furnace
Work head
15 KW
Power
supply
Pyrometer
Gas
bottle
Low overpressure
(250-3000)ºC
Exhaust gases
Coil
Input gas
Cavity or SampleSlide24Slide25
We took
a contaminated cavity, exposed to air for years and with a Q around 1e+6We treated at 2000°C for only a few
tenths
of
seconds
at
atmospheric
pressure
without
using vacuum The Q at 1,8 K jumped up for 3 orders of magnitedeSlide26Slide27Slide28Slide29
We did
not act onto RRes.We acted onto RBCS!!!Slide30
CONCLUSIONS
A new treatment of the of time of the minute, at temperatures over 2000°C, without using vacuum, allows
the
recovery
of performances of 6 GHz
cavitiesSlide31
THANK YOU