1. No category

15th International Conference on RF Superconductivity, Chicago, United States
Review of RF Sample Test
Equipment and Results
Work supported by the German Doctoral Students program of the Federal Ministry of Education and Research (BMBF)
Acknowledgements: Wolfgang Weingarten and everybody from CERN BE/RF and TE/CRG
Carsten Welsch (University of Liverpool, Cockcroft Institute, Daresbury)
Ernst Haebel (CERN)
1. Illuminating a superconducting Sample by RF
1/11
3
B‫׀׀‬
TE011 mode
max
• Small samples can be exposed
to RF using a pill box cavity with
demountable endplate
• Three possible techniques
• Replacement
• Thermometry
• Calorimetric
0
Demountable
endplate
Tobias.Junginger@cern.ch
Flange
Host
cavity
1. Illuminating a superconducting Sample by RF
1/11
3
B‫׀׀‬
TE011 mode
max
• Small samples can be exposed
to RF using a pill box cavity with
demountable endplate
Bruenseraede et al (1971)
• Three possible techniques
• Replacement
• Thermometry
• Calorimetric
0
Demountable
endplate
Tobias.Junginger@cern.ch
Flange
Host
cavity
1. Illuminating a superconducting Sample by RF
1/11
3
B‫׀׀‬
TE011 mode
max
• Small samples can be exposed
to RF using a pill box cavity with
demountable endplate
• Three possible techniques
• Replacement
• Thermometry
• Calorimetric
0
THPO050
Tobias.Junginger@cern.ch
Demountable
endplate
Flange
Host
cavity
2. The Calorimetric Measurement Technique
2/11
Temperature
T (Sensor)
Bath
Temperature
PRF (Cavity)
PDC,2
PDC (Heater)
PRF
Temperature
of Interest
PDC,1
Sample
Power
time
DC on
≈60 s
PRF  PDC ,1  PDC , 2  1 2 R Surface
H
Sample
R Surface 
2 ( PDC ,1  PDC , 2 )

Sample
Tobias.Junginger@cern.ch
2
H dS
2
dS
RF on
≈40 s
2. The Calorimetric Measurement Technique
2/11
Temperature
T (Sensor)
Bath
Temperature
PRF (Cavity)
PDC,2
PDC (Heater)
PRF
Temperature
of Interest
PDC,1
Sample
Power
time
DC on
≈60 s
PRF  PDC ,1  PDC , 2  1 2 R Surface
H
2
RF on
≈40 s
dS
Sample
R Surface 
2 ( PDC ,1  PDC , 2 )

Sample
Tobias.Junginger@cern.ch
2
H dS
Direct Measurement
2. The Calorimetric Measurement Technique
2/11
Temperature
T (Sensor)
Bath
Temperature
PRF (Cavity)
PDC,2
PDC (Heater)
PRF
Temperature
of Interest
PDC,1
Sample
Power
time
DC on
≈60 s
PRF  PDC ,1  PDC , 2  1 2 R Surface
H
2
RF on
≈40 s
dS
Sample
R Surface 
2 ( PDC ,1  PDC , 2 )

Tobias.Junginger@cern.ch
2
H dS
Sample
Direct Measurement
• Measurement of transmitted power Pt
• Pt=c∫H2ds, c from computer code
2. TE011/TE012 Cavity from CEA Saclay and IPN Orsay1,2
Feedthrough + Pumps
3/11
DC Heater
Temperature
Sensors
Cavity
Sample
• TE011 (4 GHz) TE012 (5.6 GHz)
• Developed from CEA Saclay/IPN Orsay1
• Modified cavity recently comissioned2
Cavity
Sample
1 M.
Tobias.Junginger@cern.ch
2
Fouaidy, P. Bosland et al. - EPAC 2002, Paris, France
G. Martinet et al. – SRF 2009, Berlin, Germany
2. TE011/TE012 Cavity from CEA Saclay and IPN Orsay1
• Systematic sample studies
• Correlation with surface
properties
• Nb film residual surface
resistance increases with
the substrate roughness
50 μm
4 GHz
4/11
Tobias.Junginger@cern.ch
1 M.
Fouaidy, P. Bosland et al. - EPAC 2002, Paris, France
3. Sapphire loaded cavity at JLAB3,4
5/11
• Sapphire rod attached
inside the cavity lowers
resonance frequency
• 7.5 GHz for 5 cm sample
diameter
Sapphire Rod
TE011 Cavity
3 L.
Tobias.Junginger@cern.ch
4
Phillips et al. – SRF 2005, Ithaca, United States
B. Xiao et al. – Rev. Sci. Instrum. 82, 056114 (2011)
6/11
∆λ [nm]
RS [μΩ]
RS [μΩ]
3. Sapphire loaded cavity at JLAB4
Tc/T
T [K]
T [K]
• Derive material parameters from surface impedance measurements
• ∆/kTc=1.842, λ(0 K) =45.3 nm, London penetration depth=36.1 nm,
coherence length=51.3 nm, mean free path=256 nm, Rres=1.54 μΩ
for Niobium Sample
Results on MgB2: THPO048
Tobias.Junginger@cern.ch
4
B. Xiao et al. – Rev. Sci. Instrum. 82, 056114 (2011)
4. The Quadrupole Resonator at CERN
7/11
Rods
361 mm
B
max ‫׀׀‬
0
Sample, E-beam welded to cylinder
5
Tobias.Junginger@cern.ch
E. Mahner et al. -Rev. Sci. Instrum., Vol. 74, No. 7, July 2003)
Junginger et. al – SRF 2009, Berlin Germany
6T.
4. The Quadrupole Resonator at CERN
8/11
Tc=9.25 K
Bulk Niobium Sample
RRR=50
BCP (T<15°C)
1200 MHz
800 MHz
400 MHz
Tobias.Junginger@cern.ch
4. The Quadrupole Resonator at CERN
8/11
Tc=9.25 K
RS 
1200 MHz
800 MHz
400 MHz
f
3 dB BW
1200 MHz
800 MHz
400 MHz
Tobias.Junginger@cern.ch
4. The Quadrupole Resonator at CERN
R[nΩ]
Bulk Nb
f=400,800, 1200 MHz
T=2..10.5 K
Tc/T
R[nΩ]
Nb on Cu
f=400, 800, 1200 MHz
T=2..10.5 K
Tc/T
8/11
4. The Quadrupole Resonator at CERN
8/11
400MHz
100
f=400,800, 1200 MHz
T=2..10.5 K
T=2, 2.5, 3, 4, 4.5 K
f=400 MHz
80
Rs nOhm
R[nΩ]
R[nΩ]
Bulk Nb
60
40
20
Bulk Nb
0
0
10
20
30
40
50
B mT
B[mT]
Tc/T
800MHz
Nb on Cu
1400
Nb on Cu
f=400, 800, 1200 MHz
T=2..10.5 K
Rs
nOhm
R[nΩ]
R[nΩ]
R[nΩ]
1200
1000
800
f=800 MHz
T=2.1, 2.5, 2.9
3.5, 4 K
600
400
200
0
Tc/T
0
10
20
30
B mT
B[mT]
40
50
4. The Quadrupole Resonator at CERN
140
Bulk Nb
120
120
100
100
Bp [mT]
Bp[mT]
140
9/11
80
60
40
Nb on Cu
80
60
40
κ(0 K)=1.4
20
κ(0 K)=3.7
20
0
0
6
7
8
T[K]
9
6
7
8
T [K]
Solid Curve: Prediction from Vortex Line Nucleation Model
Dashed Curve: Prediction from Ginzburg Landau Model
Tobias.Junginger@cern.ch
9
4. The Quadrupole Resonator at CERN
60
10/11
Bpeak scales with f-0.46+/-0.13 in CW
50
Bp[mT]
40
400 MHz
30
20
1200 MHz
10
Bulk Nb
0
0
0.1
0.2
0.3
1-(T/Tc)2
Tobias.Junginger@cern.ch
0.4
0.5
0.6
5. Comparison of the Different Devices
11/11
TE011/012 Cavity
Sapphire loaded
Quadrupole
f [GHz]
4/5.6
7.5
0.4/0.8/1.2
Sample diameter
d [cm]
12
5
7.5
Bmax [mT]
40
14 (Amplifier Power) 60 (Quench)
Resolution at 5 mT
from minimal
detectable heating [nΩ]
1.432
1.24
0.44
2
Tobias.Junginger@cern.ch
4
G. Martinet et al. – SRF 2009, Berlin, Germany
B. Xiao et al. – Rev. Sci. Instrum. 82, 056104 (2011)