Transcript CERN Fast Cycled Magnet demonstrator: test station, instrumentation and measurement campaign G.

CERN Fast Cycled Magnet demonstrator:
test station, instrumentation and measurement campaign
G. Willering1, M. Bajko1, F. Borgnolutti2, L. Bottura1,
V. Datskov1, G. Deferne1, J. Feuvrier1, L. Fiscarelli1,
C. Giloux1, M. Guinchard1, V. Roger1
1CERN, 2LBL
18-07-2013
MT-23, Boston, MA
4OrCB-05
Contents
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Introduction
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FCM magnet project
Test station
Instrumentation
Test conditions
Measurements
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Magnet powering
Current Cycling
Training quenches
Quenches at Short Sample limit
Temperature and losses
Mechanical measurements
FCM magnet project
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Injector upgrade scenario includes a
new PS2 (Proton-Synchrotron)
Ramp time 1.1 s, flattop 0.1 s.
Required dipole field 1.8 T
Energy consumption can be reduce by
a factor of 2 compared to a normal
conducting option
The FCM project aims to demonstrate
the feasibility of reliable, low-loss
superconducting technology.
The PS at CERN, operating since 1959
Magnet concept
2 coils of 10 windings
Central
gap
70 mm gap
Warm iron yoke
Yoke length 0.821 m
Magnetic length 0.710 m
Cross-section
Conductor
Demountable joints
Conductor specifications
Type
Nuclotron cable
ID
4 mm
OD
7.7
strands
32 Nb-Ti
Matrix
mixed Cu/Cu-Mn
Mechanics
Ni-Cr wrap
Magnetic field
Central magnetic field
Maximum conductor field
1.8 T
0.7 T
Cryogenics
Forced flow cooling though central tube by
supercritical helium at 3 B, 3 g/s at 4.5 K.
Cable soldered in Cu shoe
Two Cu parts clamped with In-foil
New test station at CERN
FCM – Summer 2012
Supercritical helium at 4.5 K, 3
Bar, mixed with warm He-gas
Temperature reach between
4.5 and 80 K forced flow
Designed for FCM and SC Link
The superconducting link aims at
connecting the LHC magnet circuits to
the power converters over a distance of
600 meter, cooled by He gas
Magnet cooling schematics
4.5 K,
2-3 B
Mixing
Chamber
300K
Cooling control:
1. Mixing supercritical Lhe of 4.5 K with Ghe of 300 K
2. For each coil a heater can increase the temperature
Temperature probes
12 CCS (Carbon Ceramic)
temperature sensors.
Good contact with the cable
& temperature stabilized
In hind-sight the main error
in enthalpy determination
came from high uncertainty
in pressure measurements
(±0.1 Bar)
CCS temperature sensor on the cable (V. Datskov, session 1PoAP-01)
Cryogenics
- Long (~ 18 m) small diameter (4 mm) tube
- Large pressure drop over the magnet resulting in a big
change in density at 3 bar at a point where the heat capacity
is at its maximum. Calorimetric measurement has a very low
resolution at this condition.
- Temperature control for low flow-rate of GHe was stable to
0.2 K
Calorimetric measurements
5.5
25
Stepwise increase of heating
power resulted in:
20
5.3
5.2
15
5.1
5
10
4.9
Heat (W)
Temperature (K)
5.4
T1 : Output coil 1
T2 : Input coil 1
Heater1
4.8
1.
2.
5
Stepwise increase in temperature
Decrease in helium flow due to
density change.
4.7
4.6
0
0
100
200
300
400
Time (s)
Major issues:
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5
3.5
2.5
4
2
3.5
1.5
3
Helium flow coil1
1
Pressure output coil1
2.5
0.5
Pressure input coil1&2
2
0
0
100
200
Time (s)
300
400
Pressure (B)
Helium flow (g/s)
-
3
4.5
Stable supply of helium
temperature, flow and pressure.
Operation in the phase transition
region of Helium: Large expansion
in a long thin tube.
Powering summary
1 quench to
Inominal = 6 kA
First powering to 6 kA, August 10th, 2012
Possible
detraining
(6.6 K) from
Imax = 7.5 kA
3 quenches to
Imax = 7.5 kA
Cycling
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One quadrant power supply:
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Ramp down speed limited by L/R of the circuit
at 3 kA/s
Ramp up at nominal 6 kA/s
Cycling tests were performed in trains of 10
minutes at about 4.8 K, 3 g/s, 3 Bar
supercritical helium cooled
Test cycle duration 3.5 s versus a nominal
cycle duration of 2.4 s
Longest series:
5h - 4650 cycles
(3.9 s/cycle aver.)
In total 20000
cycles performed
First test cycle trains, August 16th, 2012
Measurement of Tcs
≈ 0.2 K
Set stable temperature at the inlet (e.g. 7 K)
Current ramp (e.g. 1 kA/s)
Quench (e.g. 6 kA)
Hot helium expulsion
Dump (t ≈ 0.2 s, Vmax ≈ 60 V)
Quench propagation velocity
Quench propagation velocity (m/s)
45
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40
35
30
plug connection 2
25
20
coil 1
15
10
coil 2
Fresca
at 1 T
not impregnated
5
0
0
2000
4000
6000
8000
Quench current (A)
Quench propagation velocity well in
between adiabatic calculations and cable
test in FReSCa.
Rough estimates from measurements of vnzp
Length of normal zone at detection 0.1 to 0.2 m
Quench position unknown during these training
quenches
Magnetic field profile
along the conductor
Tcs results
Data from
FRESCA
cable tests
Quenches
outside the
magnet coils
• Error in temperature
0.2 K
• The behavior of the
two coils is very
similar !
Overall excellent agreement to short sample !
Ramp-rate dependence
Data from Tcs measurement at different ramp-rate
was reduced to a reference temperature of 7 K
(Iq ~ 6200 A) applying an average temperature
correction of 2300 A/K
No ramp-rate
dependence can be
observed in the
resulting data-set !
Most of the scatter can be
explained by the uncertainty on
temperature (±0.2 K in Tcs
equals± 500 A in Iquench)
±0.2 K
6200
±0.2 K
Pushing the limit
Working
point
Stable cycling at 0.5 K from the
expected cable critical current!
(2600 cycles)
T inlet
T outlet coil 1
T outlet coil 2
AC loss estimate
Low density (10 kg/m3), high
speed (13 m/s) flow
The large JT expansion
causes temperature drop
Tinlet
(K)
6.62
pinlet
(bar)
1.90±0.05
Toulet
(K)
6.29
poutlet (bar)
1.20±0.05
System oscillations (cryoplant) do not allow a
precise evaluation of the loss by calorimetry.
Error bound ± 1 W/coil
The measured AC loss for the magnet is smaller than 2 ± 2 W
Expected AC loss (based on cable measurements and field map) is
0.15 W/coil, compatible with above estimate
Pick-up coils efficiency
0.025
0.02
Coil2 - 300 A/s
Voltage (V)
0.015
Coil2 - 1000 A/s
Coil2 - 3000 A/s
0.01
Coil2 - 6000 A/s
Coil1 - 300 A/s
0.005
Coil1 - 1000 A/s
0
Coil1 - 3000 A/s
0
2
4
6
8
Coil1 - 6000 A/s
-0.005
-0.01
Current (kA)
1.6%
1.4%
Percentage of the compensated signal
compared full signal (%)
Challenge
Measure resistive voltage of a coil
Solution
Co-wind the voltage tap wire with the coil to
eliminate Vinductive
Result
Max 25 mV at 6 kA/s
Pickup coil voltage only 0.2 % of coil voltage
Saturation effect above 3 kA visible
Non-uniform field on magnet coil and pick-up coil
results in a different response
1.2%
coil 1 - 300 A/s
1.0%
Coil 2 - 300 A/s
0.8%
Coil 1 - 1000 A/s
Coil 2 - 1000 A/s
0.6%
Coil 1 - 3000 A/s
Coil 2 - 3000 A/s
0.4%
Coil 1 - 6000 A/s
0.2%
Coil 2 - 6000 A/s
0.0%
-0.2%
0
1
2
3
Current (kA)
4
5
6
Magnetic performance
Magnetic field profile
along the conductor
Measured field
Measured field
corresponds with
calculations.
load line 3000 A (units @ 17
mm)
n
bn
an
2
1.47
0.10
3
7.56
-0.02
4
0.00
0.00
5
0.03
0.00
6
0.00
0.00
7
0.00
0.00
8
0.00
0.00
9
0.00
0.00
Multipole b3 is
specifically high ->
Magnet is not yet
optimized for field
quality.
Reconstructed field
(700 mm probe)
1.20
simulation
measurements
B3D(0,0,z)/B2D(0,0)
1.00
0.80
0.60
0.40
0.20
0.00
0
250
500
z (mm)
MSC/MM Measurement Note 2012-02, by Lucio Fiscarelli
750
Mechanics
8 Tie rods, equipped with
strain gauges
8 strain gauges
measuring the bending
Mechanical measurements
Magnet supported by 8 tie-rods.
Strain between 20 and 150 μm/m.
Stable over the 20k cycles.
Mechanical measurements
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Calculated deflection up to 0.8 mm at 6 kA
Measured strain on bending parts 70 μm/m
Strain about linear to I2
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Mechanics well-understood and far from its
limits.
Courtesy:
Sergio dos Santos, Michael Guinchard, Giuseppe Foffano
EDMS 1173289
Conclusions and perspectives (1)
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To the extent that we could probe the FCM magnet
performance, the concept is suitable for a fast
cycled injector magnet !
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No issue of performance (we had 1 quench to nominal
field, and we think we understand why)
Very stable operation beyond the performance envelope
(in 3 quenches, up to 50 % Lorentz force in excess of the
design value, estimated > 0.5 mm coil movement)
20 kCycles close to nominal operation conditions, no
spurious quenches, no observed degradation
Losses in the coil below measurable level of 4 W/m of
magnet
Conclusions and perspectives (2)
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The magnet is not yet optimized for magnetic field quality
and the multipole b3 error is still too high.
The mechanics of the magnet are as designed.
ReBCO
CORC
Nb-Ti
Nuclotron
HTS may be
feasible?
Invited talk 2OrBB-01by D.C. van der Laan,
High-temperature superconducting Conductor on Round Core magnet cables
operated at high current ramp rates in background fields of up to 19 T
Thank you!
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Project follow-up
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Concept and design
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B. Auchmann, G. Foffano, M. Karppinen, G. Kirby, R. Maccaferri, C.
Maglioni, V. Maire, V. Parma, T. Renaglia, G. de Rijk, L. Rossi, T.
Salmi (LBNL), W. Scandale, D. Tommasini
Procurement and manufacturing
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F. Borgnolutti (LBNL), L. Bottura
A. Bonasia, M. Bruyas, S. Clement, W. Gaertner (BNG), R. Gauthier,
J.M Gomes de Faria, C. Lopez, L. Oberli, G. Sikler (BNG), the CERN
Central Workshop
Instrumentation and tests
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M. Bajko, V. Datskov, G. Deferne, L. Fiscarelli, M. Gateau, M.
Guinchard, S. le Naour, G. Peiro, V. Roger, D. Richter, G. Willering
Backup slides
Strand and cable
mixed matrix
Cu/CuMn/NbTi
wire (ALSTOM)
CACC: Cablearound-conduit
conductor
(BNG-Zeitz)
Cu-Ni pipe
Nb-Ti strands
Ni-Cr wrap
Diameter
(mm)
0.6
Twist pitch
(mm)
10
Cu:CuMn:NbTi (-)
2.39:0.47:1
RRR
(-)
110
Jc(5 T, 4.2 K)
(A/mm2) 1875-2015
N-index
(-)
10-25
Strands
(-)
32
Twist pitch
(mm)
86
ID
(mm)
4
OD
(mm)
7.74
Glass-tape
Supercritical helium
force-flow cooling
Magnet parameters