1. Overview of the Fast Cycled Magnet (FCM) Demonstrator Program at CERN
B. Auchmann, M. Bajko, A. Bonasia, F. Borgnolutti (LBNL), L. Bottura, M. Bruyas,
S. Clement, V. Datskov, G. Deferne, L. Fiscarelli, G. Foffano, W. Gaertner (BNG),
M. Gateau, R. Gauthier, J.M Gomes de Faria, M. Guinchard, M. Karppinen, G. Kirby,
C. Lopez, R. Maccaferri, C. Maglioni, V. Maire, S. le Naour, L. Oberli, V. Parma, G. Peiro, T. Renaglia, D. Richter, G. de Rijk, V. Roger, L. Rossi, T. Salmi (LBNL), W. Scandale,
G. Sikler (BNG),D. Tommasini, G. Willering, the CERN Central Workshop
HP-PS meeting, 6 March 2013

2. Outline Project aim, Genesis (and Revelations)
Short re-cap on magnet design and construction
Main test highlights
Conclusions and perspectives

3. Outline Project aim, Genesis (and Revelations)
Short re-cap on magnet design and construction
Main test highlights
Conclusions and perspectives

4. Mission statement
Resistive magnets are used in the majority of accelerator centers, and especially in the cycled injector complexes
Operation cost is proportional to electricity consumption, which is of concern at long term (cost and availability)
The PS at CERN, operating since 1959
Can we improve energy efficiency, by using superconducting magnets in the range of 2 T, ramped to flat-top in (typically) 1 s or less, and suitable for reliable operation over long-term (108 cycles) ?

5. A (f)lower-power R&D dipole
Optimized resistive
dipole
Superconducting iron-dominated
dipole
iron
coil
Iron weight [tons/dipole] 15
Peak voltage [V/dipole] 41
Resistive power [W/dipole]
27000
Iron weight [tons/dipole] 10
Peak voltage [V/dipole] 34
Average AC loss power [W/dipole]
1.3
L. Bottura, R. Maccaferri, C. Maglioni, V. Parma, L. Rossi, G. de Rijk,
W. Scandale, Conceptual Design of Superferric Magnets for PS2, CERN Internal Report, EDMS
CLAIM: Same free bore, same performance, but the SC magnet design has the potential for cutting the total power consumption by a factor 2

6. Project timeline
CERN DG White Paper launches a study of the PS upgrade (PS2)
Scientific Activities and Budget Estimates for 2007 and Provisional Projections for the Years and Perspectives for Long-Term, “White Paper”, 5 October 2006.
June 28th, 2006 – proposal of a SC magnet R&D as an option for the PS upgrade
PROPOSAL OF A R&D PROGRAM ON FAST CYCLED SUPERCONDUCTING MAGNETS, prepared by L. Bottura, AT-MTM, June 28, 2007
June 2007 – R&D started with a budget of 1.5 MCHF and 7 FTE
– strand and cable procurement and test, magnet design and associated R&D
Strand and Cable R&D for Fast Cycled Magnets at CERN, A. Bonasia, et al., IEEE Trans. Appl. Sup., 21(3), , 2011
– magnet and test station construction
Construction of the CERN Fast Cycled Superconducting Dipole Magnet Prototype, B. Auchmann, et al., IEEE Trans. Appl. Sup., 22 (3), , 2012
2012 – magnet test

7. Cost and manpower plan

8. Outline Project aim, genesis, and revelations
Short re-cap on magnet design and construction
Main test highlights
Conclusions and perspectives

9. Magnet design concept Advantages Disadvantages
Warm iron to avoid large cryogenic load
Access to beam pipe
Force-flow cooled, vacuum impregnated superconducting coil is mechanically solid
Coil is placed in the shadow of the iron
lower beam loss
lower field and AC loss
iron
coil
Disadvantages
Limited space for thermal screen and vacuum vessel (cryostat)
Difficult to support EM forces

10. Magnetic design Coil field 1 T 0 T inlet outlet Current (kA) B (T)
0.45
0.16
5.8
1.72
By courtesy of F. Borgnolutti and B. Auchmann

11. Field generated

12. Magnet construction Vacuum impregnation
Coil wound with glass-tape insulated cable plus ground wrap
Instrumented ends
0.5 mm Si-steel
Warm, laminated yoke
NbTi superconducting cable
Cryostated coil assembly with intercoil structure and thermal shields
Nuclotron cable

13. Strand and cable Supercritical helium force-flow cooling Diameter (mm)
0.6
Twist pitch 10
Cu:CuMn:NbTi
(-)
2.39:0.47:1
RRR
110
Jc(5 T, 4.2 K)
(A/mm2)
N-index
10-25
mixed matrix Cu/CuMn/NbTi wire (ALSTOM)
CACC: Cable-around-conduit conductor (BNG-Zeitz)
Strands
(-) 32
Twist pitch
(mm) 86 ID 4 OD
7.74
Cu-Ni pipe
Nb-Ti strands
Ni-Cr wrap
Glass-tape
Supercritical helium force-flow cooling

14. FCM demonstrator

15. FCM performance summary
Injection field
(T)
0.14
Injection current
(A)
500
Flat-top field
1.8
Flat-top current
5800
Ramp time
(s)
1.1
Field ramp-rate
(T/s)
1.5
Current ramp-rate
(A/s)
4800
Good field region
(mm2)
42 x 30
Magnet gap
(mm) 70
Inductance
(mH)
AC loss
(W/m)
< 5

16. Outline
Project aim, Genesis (and Revelations)
Short re-cap on magnet design and construction
Main test highlights
Conclusions and perspectives
NOTE: the construction of the test station has been an integral part of the project

17. 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

18. Measurement of Tcs 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
≈ 0.2 K
Dump (t ≈ 0.2 s, Vmax ≈ 60 V)

19. Overall excellent agreement to short sample !
Tcs results
Data from FRESCA cable tests
The behavior of the two coils is very similar !
Quenches outside the magnet coils
Overall excellent agreement to short sample !

20. Cycling
One quadrant power supply: ramp-up at nominal 6 kA/s, ramp-down limited by R/L of the circuit at 3 kA/s
Cycling tests were performed in trains of 10 minutes at about 4.8 K, 3 g/s, 3 bar supercritical helium cooling
Test cycle duration 3.5 s versus a nominal cycle duration of 2.4 s
First test cycle trains, August 16th, 2012
Longest series:
5h cycles
(3.9 s/cycle aver.)
In total cycles performed

21. Ramp-rate dependence
Data from Tcs measurement at different ramp-rate was reduced to a reference temperature of 7 K 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)

22. 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

23. 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
6.29
poutlet
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

24. Magnetic performance Measured field corresponds with calculations.
Multipole b3 is specifically high -> Magnet is not yet optimized for field quality.
Magnetic field profile along the conductor
load line 3000 A 17 mm) n bn an 2
1.47
0.10 3
7.56
-0.02 4
0.00 5
0.03 6 7 8 9
Measured field (700 mm probe)
Reconstructed field
MSC/MM Measurement Note , by Lucio Fiscarelli

25. Mechanical measurements
Calculated strain
75 – 105 μm/m
Calculated deflection up to 0.8 mm at 6 kA
Measured strain on bending parts 70 μm/m
Strain about linear to I2
Mechanics well-understood and far from its limits.
Courtesy:
Sergio dos Santos, Michael Guinchard, Giuseppe Foffano
EDMS

26. Outline Project aim, Genesis (and Revelations)
Short re-cap on magnet design and construction
Main test highlights
Conclusions and perspectives

27. Conclusions and perspectives
To the extent that we could probe the FCM magnet performance, the concept is suitable for a fast cycled injector magnet !
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

28. Conclusions and perspectives
This was possible with a relatively easy NbTi cable, and some careful engineering…
… just imagine what HTS could bring in terms of ease (cryostat design) and efficiency (cryogenics) !

29. The team Project follow-up Concept and design
F. Borgnolutti (LBNL), L. Bottura
Concept and design
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
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
M. Bajko, V. Benda, V. Datskov, G. Deferne, L. Fiscarelli, M. Gateau, M. Guinchard, S. le Naour, G. Peiro, V. Roger, D. Richter, U. Wagner, G. Willering

30. backups

31. PS2: Magnet Requirements
Magnet design by courtesy of Th. Zickler, CERN
The location of the new PS2
PS2 will be an accelerator with a length of ≈ 1.3 km
Injection at 3.5 GeV
Extraction at 50 GeV
200 dipoles
Nominal field: 1.8 T
Ramp-rate: 1.5 T/s
Magnet mass: ≈15 tons
120 quadrupoles
Nominal gradient 16 T/m
Ramp-rate: 13 T/ms
Magnet mass: ≈4.5 tons
Average electric power ≈ 15 MW
The magnets require ≈ 7.5 MW, i.e. about 50 % of the total consumption
Modest requirements
dipole
quadrupole

32. FCM cross section

33. Magnet schematics He outlet coil 1 He inlet coil connection He outlet
Feed-box
Interconnect
FCM magnet

34. Coil support structure

35. Coils installation

36. Detail of interconnect region

37. Thermal screens

38. Cryostat assembly

39. Assembly in the yoke halves

40. Completed magnet