Cable tests at FRESCA
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Transcript of Cable tests at FRESCA
FermilabCable tests at FRESCACable tests at FRESCA
Designed to fit FRESCA collars Two cables protected by two “dummy” cables
FRESCAFeatures
G. Ambrosio, et al., “Critical Current and Instability Threshold Measurement of Nb3Sn Cables for High Field
Accelerator Magnets” IEEE Trans. on Applied Superconductivity, Vol. 15, No. 2, pp. 1545-1549, June 2005.
G. Ambrosio - Measurement of critical current and instability threshold of Rutherford-type Nb3Sn cables 2
Fermilab
Sept. 19 2005
Different cable layoutsDifferent cable layouts
PIT-Sample: (PIT strands) HT: 99h @ 675 ºC RRR: 110 Short sample Ic @ 12 T: 597 A (Extracted)
Signs of tin contamination of Cu matrix close to cable edges, after HT
MJR-Sample: (MJR confined in field region, PIT elsewhere) HT: 100h @ 210°C, 48h @ 340°C,
180h @ 650°C RRR: 9 Short sample Ic @ 12 T: 705 A (Virgin)
+ lead
- lead
9 7 6 5 2 1
10 11 13 14 17 18
+ lead
- lead
10 13 14 15 16 17 18
9 6 5 4 3 2 1
MJR PIT
FIELD
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Fermilab
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Magnetic field (T)
Que
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curr
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B - ramp UP
B - ramp DOWN
I - ramp
Iq of B-ramps < Iq of I-ramps Minimum of unstable region (~ 12 kA) in the range 1.5 – 3 T Comparison with HFDB02 (same cable, same HT)…
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Magnetic field (T)
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HFDM-02
Same instability threshold
Iq (4.3K ,10.5T)
= Iss (5.6K, 10.5T)
heat from the splices
return splice had
R = 0.85 n
Very good correlation between Very good correlation between cables and magnetscables and magnets
G. Ambrosio - Measurement of critical current and instability threshold of Rutherford-type Nb3Sn cables 4
Fermilab
Sept. 19 2005
Cable characteristicsCable characteristics
All samples were made of cables with the same characteristics of the cables used for FNAL cos-theta short model magnets:
28 strands Strand diameter: 1 mm Cable width: 14.2 mm Cable average thickness: 1.82 mm Keystone angle: 0.9 deg Cable transposition pitch: 110 mm Strand type (vendor): MJR (OST) & PIT (SMI) Insulation: ceramic or S2-glass tape + ceramic binder
Deff: 110 m
Deff: 54 m
G. Ambrosio - Measurement of critical current and instability threshold of Rutherford-type Nb3Sn cables 5
Fermilab
Sept. 19 2005
Tests also at 1.9 KTests also at 1.9 K
Same Instability threshold !
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FermilabExcellent acquisitionExcellent acquisition
MJRPIT
B = 1 T , RR= 150 A/sT = 4.3 K, I < 17000 A
1st segment: 500 mm 2.4 ms V = 208 m/s
Spike “propagation” Spike “propagation” and “coupling”and “coupling”
G. Ambrosio - Measurement of critical current and instability threshold of Rutherford-type Nb3Sn cables 7
Fermilab
Sept. 19 2005
Veryyy fast spikeVeryyy fast spike
T = 4.3 K I = 12.5 kA B = 1.8 T B-ramp-up (1T/min)
V = 875 m/s !
Strong coupling also in this case !
0.6 ms
22 mV
Sample preparationSample preparation Reaction Splices and Voltage Taps (on cable edges) Impregnation in situ Pre-stress by adding a Kapton layer after impregnation