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Cable tests at FRESCA

Cable tests at FRESCA. Designed to fit FRESCA collars Two cables protected by two “dummy” cables. FRESCA Features.

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Cable tests at FRESCA

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  1. Cable tests at FRESCA • Designed to fit FRESCA collars • Two cables protected by two “dummy” cables FRESCA Features 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.

  2. 9 7 6 5 2 1 MJR PIT + lead 9 6 5 4 3 2 1 + lead - lead 10 11 13 14 17 18 - lead 10 13 14 15 16 17 18 Different 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) FIELD G. Ambrosio - Measurement of critical current and instability threshold of Rutherford-type Nb3Sn cables

  3. 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)… Same instability threshold Very good correlation between cables and magnets Iq (4.3K ,10.5T) = Iss (5.6K, 10.5T) heat from the splices return splice had R = 0.85 nW

  4. Cable 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 mm Deff: 54 mm G. Ambrosio - Measurement of critical current and instability threshold of Rutherford-type Nb3Sn cables

  5. Same Instability threshold ! Tests also at 1.9 K G. Ambrosio - Measurement of critical current and instability threshold of Rutherford-type Nb3Sn cables

  6. MJR PIT Excellent acquisition B = 1 T , RR= 150 A/s T = 4.3 K, I < 17000 A • 1st segment: • 500 mm • 2.4 ms •  V = 208 m/s Spike “propagation” and “coupling”

  7. 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 ! Veryyy fast spike 22 mV 0.6 ms G. Ambrosio - Measurement of critical current and instability threshold of Rutherford-type Nb3Sn cables

  8. Sample preparation • Reaction • Splices and Voltage Taps (on cable edges) • Impregnation in situ • Pre-stress by adding a Kapton layer after impregnation

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