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

3

Fermilab

0

5000

10000

15000

20000

25000

0 2 4 6 8 10

Magnetic field (T)

Que

nch

curr

ent (

A)

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)…

0

5000

10000

15000

20000

25000

0 2 4 6 8 10

Magnetic field (T)

Que

nch

curr

ent (

A)

B - ramp UP

B - ramp DOWN

I - ramp

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 !

6

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