1. Quench protection and wire properties_Introduction E. Floch.GSI. Intas_wire_19Fe09 - Strands with a Cu matrix - Resistivity of bulk CuMn - Examples of cables for SIS100 dipoles (1 and 2 layers, Cu and CuMn) - Increase of the linear resistance and hotspot temperature with using CuMn - Possible strand specification for the SIS300 dipole - Cable linear resistance as a function of  =(Cu+CuMn)/NbTi, CuMn/Cu, d s, RRR Cu,  CuMn - Minimum values of I c and J cNbTi (influence on temperature margin) - Possible templates for strand specification - Proposed measurement during strand series production - Quench calculations for the SIS100 single layer dipole (Cu and CuMn inter-filamentary matrix)

2. Strands with a Cu matrix E. Floch.GSI. Intas_wire_19Fe09 - For the first 100 LHC dipoles: 130 < RRR Cu < 280 with an average of 210 (more than 200 measurements) - LHC specification RRR Cu > 70 (probably copied from SSC or RHIC wire specifications) - Proposed FAIR wire specification: 100 < RRR Cu < 280 - The highest hot spot temperature (T m ) is reached for: RRR Cu_min when using dump resistors (SIS100 dipoles, quadrupoles, SIS300 quadrupoles) RRR Cu_max when using dump resistors + quench heaters and cold or warm bypasses (SIS300 dipoles) - Computations done for the SIS100 2 layer dipole: d s = strand diameter (mm)0.5080.492  = Cu/NbTi 1.5 1.3 RRR Cu 280 100 Tm_5.41E6A2.s (K)196255297450 Tm_7.32E6A2.s (K)450620745>900 - RRR Cu, d s and  very strongly influence T m, - the variations of these 3 parameters must be specified and measured on each spool piece during series production - the SIS100 quench protection scheme with resistors must be defined for the minimum values of RRR Cu, d s and 

3. Resistivity of bulk CuMn  0.5%wt E. Floch.GSI. Intas_wire_19Fe09  CuMn0.5%wt_bulk ( .m) measured by coldwarmRRR Hem.Kanithi@outokumpu.com2.135 10 -8 at 4 K3.60 10 -8 at 295 K1.69 Bochvar after cold drawing 1.62 10 -8 at 4 K3.39 10 -8 at 295 K2.09 IEEE Trans. On Mag., Vol24, N°2, pp1145-1148, March 1988. 1.5 10 -8 at cold IEEE Trans. on Applied Sup. Vol3, N°1, p 859, 1993 2.5 10 -8 at 12 K Given by Luvata for the SIS300 dipole strand 2.135 0 -8 at 10 K3.6 0 -8 at 295 K1.69 proposal for the FAIR magnets 1.6 10 -8   1.9 10 -8 3.3 10 -8   3.6 10 -8 Resistivities of CuMn  0.5%wt found in the literature - The resistivity will depend on the % of Mn which could change during series production - Proposal : measurement of  CuMn0.5%wt_bulk at 4, 77 and 300 K on each billet during series production  = (Cu+CuMn)/NbTi is no more sufficient to have the different material cross-sections proposal : give  and CuMn/(NbTi+Cu+CuMn) or CuMn/(Cu+CuMn) or CuMn/Cu

4. SIS100 cables ( single or 2 layer dipoles, Cu and CuMn inter-filamentary matrix ) E. Floch.GSI. Intas_wire_19Fe09 curved dipole type C2LD CSLD- 8b n° of layers2211 I (A)6500 12746 inner diameter CuNi tube (mm) 444.7 n° of strands31 23 strand diameter (mm)0.5 0.8  = (Cu+CuMn) / NbTi 1.38 1.5 Inter-filamentary matrixCuCuMnCuCuMn n° of filaments18144 d f : filament diameter (micron)2.41 3.76 s/d f 0.1 s: inter-filamentary spacing (micron) 0.241 0.376  CuMn_IF_12K (ohm.m) 1.89E-08 1.79E- 08  CuMn_IF_295K (ohm.m) 3.66E-08 3.56E- 08 A CuMn (mm2)00.850.001.55 A Cu (mm2)3.532.676.945.39 A CuMn /A _all_strands (%)014.040.013.4

5. SIS100 cable linear resistance and Miits curves E. Floch.GSI. Intas_wire_19Fe09 CL2D: 2 layer dipole CS LD-8b: single layer dipole For the 2 layer dipole, T m increases from 300 to 500 K for Miits = 6 MA2.s when the inter- filamentary matrix uses CuMn

6. Current dumping for SIS100 dipoles E. Floch.GSI. Intas_wire_19Fe09 - The current is dumped with a time constant = L string / R d (R d : total dump resistance) - The maximum coil to ground voltage (V cgm ) occurs when one dump resistor fails to open Curved dipole version2 layer1 layer I (A)6500 12746 Inter-filamentary matrixCuCuMnCuCuMn  = (Cu+CuMn) / NbTi 1.38 1.5 strand diameter (mm)0.5 0.8 Mitts  ',tf,  = Miits 350K (1E6A 2.s)5.544.4617.6114.44  (s) 0.1740.1390.1440.125 V cgm (V)1643206010261185 - Computations were done with  average and d s_average (should be redone with  min and d s_min ) - Using CuMn forces to dump the current faster which leads to higher maximum coil to ground voltages (V cgm ) - Single layer dipole is much easier to protect than the 2 layer dipole

7. SIS300 cable with CuMn inter-filamentary matrix E. Floch.GSI. Intas_wire_19Fe09 specified inSep_2007FDR / Nov_2008FDR / Nov_2008..used in quench calculations1st generation2nd generation wire diam (mm)0.8250.825 ± 0.003 (Cu+CuMn)/NbTi1.61.56+/-0.1 filament diam. (micron)2.53.52.5 %_NbTi38.539 %_CuMn_0.5%wt17.617.124.7 %_Cu43.9 36.3 n° of strands36 Transposition pitch (mm) 100  5 stainless steel core 316L13mm*25 micron RRR_Cu>70 Cable specification established by INFN for the 4.5 T SIS300 curved dipole RRR_Cu100200300 RRR_cable87172257 For the specification of 2007: - For a Cu matrix, the RRRCu measurement is sufficient - When using CuMn, the wire producer has to give rl _strand at 10 and 300 K (in ohm/m)

8. Linear resistance of a cable with CuMn E. Floch.GSI. Intas_wire_19Fe09 - The billet is designed to achieve the average value:  av = (Cu+CuMn)/NbTi and the corresponding proportions p Cub = A Cu /A, p CuMnb = A CuMn /A, p NbTib = A NbTi /A with A=A Cu +A CuMn +A NbTi (b stands for billet) -  can be measured on strands but p Cu and p CuMn probably not - To compute the real values of p Cu and p CuMn in the strands, we are obliged to assume : p CuMn /p CuMn = p CuMnb /p Cub. With this assumption, we have: The linear resistance of a SIS300 cable with CuMn inter-filamentary matrix is given by:

9. Variations of the Linear resistance of a cable with CuMn E. Floch.GSI. Intas_wire_19Fe09 The cable linear resistance depends on P CuMnb /P Cub, , d s, RRR Cu and  CuMnIF (IF for inter-filamentary matrix): - To make Quench calculations, we must know in which interval rl varies - This interval must be defined in advance: that means the interval is in the cable specification:  CuMnbulk = bulk resistivity of CuMn 0.5%wt ( .m) 1.6 10 -8   1.9 10 -8 at 4 K 3.3 10 -8   3.6 10 -8 at 300 K r = cable linear resistance (in  /m)r (10K) min   r (10K) max r (300K) min   r (300K) max r ( SIS300 dipole) 0.00025  r (10K)  0.00075  /m 0.060  r (300K)  0.065  /m - The measurement on each spool piece must give rl(10K) and rl(300K) and not RRR strand

10. Minimum critical current density E. Floch.GSI. Intas_wire_19Fe09 - The knowledge of Ic and Jc strand is of importance to analyze the training behavior and compute the temperature margin (which will be used to analyze beam induced quenches) - The strand specification gives : I cNbTi (B ref ) > I cNbTi (B ref ) min. If there is no current sharing between strands, the corresponding minimum critical density is: - For SIS300 dipoles and quadrupoles : J cNbTi (5T) min  2700 A/mm 2, - For the SIS100 dipole: B ref = 2 or 5 T?, if 2 T, what value for J cNbTi (2T)? B c (4.7K,I) computed consideringJ c_NbTi (4.22K,B) of EAS wire produced in 2004 actual strands produced in 2006 J cNbTi (4.22K,5T) (A/mm 2 )30002662 J cNbTi (4.22K,2T) (A/mm 2 ))54904324 I ml_4.7K_computed = max on load line (A)100408950 I 0 /I ml_4.7K_computed (%)7180 I c (2.26T, 4.7K) (A)117379878 T cs (7166A, 2.26T)6.115.70  T ma =T cs (7166A, 2.26T)-4.7 (K) 1.411.00 Influence of J c on T cs (SIS100 straight dipole, load lines computed by C. Muehle in 2007) (these load lines not the same than those measured on the BNG prototype) The influence of Jc on T cs -T He is strong. The variations of  and d s on T cs -T He must also be considered

11. Proposal for cable specification templates E. Floch.GSI. Intas_wire_19Fe09  I c (4.2K,B ref ) min with specification d saverage = strand diameter0.5 mm dsds  2.5  m  average = Cu/NbTi 1.5  0.08 or  0.1 RRR Cu 100   280 B ref (T)2 T for SIS100 and 5 T for SIS300 I c (4.2K,B ref ) = critical current of the strand Warning: the specification is on I c not on J cNbTi J cNbTi (4.2K,2T) min = 4700 A/mm 2 or J cNbTi (4.2K,5T) min =2700 A/mm 2 For a strand having a Cu inter-filamentary matrix The values inside the templates are only indicative. Real values will be defined by magnet designers

12. Proposal for cable specification templates E. Floch.GSI. Intas_wire_19Fe09  I c (4.2K, 5T) min = 547 A with proposed specification d saverage = average strand diameter 0.825 mm dsds  2.5  m  average = (Cu+CuMn) /NbTi 1.6  0.1 I c (4.2K,5T) = critical current of the strand J cNbTi (4.2K,5T) min =2781 A/mm 2 (quite an ambitious value)  CuMnbulk = bulk resistivity of CuMn 0.5%wt 1.6 10 -8   1.9 10 -8 .m at 4 K 3.3 10 -8   3.6 10 -8 .m at 300 K r = cable linear resistance 0.00025  r (10K)  0.00075  /m 0.060  r (300K)  0.065  /m For the SIS300 dipole cable with a CuMn inter-filamentary matrix (Ic_strand(4.2K,5T)=547 A was chosen by INFN in Autumn 2007) The values inside the templates are only indicative. Real values will be defined by magnet designers

13. Aim of quench protection, example of SIS100 dipole E. Floch.GSI. Intas_wire_19Fe09 - Like LHC magnets, SIS100 and SIS300 dipoles and quadrupoles will have their coil to ground voltage (V cg ) tested at 3 kV at warm and at cold. - The EU law for AC applications states: V test = 2 * Vmax + 500, V max = V cgm should be kept below 1250 V - Aim of the protection system for SIS100 and SIS300 dipoles and quadrupoles: V cgm < 1250 V hotspot temperature T m < 350 K when protection scheme works fine T m < 350 K for a defined failure of the protection scheme - The 108 SIS100 dipoles (in series) are protected with 6 dump resistors - Because quench threshold in bus bars (V thb ) = 2 * quench threshold in magnet (V thm ), the hotspot temperature in bus bar (T mb ) > hotspot temperature in magnet (T mm ) - The dump resistance (R d ) in chosen so that T mb = 350 K when 6 six dump resistor are activated, - If one dump resistor opens of a delay of t f : t f < t fm for which T mb = 450 K V cgm = 7/36*R d *I < 1250 V

14. Strand example for SIS100 single layer dipole E. Floch.GSI. Intas_wire_19Fe09 Strand proposed by H. Mueller in Feb 2009 n° strands23 ds = strand diameter (mm)0.8  ds  0.005  =(Cu+CuMn) / NbTi 1.4  0.1 proposed byHMEF Jc_NbTi_min(4,2K, 2T) (A/mm2)46005030 Ic_min(  max =1.5,,ds_min=0.795 mm,4.2K,2T) (A)741810 Ic_min(al_max,ds_min,THe,Bmax) (A)735803 T He (K) 55 T cs -T He_  max=1.5,ds_min=0.795 mm (K)0.831.05 T cs -T He_  min=1.3,ds_max=0.805 mm (K)1.111.31 (in 2007, the single layer dipole version CSLD-8b considered  = 1.5)

15. Quench study for SIS100 single layer dipole (CSLD-8b) E. Floch.GSI. Intas_wire_19Fe09 I (A)12746 L (mH)0.553 V thb (quench threshold in bus bars) (mV)300 (Cu+CuMn)/NbTi1.3 strand diameter (mm)0.795 Inter-filamentary matrixCuCuMn CuNi8.17 A_all_strands_min (mm2)11.42 A_NbTi (mm2)4.96 A_(Cu+CuMn) (mm2)6.45 n° of filaments18144 df: filament diameter (micron)3.89 s/df0.1 s: interfilamentary spacing (micron)0.389 ro_cuMn_bulk_max_4K (ohm/m)1.60E-08 ro_cuMn_bulk_max_300K (ohm/m)3.60E-08 ro_cuMn_IFM_4K (ohm.m)1.77E-08 ro_cuMn_IFM_300K (ohm.m)3.77E-08 ACuMn (mm2)0.001.66 ACu (mm2)6.454.79 (3 experimental points measured in Dubna on Nuclotron dipole)

16. Quench study for SIS100 single layer dipole (CSLD-8b) E. Floch.GSI. Intas_wire_19Fe09 I (A)12746 Interfilamentary matrixCuCuMn xf0.47 Mitts 350K (1E6 A2.s)15.6012.35 Vpf (m/s)18.7 t rt (time to reach Vth = 300 mV) (ms)14.111.2 t rt +t v +t o =t Rd (time at I = cte) (ms)25.122.2  350K =2*( Mitts 350K / I 2 -t Rd ) (s) 0.1420.108 R d = L string /  350 K (ohm) 0.42120.555 Mitts 450K (1E6 A2.s)17.1013.69 t fm (ms)9094 V cgm (V)10441376 IFMCuCuMn xf0.30.40.470.60.30.40.470.6 Vcgm (V)1199110310449521591145713751244 - Using CuMn: the increases of V cgm is between 300 and 400 V and V cgm - With CuMn : 1244 < V cgm < 1591 V which is above our target of 1250 but could still be acceptable - The best would be to have 2 coils for the SIS100 single layer prototype (one with Cu and the other with CuMn) so that we can make a choice based on experimental data

17. Conclusions E. Floch.GSI. Intas_wire_19Fe09 - To perform appropriate quench calculations, the intervals in which the cable characteristics vary must be defined - For a Cu inter-filamentary matrix, specifying 100 < RRR Cu < 280 is sufficient - For a CuMn inter-filamentary matrix, RRR strand ≠ RRR Cu. The specification will be on the linear resistance: rl(10K) min < rl(10K) < rl(10K) max and rl(300K) min < rl(300K) < rl(300K) max - I c_strand (B ref ) min should be defined using J c (B ref ) min,  min and d smin. - B ref = 5 T for SIS300 dipoles, B ref and corresponding J c should be defined for SIS100 dipoles (2 or 5 T?) - For the strand series production: - one complete set of measurement : , d s, RRR Cu or (rl(10K) and rl(300K)), I c (4.2K,Bref) or I c (4.2K) at 0.5, 1,2,3, 5 and 6 T - one complete set of measurement every spool piece - every billet, measurement of  CuMn at 4, 77 and 300 K - Measurements after the cable production are still to be defined (Detailed explanations on strand specifications are given in the internal note "MT Internal Note: MT-INT-ErF-2008-007") - Quench calculations on single layer dipole (CSLD-8): with Cu matrix: the max coil to ground voltage 950 < V cgm < 1200 V below the upper limit of 1250 V with CuMn inter-filamentary matrix:1250 < V cgm < 1600 V above the upper limit of 1250 V - Best procedure to decide Cu or CuMn is to test 2 different coils inside the single layer dipole prototype