Quench detection for Mutiplerts: Introduction - The Super-FRS and its magnets - 2 options for multiplet magnets: low current (I < 600 A), high current (I > 1000 A) - Options for powering the magnet: - local copper current leads (low and high current) - local HTS current leads (high current) - superconducting bypass line with copper current leads (high current) - superconducting bypass line with HTS current leads (high current) - Cost of quench detection for the different options - Basic characteristics of the superconducting bypass line - Radiation hardness of HTS current leads - Conclusions E. Floch. FAIR/MT. 22 Jan09

162 magnets distributed in 30 cryostats Super-FRS magnets dipole quadrupole (long) (short) octupole hexapole Steerers total 28 22 46 40 42 12 190 224 A 162 magnets distributed in 30 cryostats E. Floch. FAIR/MT. 22 Jan09

Local Copper current leads "Local current leads" means located inside one multiplet cryostat This option is : - that considered in the FBTR - valid for I < 300 A and could also be used for I up to 3 kA - the simplest, the most reliable and cheapest for quench detection E. Floch. FAIR/MT. 22 Jan09

Local HTS current leads Quench detection for one HTS lead is more complex and cost 826 € extra per lead (268 k€ extra for 162 magnets without voltage taps cabling) E. Floch. FAIR/MT. 22 Jan09

SC bypass line with Cu leads Only for high current option One extra bridge per magnet is needed to detect a quench in the superconducting bus bars ( 122 k€ extra for 162 magnets without voltage taps cabling) E. Floch. FAIR/MT. 22 Jan09

SC bypass line with HTS leads Only for high current option One extra bridge per magnet is needed to detect a quench in the superconducting bus bars ( 122 k€ extra for 162 magnets without voltage taps cabling) Quench detection for one HTS lead is more complex and cost 826 € extra per lead (268 k€ extra for 162 magnets without voltage taps cabling) E. Floch. FAIR/MT. 22 Jan09

Extra cost for quench detection Option (28 dipoles and 162 magnets in multiplets) bridges for magnets Bridges for bus bars CLQD1 (Cu leads) CLQD2 (HTS leads) quench control sys (k€) Voltage taps cabling (k€) Total Cost (k€) extra cost (k€) Cu local current leads 190 380 20 60 289 local HTS leads 56 324 108 604 316 Bypass line + Cu leads 162 194 545 256 Bypass line + HTS leads 350 968 679 E. Floch. FAIR/MT. 22 Jan09

SC bypass line Very probably: - the bypass line will be independent of the He supply line - 3 cooling schemes (magnets, bypass line, current lead boxes) are required - 4 extra feed through per magnet - 10 extra junctions (sc/sc or sc/Cu) per magnet E. Floch. FAIR/MT. 22 Jan09

SC bypass line: branches in sc joints - For a rigid SC bypass line that has 5 branches and feeds 30 cryostats, we can imagine to build it in 50 pieces - Each bypass line piece is different (length, n° of bus bars, and maybe diameter) - At the junction between 2 pieces, we will have to make on average 162 joints - We can estimate that the bypass line requires 9720 (162*50 +10*162) sc joints more than the option with local current leads (difficulty to locate a bad sc joint) - Such a Bypass line could cost several M€ E. Floch. FAIR/MT. 22 Jan09

Radiation harness of Bi223 LHC HTS current leads use Bi2223 tape with Ag matrix Irradiation of Bi2223 tape with Ag matrix Ref Protectile Energy (MeV) Fluence (projectile/cm2) Irradiation at Ic_irradiated / Ic_vergin 1 neutrons 17 (average) 1015 77 K 2*1015 300 K 1.02 2 protons 50 5*1017 0.3 Ref 1 : Ballarino, A. et al., “Effect of fast neutron irradiation on current transport properties of HTS materials”, http://at-mel-cf.web.cern.ch/at-mel-cf/resources/Irradiation_tests_Eucas.pdf. Ref 2 : A. F. Zeller, R. M. Ronningen, A. Godeke, L. H. Heilbronn, P. McMahan-Norris, and R. Gupta. "RADIATION DAMAGE TO BSCCO-2223 FROM 50 MEV PROTONS ", ICMC 2008 proceeding, p416-422. see http://proceedings.aip.org/proceedings/cpcr.jsp Before deciding to use HTS local current leads, one must be sure that the HTS tapes can withstand the expected radiation level in the Super-FRS E. Floch. FAIR/MT. 22 Jan09

Conclusions - For the high current option, we could think of a superconducting bypass line. - Such a SC bypass line has the following drawbacks: complex design (at least 50 individual pieces), 2 extra cooling schemes, 648 feed through, about 10 000 SC joints, quench detection cost would increase from 290 to 970 k€ - Because of all these disadvantages, the SC bypass line should be avoided - The simplest, most reliable and cheapest solution is to use local copper current leads - which is perfectly appropriate for I < 300 A - could be imagined even for higher current - In case HTS current leads are chosen (to lower cryogenic losses), one must be sure that the radiaton level in the Super-FRS is not dammaging the Bi2223 tape. E. Floch. FAIR/MT. 22 Jan09