1. 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

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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”,
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 proceeding, p see
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

11. 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 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