cryogenics for arc and transfer line magnets
DESCRIPTION
LHC Accelerator Research Program bnl-fnal-lbnl-slac. Cryogenics for arc and transfer line magnets. Outline: LER cryogenic system design LHC cryogenics infrastructure at CERN LER arc magnet cryogenics Current leads for arc magnets LER transfer line magnet cryogenics - PowerPoint PPT PresentationTRANSCRIPT
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
1
LHC Accelerator Research Programbnl-fnal-lbnl-slac
Outline:–LER cryogenic system design–LHC cryogenics infrastructure at CERN–LER arc magnet cryogenics–Current leads for arc magnets–LER transfer line magnet cryogenics–Current leads for fast switching magnets–Summary
Cryogenics for arc and transfer line magnets
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
2
LER cryogenic system design
• For any cryogenic system design, first thing we need to know is to identify the heat load Q, conduction, radiation, Joule heating, etc.
• Figure out at what temperature level T this heat load is introduced into the cryogenic system, 1.9 K, 4.5 K or 50 -75 K etc.
• Then we need to know where these cryogenic cooling powers coming from and how much the temperature difference between the conductor and coolant at heat load Q and temperature T
Q, Tsm, THe
Magnet
Thermal shield Cryostat
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
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LHC cryogenic system layout
• 5 cryogenic islands• 8 refrigerators
• 2 at P4, 6 and 8• 1 at P1.8 and P2
• 1 refrigerator serves 1 sector, 3,300 m
• Each refrigerator is 18 kW @ 4.5K and 600 kW pre-cooler
• LER will use LHC existing cryogenic infrastructure as show below
P4 P6
P3 P7
P2 P8
P1
P1.8
P5
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
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LHC helium refrigerator system setup
300 K 90 K 75 K 50 K 20 K 4.5 K
LHC supply
LHC return
Shield supply
Shield return
HP
MP
LP
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
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LHC cryogenic distribution line (QRL)
Header B
4 K, 16 mbar
1.9 K pumping line
Header C
4.6 K, 3 bar
Cold mass, 1.9 K, intercept and beam screen
Header D
20 K, 1.3 bar
Beam screen cooling return line
Header E
50 K, 20 bar
Shield cooling supply within arc cryostats
Header F
75 K, 19 bar
Shield cooling return
Cryogenic Distribution Line (QRL)
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
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Installed refrigeration capacity in the LHC sectors
Temperature level
High-load sector *
Low-load sector -
50 – 75 K [W]4.6 – 20 K [W]4.5 K [W]1.9 K LHe [W]4 K VLP [W]20 – 280 K [W]
330007700300240043041
310007600150210038027
* The high-load sectors are 1-2, 4-5, 5-6 and 8-1.
- The low-load sectors are 2-3, 3-4, 6-7 and 7-8.
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
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Static heat in-leaks in standard cell arc, DS and LSS
Temperature level
50 – 75 K [W]
4.6 – 20 K [W]
Cell 482 14.0Are (23 cell)
11090 323
DS 1,2,4,5,6 & 8 *
788 28
DS 3 & 7 * 794 28LSS 1 & 5 *
658 15
LSS 2 & 8 *
791 14
LSS 3 & 7 *
130 3
LSS 4 * 508 5LSS 6 * 232 0Total 15,473 430
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
8
Static heat in-leaks in distribution system
Temperature level
50 – 75 K [W]
4.6 – 20 K [W]
Sector 1-2, QRL + Other
10325 + 500
245 + 190
Sector 2-3, QRL + Other
9894 + 95 235 + 67
Sector 3-4, QRL + Other
9853 + 156 237 + 93
Sector 4-5, QRL + Other
10353 + 746
247 + 198
Sector 5-6, QRL + Other
10300 + 586
245 + 183
Sector 6-7, QRL + Other
9723 + 156 231 + 93
Sector 7-8, QRL + Other
9740 + 156 232 + 93
Sector 8-1, QRL + Other
10723 + 586
248 + 183
Other means Interconnection boxes, local transfer lines and vertical transfer lines
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
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LER arc main dipole and LHC quads
- LER will use VLHC drive conductor design
- LER ring length 26658.9 m- LER arc magnet sector length ~ 3.3
km- Heat load at 4.5 K for each sector is
346 W- Cryogenic support for each LER arc
magnet ring: 18 g/s @ 3 bar, 4.6 K supply, outlet temperature <6.0 K
- He inventory for whole LER ring is 1700 kg
- LER magnets and current return line will share the same current leads which can carry a peak current of 72 kA
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
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VLHC transmission line magnet cryogenics
Drive conducto
r
Current return
Shield
T in (K) 4.5 4.52 37P in (bar)
4 3.8 17
T out (K) 5.57 5.8 70P out (bar)
2.8 1.9 13
Heat loads (W/m)
0.044 0.024 1.534
Distance (m)
19400 19400 38800
Mass flow (g/s)
60 120 60
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
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LER drive and return conductors
• Same design for LER drive conductor and return conductor•LER arc magnet length : 12m•Beam pipe gap: 30 mm•Peak current : 72 kA•Helium supply is 3 bar, 4.6K•Helium return is 2.5 bar, 6.0K•Helium flow : < 20 g/s for each sector conductors•Pressure drop for each sector is < 0.5 bar
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
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LER arc magnet correctors
Every half-cell will have a set of corrector magnets. To place them, the drive conductor is moved up 230 mm, next to the return conductor thus creatinga field-free zone below.
Arc magnet correctors and their count (based on the VLHC design):
Dipole (Horiz. or Vert.) 0.8T 0.5 m 410 Quadrupole 20 T/m 0.5 m 410 Sextupole 1400 T/m2 0.8 m 410
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
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Main parameters of three types of conductors
Drive
bus
Return bus
Bus in correction
spaceCu/Sc ratio in
strand1.8 1.8 1.3
Diameter (mm)
0.648
0.648 0.808
Conductor type
Braid
Braid 9 Rutherford
CablesNumber of
strands288 288 270
Cu wire diameter
(mm)
0.64 0.64 0.64
Number of wires
240 240 288
Inner pipe diameter
(mm)
25.4 25.4 36.8
Outer pipe diameter
(mm)
38.1 38.1 50.1
Max. working pressure
(bar)
40 40 40
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
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LER driver conductor model
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
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VLHC transmission line magnet calculated heat loads
4.5 K level 40 K levelMechanical supports (mW/m)
53 670
Superinsulation (mW/m)
15 864
Beam loss (mW/m)
2 1
Splice (mW/m) 7 -Total heat loads (mW/m)
77 1535
Mechanical support is provided by the pegs spaced at 0.5 m.40 layers of MLI wrapped on the 50 K thermal shield and 20 layers on the conductor outer pipe to reduce the heat load at lower temperature level.
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
16
LER arc magnet heat loads scaled from VLHC study
4.6 – 6.0 K level
50 - 75 K level
Mechanical supports (mW/m)
53 670
Super-insulation, MLI
(mW/m)
15 864
Beam loss (mW/m)
2 1
Splice (mW/m) 35 -Total heat loads
(mW/m)105 1535
Heat load per arc, 3300 m
(W)
346 5066
Since LER arc magnet will use the same design as VLHC model, the heat load should be the same level as VLHC design values.
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
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LER arc magnet current ramping scheme
0
10
20
30
40
50
60
70
80
0 200 400 600 800 1000 1200 1400 1600
Tim e (sec)
I (kA
)
The current ramping scheme for LER arc magnet is shown above.Since LER arc magnet is made of superconductor, the heat loadsduring current ramping will be the splice heating and heat load dueto current leads.
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
18
Current lead for LER arc magnet ring
• We have designed and made a pair of helium vapor cooled current leads (made of copper) for VLHC study, which optimized for a DC current up to 100 kA.
• During the demonstration test of superferric magnet program, the current was ramped up to 104 kA when magnet quenched.
• The helium consumption rate is within the design target – 5.6 g/s per lead and all quenches were in the superconductors located far away from the splice between the lead and superconductor.
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
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Cryogenic system setup for VLHC study
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
20
Fast switching magnet design and cooling
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
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Transfer line magnet list
Magnet size
[mm x mm]
LER beam
vertical lift
[mm]
Magnet
length
[m]
Field
[T]
Inductance
[μH]
Peak
Voltage
[kV]
Number of magnets
Number of supplies
40 x 40 0 – 5.5 1.6 1.46 1.3 40 4 4
40 x 50 5.5 – 16.2 1.4 1.46 1.5 43 3 3
40 x 60 16.2 – 27.6 1.3 1.46 1.6 46 2 2
40 x 70 27.6 – 36.6 0.9 1.46 1.3 40 2 2
40 x 80 36.6 – 46.2 0.8 1.46 1.3 40 2 2
30 x 30 75.0 – 170.0 2.0 1.95 - - 6 1
30 x 30 170.0 – 1350.0
1.5 8.00 - - 10 1
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
22
LER fast switching magnet (V1 - V5) cryogenics
0
10
20
30
40
50
60
0 200 400 600 800
t (sec)
I (kA
)
0
50
100
150
200
0 200 400 600 800
t (sec)
Hea
t lo
ad (
W)
• Fasting switching magnet ramp scheme and Joule heating curve are shown on the left for RRR=1000 Cu.
• The magnet is cooled by 4.6 – 15 K, 3 bar helium.
• The average heat load during current ramping is 30 W per meter long conductor.
• Heat transfer between conductor surface and helium is calculated and temperature difference between the two is less than 0.1 K.
• Required helium flow is 1.5 g/s per meter long conductor to carry the heat load away.
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
23
LER fast switching magnets (V1- V5) heat loads
Cu RRR 1000Cross sectional
area (cm^2)4.36
Calculated heat load (W/m)
30.44
Total length of conductor (m)
66.4
Total heat load for FSM set (W)
2020
Helium inlet temperature (K)
4.6
Helium outlet temperature (K)
15
Enthalpy difference (J/g)
20.33
Required helium flow per meter
(g/s)
1.5
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
24
LER transfer line magnet V6 heat load
0
10
20
30
40
50
60
0 200 400 600 800 1000 1200 1400
Time (sec)
Cu
rren
t (k
A)
0
20
40
60
80
100
120
140
0 200 400 600 800 1000 1200 1400
Time (sec)
Q (
W)
LER transfer line magnet current ramping curve, ramping rate is210 A/s, first flattop is 15 kA andSecond flattop is 55 kA and then there is a long ramping down tails.
Using RRR=1000 copper and cool the magnet with 4.6 K helium, the Jouleheating within the magnet conductorwill be ~ 42 W/m. Total length of conductor is 48 m, so total heat load is 2040 W.
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
25
LER transfer line magnets (V6) heat loads
Cu RRR 1000
Cross sectional area (cm^2) 4.36
Calculated heat load (W/m) 42.5
Total length of conductor (m)
24
Total heat load for FSM set (W)
2040
Helium inlet temperature (K)
4.6
Helium outlet temperature (K)
15
Enthalpy difference (J/g) 20.33
Required helium flow per m (g/s)
2
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
26
Current leads for fast switching magnets
Another heat load for fast switching magnet is caused by heat conductionfrom current leads. Since each fast switching magnet needs a powersupply to energize, the number of PS equals number of magnet.
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
27
Current lead heat loads scaled from LHC HTS leads
LHC 13 kA HTS current lead heat leak (W) *
< 1.5 W
LER FSM 55 kA HTS current lead heat leak (W)
6.0 W
Total number of leads per arc 52
Total heat leak at 4.6 K level 312 W* HTS at CERN & LHC Current Leads by Dr. Amalia Ballarino released at website.
LER Workshop, CERN, October 11-12, 2006
Cryogenics for arc and transfer line magnets - Yuenian Huang
28
Summary
• LER arc magnet will add additional heat load of 346 W for each sector at 4.6 K to 6.0 K level and 5,000 W at 50 – 75 K level.
• LER current lead can use the same design as for VLHC design study prototype current lead, which can be used for LER arc magnet ring.
• Each fast switching magnet set will add additional 2 kW heat loads at 4.6 K level to the LHC cryogenic system.
• Each transfer line magnet set (V6) will add additional 2 kW heat loads at 4.6 K level to the LHC cryogenic system.
• Current leads for fast switch magnet will add 312 W at 4.6 K level.
• The total cryogenic capacity of current LHC infrastructure is 7700 W at 4.6 K level and 33,000 W at 50 – 75 K level.
• Helium inventory for LER ring is only 0.5 L/m, or 1700 kg (or 13 m3).
• Helium inventory for fast switching magnets is 0.24 L/m.