preliminary design for the coupling coil cryostat in mice
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MICE CM16 2006.10, CCLRC/UK
Li Wang
Preliminary Design for the Coupling Coil Cryostat
in MICE
Institute of Cryogenics and Superconductivity Technology
Harbin Institute of Technology
P.R.China
MICE CM16 2006.10, CCLRC/UK
Li Wang
According to the “Technical Specification on MICE Coupling Solenoid
Magnet Fabrication, Assembly, Test and Shipping”, ICST/HIT carried out t
he preliminary engineering design on the coupling magnet cryomodule si
nce this August. The following persons have been involved in the current
design in ICST.
Dr. Lin X.Jia, Professor
Dr. Li Wang, Professor
Mr. C.S.Liu, Engineer
Mr. G. Hang, Engineer
H.Wu, Ph.D. candidate, numerical calculation
L.K.Li, M.S. candidate, numerical calculation
The detailed calculations and numerical simulations are going on.
MICE CM16 2006.10, CCLRC/UK
Li Wang
The presented include:
Process flow diagram
Cryostat
Helium vessel
Self-centered supports
Current leads
MICE CM16 2006.10, CCLRC/UK
Li Wang
Flow Diagram
LHe dewar
GHe storage tank
Coupling magnet cryomodule
Vacuum pumping
Cryo-cooler
He compressor
MICE CM16 2006.10, CCLRC/UK
Li Wang
The precooling or test system is composed of
• LHe dewar (250L, 500L available in ICST )
• LN2 dewar (if necessary, 200L, 500L available in ICST )
• GHe storage tank (5m3, 10m3 available in ICST )
• He compressor
• Transfer lines
• Safety device (relief valves, rupture disc etc.)
• Valves
• Vacuum pumping system (available in ICST )
• Cooling water system (available in ICST )
MICE CM16 2006.10, CCLRC/UK
Li Wang
Schematic of coupling magnet precooling system
MICE CM16 2006.10, CCLRC/UK
Li Wang
Cryostat
The cryostat is composed of
• Vacuum chamber made of stainless steel
• Radiation shield made of annealed OFHC copper
• Helium vessel made of stainless steel or 6061-T6 Aluminum
• Coil assembly consisting of NbTi/Cu SC conductors, bobbin, ground insulation, epoxy and support cylinder (or banding)
• Copper leads + HTS leads
• Supports
• LHe condenser
• Cryo-cooler
• Piping
• Bayonets and fittings
• Feedthroughs for temperature sensors, heater, level meter, voltage taps etc.
• Instrumentation including temperature sensors, heater, level meter, pressure transducers etc.
• MLI insulations and electrical insulations
MICE CM16 2006.10, CCLRC/UK
Li Wang
Cryo-cooler
Helium vessel
Vacuum vessel
LHe piping
Cold-down supply piping
Shields
Supports
VHe pipingCold-down return piping
Vacuum port
Feedthrough
MICE CM16 2006.10, CCLRC/UK
Li Wang
Copper lead
1st stage cold head
HTS lead
2nd stage cold head
Eddy current interrupt slot
Supports
Flexible Cu strap
Bayonet
Piping to relief device
Condenser
MICE CM16 2006.10, CCLRC/UK
Li Wang
Up to the magnetic field distribution, the location of HTS leads and cryocooler will be changed.
MICE CM16 2006.10, CCLRC/UK
Li Wang
Radiation shield is divided into four parts for assembly.
MICE CM16 2006.10, CCLRC/UK
Li Wang
He vessel Bobbin
Coil
Support cylinder
MICE CM16 2006.10, CCLRC/UK
Li Wang
Magnet cryostat components
MICE CM16 2006.10, CCLRC/UK
Li Wang
Helium Vessel
Option A
Directly made of coil bobbin, end plates and cover cylinder
Coil is cooled through conduction
Simple structure, but thick Al material needed
A separated vessel to contain the coil assembly
Coil is cooled either through conduction or directly by LHe
Complex structure and assembly
Option B
MICE CM16 2006.10, CCLRC/UK
Li Wang
Two cooling schemes for Option B:
Temperature distribution
SS vessel wall
Liquid helium
SS Support cylinder
Coil
Ground insulation
Al Bobbin
4.2K
q-radiation=0.2W/m2
Helium vessel is made of stainless steel.
The coil is cooled through conduction by liquid helium.
SS thickness=15mm
△Tcoil<0.1K
MICE CM16 2006.10, CCLRC/UK
Li Wang
The coil is cooled directly by liquid helium.
4.2K
q-radiation=0.2W/m2 Tcoil<0.066K△
MICE CM16 2006.10, CCLRC/UK
Li Wang
Helium passage
Helium passage
Bobbin
Coil
Support cylinder
MICE CM16 2006.10, CCLRC/UK
Li Wang
The coil is cooled through conduction by liquid helium.
q-radiation=0.2W/m2 Tcoil<0.1K△
SS vessel wall
Liquid helium
Al Support cylinder
Coil
Ground insulation
Al Bobbin
4.2K
MICE CM16 2006.10, CCLRC/UK
Li Wang
4.2K
The coil is cooled directly by liquid helium.
q-radiation=0.2W/m2 Tcoil<0.066K△
MICE CM16 2006.10, CCLRC/UK
Li Wang
15mm SS in thickness
Supports
Stress analysis for Option B: to consider the radial, longitudinal and gravity forces as well as the 4 bara pressure inside.
MICE CM16 2006.10, CCLRC/UK
Li Wang
MICE CM16 2006.10, CCLRC/UK
Li Wang
To only consider the 4 bara pressure inside for SS helium vessel.
MICE CM16 2006.10, CCLRC/UK
Li Wang
Option A: directly made of coil bobbin, end plates and cover cylinder
6061-T6 Al
6061-T6 Al
4.2K
The coil is cooled through conduction by liquid helium.
q-radiation=0.2W/m2 Tcoil=0.04K△ Al thickness=25mm
MICE CM16 2006.10, CCLRC/UK
Li Wang
25mm Al in thickness
Supports
Stress analysis for Option A: to consider the radial, longitudinal and gravity forces as well as the 4 bara pressure inside.
MICE CM16 2006.10, CCLRC/UK
Li Wang
MICE CM16 2006.10, CCLRC/UK
Li Wang
To only consider the 4 bara pressure inside for Al helium vessel.
MICE CM16 2006.10, CCLRC/UK
Li Wang
Self-centered Supports
MICE CM16 2006.10, CCLRC/UK
Li Wang
Supports without 50K intercept
16mmx12.5mm, 175mmx2
G-10 band SS
~50K
MICE CM16 2006.10, CCLRC/UK
Li Wang
Supports with 50K intercept
~50K
MICE CM16 2006.10, CCLRC/UK
Li Wang
Total
50K Cold Mass Support Heat Load (W) 0.13162 1.05296
4.2K Cold Mass Support Heat Load (W) 0.008686 0.069488
Total
Total Heat Leak from the Cold Mass Support (W)
0.074348 0.594784
Heat loads from cold mass supports
Supports with 50K intercept
Supports without 50K intercept
The structure and dimensions of the supports need to be further optimized.
MICE CM16 2006.10, CCLRC/UK
Li Wang
Current leads
The current lead for coupling coil consists of a conduction-cooled copper lead that carries current from room temperature to intercept temperature (the first stage of cryocooler) and a HTS lead that carries current from the intercept to the coil.
Copper lead
HTS lead
MICE CM16 2006.10, CCLRC/UK
Li Wang
Design for Copper current leads
dz
TL
z
Q+dQ
Q
I
TH
2( )*0
dQ T I
dz A
* ( )*dT
Q A k Tdz
2 2 22 ( ) ( )H
L
T
L H TQ Q I k T T dT
;
;
,
,L L
H H
T T Q Q
T T Q Q
2 ( ) ( )H
L
Topt
T
Qk T T dT
I
Energy equation:
(1)
(2)
(3)
0HQ Assuming:
(4a)
( )
( )
H
L
T
T
L k TdT
A Q T (5)
( )
2 ( ) ( )
H
HL
T
TTopt
T
LI k T dT
A k T T dT
(6a)
0 ( )H
L
T
I T
AQ k T dT
L
The optimized heat flow into the cold end of the lead:
MICE CM16 2006.10, CCLRC/UK
Li Wang
2 20 ( )opt
H L
QL T T
I
2 20
1 ( )H
L
T
Topt H
LI k T dT
A L T T
0( ) ( )k T T L T To apply Wiedemann-Franz law for most metal and alloy,
(4b)
(6b)
40 45 50 55 60 65 7011.2
11.3
11.4
11.5
11.6
11.7
11.8Qopt(W) ~TL(K) at I=250A
Cold temperature [K]
Opt
imiz
ed h
eat f
low
[W]
11.8
11.2
Q opt T L
7040 T L
200 210 220 230 240 250 260 270 280 290 30010
11
12
13
14
15
16
17
18
19
20L/A(mm-1)~I(A)at 50K, 60K
Current [A]
L/A
[m
m-1
]
20
10
F opt50K I( )
F opt60K I( )
300200 I
MICE CM16 2006.10, CCLRC/UK
Li Wang
200 210 220 230 240 250 260 270 280 290 3008
9.5
11
12.5
14Qopt(W) ~I(A) at 50K, 60K
Current [A]
Opt
imize
d he
at flo
w[W
]
14
8
Q opt50K I( )
Q opt60K I( )
300200 I
For I=250A
TL=50K, Qopt=11.563W
TL=60K, Qopt=11.49W
For I=220A
TL=50K, Qopt=10.176W
TL=60K, Qopt=10.112W
MICE CM16 2006.10, CCLRC/UK
Li Wang
Material RRR Nominalcurrent
Maximumcurrent
Size
D L
pure copper 10 220A 250A 8mm 0.4m
Parameters used for numerical simulation of the copper lead by FLUENT
I=250A, D=8mm, L=0.4m, Q=14.27W
MICE CM16 2006.10, CCLRC/UK
Li Wang
Temperature distribution along the copper lead at I=300A, D=8mm, L=0.4m
Q=15.245W
MICE CM16 2006.10, CCLRC/UK
Li Wang
Temperature distribution along the copper lead at I=500A, D=8mm, L=0.4m
T-warm-end>300K
MICE CM16 2006.10, CCLRC/UK
Li Wang
Temperature distribution along the copper lead at I=300A, D=8mm, L=0.7m
T-warm-end>300K
MICE CM16 2006.10, CCLRC/UK
Li Wang
TypeOuter
Diameter (mm)Length (mm)
Cross-sectionarea ( mm2)
CriticalCurrent (A/77K)
Silver contactlength (mm)
CSL-18/80.3 18.0 80 78 750 15
CSL-18/120.3 18.0 120 78 750 15
CSL-18/160.3 18.0 160 78 750 15
Parameters of HTS Current Leads
*Data from Sumitomo Electric
Superconducting tubes of BiPbSrCaCuO (Bi-22
23 phase) ceramics with silver covered ends of
a low contact resistance are suitable for current
leads effectively reducing heat leak into superc
onducting magnets. For better mechanical prot
ection the leads may be encased in metal or G-
10 tubing.
The nominal current for the HTS lead is 220A, and it must be capable of carrying 500A when the high-temperature end of the lead is nominally at 60K and at 1.5T.
MICE CM16 2006.10, CCLRC/UK
Li Wang
60 80 100 120 140 160 180 2000
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08Heat load along the HTS lead
Length of HTS [mm]
Hea
t loa
d [W
]0.08
0
Q HTS x( )
20060 x
H
L
T
TdTTk
L
AQ )(
MICE CM16 2006.10, CCLRC/UK
Li Wang
Heat loads from the current leads
HTS leads (50K-4.2K)
L (mm) Do (mm) Thickness (mm) Q (W)
80 18.0 1.505 0.0573*2
120 18.0 1.505 0.0382*2
160 18.0 1.505 0.0286*2
Copper leads (300K-50K)
I (A) L (mm) D (mm) Qopt (W)Qopt (W)
w/o current
(L/A)opt
(1/mm-1)Qreal (W)
Qreal (W)
w/o current
(L/A)real
(1/mm-1)
300 400 8.00 13.876*2 8.587*2 11.781 15.245*2 12.712*2 7.958
27.752 17.174 30.49 25.424
250 400 8.00 11.563*2 7.156*2 14.137 14.27*2 10.527*2 9.610
23.126 14.312 28.54 21.054
Since the performance of HTS leads will be greatly influenced by the magnetic field, we should consider it while to select the commercial leads.
MICE CM16 2006.10, CCLRC/UK
Li Wang
Winding Process
Winding procedure and materials to be used need further detailed discussion.
MICE CM16 2006.10, CCLRC/UK
Li Wang
The detailed further calculations and analyses are g
oing on provided no change on the coil design such as t
he coil itself and its quench protection, vacuum vessel,
supports, helium condenser, piping, safety device, instr
uments, interface to RF cavity module and so on.
MICE CM16 2006.10, CCLRC/UK
Li Wang
ICST contribution summary up to date
Two professors (one half time and one quarter time)
Two engineers (one and a half time)
Two graduates (full time)
ICST future possible contributions (year’07)
Research fund $10k
Three professors (two half time and one quarter time)
Four engineers (full time)
Three graduates (full time)
Four mechanical/cryogenic technicians (full time)
MICE CM16 2006.10, CCLRC/UK
Li Wang
THANK YOU
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