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Investigations concerned with development
of SC dipole for the SIS 300 accelerator
I. Bogdanov, S. Kozub, V. Pokrovsky, L. Shirshov,
P. Shcherbakov, V. Sytnik, L. Tkachenko, V. Zubko, Institute for
High Energy Physics (IHEP), Protvino, Moscow region, Russia,
G. Moritz, J. Kaugerts, Gesellschaft fГјr Schwerionenforschung
(GSI), Darmstadt, Germany
Main parameters of the SC-dipole for the SIS-300
Magnetic field
6T
Field ramp rate
1 T/s
GSI trapezoid field cycle
Full coil aperture
diameter
Effective magnetic
length
1,6 – 6 - 1,6 T
100 mm
2900 mm
The main problems
пЃ¬ During the UNK project,
superconducting dipoles have
been developed and produced
in a pilot industrial batch of 25
magnets. The operating field of
the dipoles was 5.11 T, at
0.11 T/s ramp rate.
пЃ¬ Improvements of the present
UNK dipole design will be
considered to extend the
operating range of the dipoles
to 6 T, with ramp rates of 1 T/s.
пЃ¬ To design and choice of new
current carrying element
both wire and cable.
пЃ¬ To select of new material for
iron yoke.
пЃ¬ To choice
of magnet
geometry (2D and 3D) of
computer simulation
пЃ¬ To minimaze of total AClosses and their components
in the coil and iron yoke.
Steel choice.
Two candidate steels 2212 and M250-50A were chosen for analysis of the
influence of these steels on field quality, as well as on heat loss in the iron
yoke during magnet pulsed operation.
Steel 2212 is better, from the viewpoint of field quality, but full hysteresis
losses in iron (for 1-m dipole) of this steel is 44.8 [J/m] and 24.8 [J/m] for
M250-50A.
Si, % Ms, T (4.2 K) Ms, T (300 K)
3.3
2.09
2.04
2.4
2.11
2.06
1.3
2.18
2.13
2.4
2.2
M agnetic in duction , B , (T )
Steels
M250-50A
3413
2212
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
2212
(1 .3 % S i)
M 2 5 0 -5 0 A (3 .3 % S i)
0.2
0.0
10 0
1 00 0
1 00 0 0
M a g n etic stren g th , H , (A /m )
1 0 00 0 0
Characteristics of SC-cable
пЃ¬ Cable consists of 36 strands
with 100-mm (16.8Вє)
transposition pitch and has
core made with 25-Ојm thick
stainless steel. Strands in the
cable are covered by 0.5-Ојm
thick stabrite coating.
пЃ¬ The cable has three layers allpolyimide film insulation,
having 0.125-Ојm and 0.098Ојm radial and azimuthal
thickness after the coil
assembly
пЃ¬ Strand (0.825-mm
diameter) consists 3.5Ојm filaments of Nb47%Ti
alloy, enclosed in a Cu
matrix;
пЃ¬ 5-mm filament twist
pitch;
пЃ¬ Cu/superconductor ratio
is 1.4;
пЃ¬ critical current density is
Jc = 2700 A/mm2 (at 5 T,
4.2 K).
Adjacent resistance Ra in 36-strand cored
cable
Preliminary heat
treatment
200п‚°C, 2 hours
Curing regimes
Ra, пЃ­пЃ—
220п‚°C, 10 min
46
200п‚°C, 2 hours
120п‚°C, 2 hours
109
200п‚°C, 2 hours
120п‚°C, 2 hours
83
200п‚°C, 4 hours
220п‚°C, 10 min
16.7
200п‚°C, 4 hours
120п‚°C, 2 hours
118
Measurements of Rc
пЃ¬ Measurements
of
Rc
were
performed on the small pieces of
SC cable. Side ridge of cable were
cut. Current flowed across cable
through the area of 13п‚ґ12 mm2
(~120 crossover joints).
пЃ¬ Pressure applied to this area at
4.2 K was varied from 0 to
90 MPa. Above 20 MPa the
pressure dependence of Rc have
gentle dip.
пЃ¬ For the cables exposed by 4 hour
heat treatment The crossover
resistance Rc at 50 Mpa and 4.2 K
(operating condition) was equal
450 and 120 mпЃ— for polyimide or
epoxy adhesive gluing regimes
correspondingly.
Tests of Straight and Bent
Superconducting Dipoles
пЃ¬ According to the technical пЃ¬ A model superconducting
requirements the SIS300
dipole, manufactured for
dipole length is close to
the UNK project, was
2900 mm and the
chosen for study of the
particle orbit radius is
influence of bending
about 50 m.
effects on magnet
characteristics. The
пЃ¬ These numbers
straight collared coil of
determine a value of the
this model magnet was
orbit sagitta inside the
tested, then bent with a
magnet of 22.5 mm.
50 m curvature radius,
and then retested.
Magnet training before and after bending
7.5
7.4
5.5
5.4
7.2
7.1
5.3
7.0
5.2
6.9
5.1
6.8
6.7
5.0
6.6
S traig h t 4.9
6.5
B en t
4.8
6.4
0
2
4
6
8
10
12
14
Q uench sequence
16
18
20
C e n tra l fie ld , B 0 , T
Q u e n c h c u rre n t, k A
7.3
пЃ¬ After bending, the dipole
began to retrain. The
maximum critical current
reached during training of
the dipole did not decrease
after its bending.
пЃ¬ Bending of the collared
dipole coil (50 m curvature
radius) did not produce turnto-turn shorts and did not
decrease ground insulation
resistance.
The results of SC-dipole test before and after
magnet bending
7 .4 4
7 .4 2
7 .4 0
7 .3 8
7 .3 6
7 .3 4
7 .3 2
7 .3 0
7 .2 8
B ent I
7 .2 6
B e n t II
7 .2 4
S tra ig h t I
S tra ig h t II
7 .2 2
0
5 .5 5
5 .5 4
5 .5 3
5 .5 2
5 .5 1
5 .5 0
5 .4 9
5 .4 8
5 .4 7
5 .4 6
5 .4 5
5 .4 4
5 .4 3
5 .4 2
5 .4 1
5 .4 0
5 .3 9
5 .3 8
100 200 300 400 500 600 700 800 900 1000
C u rre n t ra m p ra te , d I/d t , A /s
C e n tra l fie ld , B 0 , T
пЃ¬ Test results showed similar
characteristics, both in
training and in ramp rate
dependence, as well as in
field quality of the straight
and bent coils.
7 .4 6
Q u e n c h c u rre n t, k A
пЃ¬ Ramp rate dependences of the
straight and bent dipoles
before (I) and after (II) 1000
cycles of 0 – 5 T – 0 with 1000A/s current ramp rate.
Model SC-dipole Magnet for the SIS 300
General view of cross section
пЃ¬ Main parameters of the model
SC-dipole are: 100-mm coil
aperture; 86-mm mechanical
aperture and 80-mm useful
aperture (good field region).
пЃ¬ Length of the magnet is 1 m.
The magnet has 6-T central
magnetic field with 1 T/s
operating field ramp rate.
пЃ¬ Operating current of 6.615 kA
gives 6-T central field with real
magnetic permeability in the
iron yoke.
AC losses in the 1-m model SC-dipole
Hysteresis in the SC-coil
42.7 [J/m]
Matrix losses in the SC-wire
13.9 [J/m]
Cable losses
11.4 [J/m]
Hysteresis losses in the iron
(using measured specific losses
in steel M250-50)
24.8 [J/m]
Total AC-losses in the SC-coil
and iron yoke
92.8 [J/m]
CONCLUSION
пЃ¬ Magnetic properties of tree types of cold rolled thin sheet of electrical
Si steels have been measured at room and 4.2 K temperatures. For the
iron yoke of the SIS-300 dipole was choice steel type M250-50A.
пЃ¬ The contact resistances (Ra and Rc ) of SC-cable were measured that
permitted to calculate AC-losses of SIS300 dipole.
пЃ¬ Bending of the collared dipole coil (50 m curvature radius) did not
produce turn-to-turn shorts. Training and ramp rate dependence of
the straight and bent dipoles are similar. AC-losses were practically
unchanged, after dipole bending.
пЃ¬ The magnetic, thermal and mechanical calculations of the SIS300
dipole was carried out.
пЃ¬ The next step consists of manufacture and test 1-meter SC dipole
model with the parameters of the last developed design.
Спасибо за внимание!
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