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SC dipole magnet for CBM
E.A.Matyushevskiy, P.G. Akishin, A.V. Alfeev, V.S. Alfeev, V.V. Ivanov,
E.I. Litvinenko, A.I. Malakhov
JINR, Dubna
CBM Collaboration Meeting February 2008
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 2
Outline
• Original specifications• Conceptual design• Cryostat and the excitation windings• Field map calculations• Geant geometry• Further steps
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 3
The original specifications for the magnet
The magnet should provide:
An integral value of the magnetic field along Z-axis
about 1.5-2 T x m.
The maximal value of the magnetic field in a magnet
gap should amount to 2 T.
The working gap acceptance should be within 50º in
height (1.4 m) and 60º in width (1.6 m).
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 4
The conceptual project of the magnet
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 5
3D view of the magnet yoke
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 6
The details of the magnet design
Yoke shape: window frame (consists of top and bottom beams and
lateral racks). The set of three pairs of the top and bottom beams
forms the magnet’s poles. Yoke material: the magnetic steel with low carbon content (Steel
1010). Cryostats for excitation windings position: fixed on the magnet’s
yoke. Cryostat vacuum casing material: stainless steel (12Ch18N10T) Windings shape - ‘Duck nose’ form Winding material - superconducting cable with the cross-section of
7 x 4.5 mm². The cable consists of superconducting wires with
niobium-titanic strings put in a copper matrix. The ratio of the cross-
section of the superconductor area to the copper’s matrix is 1/3; the
ratio of the superconducting wires to the aluminium matrix is 1/12. Magnetic screen covers the winding in the magnet’s outlet to
reduce a field outside of the magnet.
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 7
The conceptual project of the magnet(x-y projection)
Lateral racks: Fill in device
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 8
The conceptual project of the magnet (z-y projection)
3 top beams:
3 bottom beams
Magnetic screen
Connector (vacuum-cryostats adapters)Support
basic
Top winding
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 9
The excitation windings (top winding)
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 10
The conceptual project of the magnet (winding cross-section)
Tubes with circulating liquid helium
Support legs (made fromKevlar)
Copper tubes
Vacuum casing
Heliumvessel
NitricscreenSuperisolation
4.5˚K 70-80˚K 300˚K
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 11
(X-Y) gap of the magnet along the beam
from left to right yoke edges
left screen edge
right screen edge
1.0
7 m
1.4
m
1.6
m
1.6 m
1.1 m 0.77 m0.77 m
last STS station (needs >=1.12m)
from left to right yoke edges
left screen edge
right screen edge
1.0
7 m
1.4
m
1.6
m
1.6 m
1.1 m 0.77 m0.77 m
last STS station (needs >=1.12m)
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 12
(X-Y) gap of the magnet available for the detector replacement
from target from magnet outlet
1.0
7 m
1.4
m
1.6
m
1.6 m
1.1 m 0.77 m0.77 m
last STS station (needs >=1.12m)
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 13
Software used for the field calculation
• TOSCA finite element solver for the analysis of all magnetostatic, electrostatic and current flow problems in 3 dimensions(part of the OPERA 3D Software for electro-magnetic design by Vector Field) http://www.vectorfields.com/content/view/27/50/
• Preliminary field calculations have been performed using RADIA - multiplatform software dedicated to 3D magnetostatics computation, optimized for the design of undulators and wigglers made with permanent magnets, coils and linear/nonlinear soft magnetic materials. http://www.esrf.eu/Accelerators/Groups/InsertionDevices/Software/Radia/DocumentationInterfaced to Mathematica (http://www.wolfram.com/ ) via MathLink.
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 14
Magnet geometry under Opera 3D
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 15
The field map “FieldMuon2”
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 16
|B|(x,y) after the magnet
10 cm after the magnet
screen edge
End of the magnetic screen
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 17
Comparison of |By| (z,y) x=0 and x=100:
MuonMagnet and Muon2a
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 18
Comparison of |B| (z,y) x=0 and x=100:
MuonMagnet and Muon2a
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 19
The Geant geometry created for cbmroot framework
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 20
“magnet_muon2.geo” & “sts_standard.geo”
0.5 m
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 21
Option: Muon2 -> Muon2a
The study: the magnet length along Z axis was decreased to 20 cm
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 22
Comparison of |By| and |B| (z,y) x=0: Muon2 and Muon2a
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 23
By(z) for Muon2 (blue) and Muon2a (green)
Field Integral [Tm] for Muon2 and
Muon2a:
[-50,50]: (2) 1.21699 (2a) 1.09416
[-30,70]: (2) 1.18609 (2a) 1.0205
[-20,80]: (2) 1.13681 (2a) 0.952771
[-10,90]: (2) 1.06949 (2a) 0.871026
[10,110]: (2) 0.896442
Elena Litvinenko CBM Collaboration Meeting 29 February 2008 24
Conclusion
• The engineering design of the window-frame dipole magnet for CBM on the basis of superconducting winding with indirect cooling is proposed.
• The proposed magnet yoke construction ensures the formation of the magnetic field in the gap which corresponds to CBM requirements.
• The cryostat design with indirect cooling system for windings with using liquid helium and nitric is proposed.
• Weight of the magnet is about 80 tons (the basement is not included ), and the flow rate of helium should be about 7 liters per hour.
• The windings can be produced in Dubna, and the yoke - in Kramatorsk.
• Magnet meets the requirements laid down in the draft, which, however, were slightly overstated for the integral of the field.
• The design of the magnet yoke (and cryostat) allows for a change of certain sizes while maintaining the required angular acceptance and retention integral field at 1 Tm.
• The corresponding field map and the Geant geometry for this magnet were created and can be used under cbmroot framework.