Helical Solenoids for Helical Cooling Channels

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Helical Solenoids for Helical Cooling Channels

• Mauricio Lopes

Fermilab 04/23/2009
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Outline

• Introduction
• HCC parameters
• High field section case study
• Superconductor choice
• Calculation process
• Geometry vs. Performance
• Correction coil
• Conductor improvement
• Coil optimization
• Grading

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Introduction
Helical cooling channels (HCC) based on a magnet
system with superimposed solenoid and helical
dipole and gradient, and a pressurized gas
absorber in the aperture has been proposed to
achieve the high efficiency of 6D muon beam
cooling.
The total phase space reduction of muon beams is
on the level of105-106.
To reduce the equilibrium emittance the cooling
channel was divided into several sections and
each consequent section has a smaller aperture
and stronger magnetic fields.
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Particle dynamics in HCC
Y. Derbenev and R. Johnson, Six-Dimensional
Muon Cooling Using a Homogeneous Absorber, Phys.
Rev. ST AB, 8, 041002 (2005)
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Particle dynamics in HCC
Dispersion factor
Important parameters to design HCC
Stability condition is
Y. Derbenev and R. Johnson, Six-Dimensional
Muon Cooling Using a Homogeneous Absorber, Phys.
Rev. ST AB, 8, 041002 (2005)
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Helical cooling channel parameters
Bcoil 21 T
operation margin
K. Yonehara et al, Studies of a Gas-Filled
Helical Muon Cooling Channel, Proc. of EPAC2006,
Edinburgh, Scotland.
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Superconductor choice
D. Turrioni et al., Study of HTS Wires at High
Magnetic Fields, ASC2008, Chicago, 2008
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Straight Solenoid Optimization Process
I (kA)
?
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Helical Solenoid Optimization Process
?
I (kA)
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Helical Solenoid Optimization Process
ID fixed
Current is adjusted to keep Bz constant
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Geometry vs. Performance
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Geometry vs. Performance
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Correction system
Bz Bt G
I (kA)
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Correction system
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Conductor improvement
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Coil grading
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Coil grading
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Coil grading
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Coil grading
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Coil grading
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Hybrid
HTS
Nb3Sn
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Hybrid
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Hybrid
Gapmin d
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Hybrid
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Hybrid coil grading
g represents a 40 mm gap
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Short vs. long model

• Its planned to build 4 to 5 HTS coils not for
  field performance but to address manufacture
  issues

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Sketch of the conceptual model
Acknowledgment M. Yu
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Open questions

• Winding
• Hard bend
• Easy bend

• HTS material election
• BSCCO
• YBCO

• Degradation

• Mechanical support
• No outer support (?)

• Reduce support thickness to have the same stress
  levels as in the longer magnet

• Assembly procedure for a hybrid model

• Quench protection
• BSCCO has low quench propagation velocity (a few
  cm/s)

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Conclusions

• An extensive study of HS was performed which
  give us the limits of this system.

• Feedback for the beam dynamics/cooling
  calculations.

• Motivation for the material science (larger bore
  implies in better conductors).

• It was demonstrated that it is possible to match
  all the 3 components relying on the geometry and
  one correction system (SS).

• Two knobs to adjust Bz and Bt independently,
  but none for G.

• If a third knob is needed, it would lead to a
  more complicated correction systems.

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Conclusions

• Coil grading could save up to 23 HTS coil
  volume without affecting the overall performance.

• A hybrid system could be used to save HTS
  material (in a particular case 60 ) but does not
  necessarily makes the magnet system smaller.

• There is a minimum gap between the coils to
  allow the system assembly but the final gap size
  is under study (support structure dimensions).

• Larger gap impacts the magnet overall
  performance.

• A short models is under development and it is
  supported by Fermilab and Muons, Inc. (SBIR)

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Acknowledgments
M. Alsharo N. Andreev E. Barzi R. Johnson S.
Kahn V.S. Kashikhin V.V. Kashikhin M. Lamm V.
Lombardo A. Makarov G. Norcia D. Turrioni K.
Yonehara M. Yu A. Zlobin