Progress on the MICE Cooling Channel Magnets

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Progress on the MICE Cooling Channel Magnets

• Michael A. Green
• Lawrence Berkeley National Laboratory
• 28 June 2005

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3D View of the MICE Cooling Channel
Coupling Magnet Cryostat
AFC Module
RFCC Module
Courtesy of S. Yang Oxford University
3
Three Quarter Section View of the MICE Cooling
Channel
Courtesy of S. Yang Oxford University
Coupling Coil
Focusing Magnet Coil
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Half Section View of theMICE Cooling Channel
Liquid Hydrogen Absorber
Focusing Magnet Coil
201 MHz RF Cavities
Coupling Coil
Courtesy of S. Yang Oxford University
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Cooling Channel Magnet Progress

• The cooling channel consists of three AFC modules
  and two RFCC modules.
• This report will discuss the progress made since
  the last meeting on the focusing magnet and the
  coupling magnet.
• Progress on the tracker magnet (detector magnet)
  will not be presented. This information was
  presented on June 27th.

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Focusing Magnet
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The MICE AFC Module
Courtesy of S. Yang Oxford University
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The Center of the MICE AFC Module
Gas He Pipe
Coil Cover Plate
S/C Coil 1
S/C Coil 2
LH2 Absorber
Hydrogen Window
LH2 Pipes
Safety Window
Magnet Mandrel
Liquid Helium Feed Pipe
Courtesy of S. Yang Oxford University
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The Focusing Magnet Parameters
These are the worst cases based on p 240 MeV/c
and b 420 mm
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Focusing Magnet Progress

• Progress has been made on the focusing magnet
  quench protection system and in the power system
  for the magnets.
• The quench simulations show that the focusing
  magnets can be passively quenched without a
  formal quench protection system.
• The three focusing magnets can be connected in
  series. External diodes and resistors are used
  to control the voltages across the coils.

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Focusing Magnet QuenchOne Magnet 3 in Series
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250 A Focusing Magnet QuenchFlip Mode Non-flip
Mode
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Focusing Magnet Mandrel Tafter a Quench in the
Flip Mode

• Max T 51.9 K
• Min T 4.41 K
• Quench Time 4 s
• Istart 250.8 A
• 0.80
• p 240 MeV/c
• b 420 mm

Courtesy of H. Witte Oxford University
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Focusing Magnet Mandrel Tafter a Quench in the
Non-flip Mode

• Max T 41.7 K
• Min T 4.69 K
• Quench Time 4 s
• Istart 130.3 A
• 0.80
• p 240 MeV/c
• b 420 mm

Courtesy of H. Witte Oxford University
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Focusing Magnet Mandrel Hot Spot Tas a Function
of Time

• Max T 51.9 K
• Min T 4.41 K
• Quench Time 4 s
• Istart 250.8 A
• 0.80
• p 240 MeV/c
• b 420 mm

Quench back occurs.
Courtesy of H. Witte Oxford University
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Focusing Magnet Power System
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Coupling Magnet
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The MICE RFCC Module
Courtesy of S. Yang Oxford University
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Coupling Magnet Parameters
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Coupling Magnet Progress

• Progress has been made on the coupling magnet
  quench protection system and in the power system
  for the magnets.
• The quench simulations show that the coupling
  magnets can be passively quenched without a
  formal quench protection system.
• The two coupling magnets can be connected in
  series, but it may be better to power the two
  magnets separately. Cold diodes and resistors
  are used to control the voltages within the coils.

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Coupling Magnet QuenchOne Two Magnets in Series
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Coupling Magnet Quench6061-T6 and 1100-O Mandrels
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Coupling Magnet Mandrel Tafter a Quench in the
Flip Mode

• Max T 83.9 K
• Min T 4.21 K
• Quench Time 5 s
• 0.92
• p 240 MeV/c
• b 420 mm

Courtesy of H. Witte Oxford University
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Coupling Magnet Mandrel Hot Spot Tas a Function
of Time

• Max T 83.9 K
• Min T 4.21 K
• Quench Time 5 s
• 0.92
• p 240 MeV/c
• b 420 mm

Quench back occurs.
Courtesy of H. Witte Oxford University
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Coupling Magnet Power System
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Coupling between Magnet Circuits
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Coupling Coefficients between Coils
Magnet Circuit Self Inductance and the Mutual
Inductances in the Flip Mode
Magnet Circuit Self Inductance and the Mutual
Inductance in the Non-flip Mode
Courtesy of H. Witte Oxford University
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Conclusions from the Self and MutualInductance
Calculations

• Every magnet circuit in MICE is coupled to every
  other magnet circuit in MICE.
• The charging or discharging of one magnet circuit
  will affect every other magnet circuit, but the
  power supplies can handle the effect.
• A quench of one magnet circuit will not drive
  other magnets normal by changing the currents too
  much. AC losses induced by a quench do not
  appear to be a factor, except from mandrel
  heating.

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Coupling between Magnet Coil Circuits and other
Magnet Mandrels
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Currents for Various Cases and theCoupling
Coefficients
Coil Currents for Various Cases where p 240
MeV/c and b 420 mm
Coil to Mandrel Coupling Coefficients for Various
Cases
Courtesy of H. Witte Oxford University
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Heating of the Coupling Mandrelby a Focusing
Quench (Flip Mode)
Courtesy of H. Witte Oxford University

• Max T 4.45 K
• Min T 4.41 K
• Quench Time 4
• 0.0018
• p 240 MeV/c
• b 420 mm

A quench of the focusing magnet circuit is
unlikely to quench the coupling magnet in the
flip mode.
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Heating of the Coupling Mandrel by a Focusing
Quench (Non-flip Mode)
Courtesy of H. Witte Oxford University

• Max T 4.76 K
• Min T 4.69 K
• Quench Time 4 s
• 0.0137
• p 240 MeV/c
• b 420 mm

A quench of the focusing magnet circuit may
quench the coupling magnet in the non-flip mode,
at high momenta.
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Heating of the Focusing Mandrel by a Coupling
Quench (Flip Mode)
Courtesy of H. Witte Oxford University

• Max T 6.30 K
• Min T 4.22 K
• Quench Time 5 s
• 0.0813
• p 240 MeV/c
• b 420 mm

A quench of the coupling magnet circuit is likely
to quench the focusing magnet in either mode.
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Coupling Coefficients between Magnet Circuits and
Various Mandrels
Courtesy of H. Witte Oxford University
The quench of a cooling channel magnet circuit is
unlikely to cause a quench of a tracker magnet.
A tracker magnet quench wont quench the channel
magnets.
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Conclusions from the Magnet Coupling Calculations

• A quench of a focusing magnet is unlikely to
  quench any other magnet except the coupling
  magnet at high muon momenta in the non-flip mode.
• A quench of a coupling magnet is likely to quench
  the focusing magnet except at low muon momenta.
  A coupling magnet quench will not quench the
  tracking magnet.
• A quench of the tracker magnet is unlikely to
  quench any of the other magnets in MICE.

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Concluding Comments

• Engineering progress has been made on all of the
  MICE magnets and their sub-systems.
• Quench calculations show that the MICE focusing
  and coupling magnets will quench safely. It is
  probable that the detector magnets will also
  quench safely. This will be verified before the
  next meeting.
• A coupling magnet quench will cause the focusing
  magnet to quench, but a quench of the other
  magnets is unlikely to cause a quench of other
  magnets in MICE.