1 Progress on the MICE Cooling Channel Magnets Michael A. Green Lawrence Berkeley National...
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Transcript of 1 Progress on the MICE Cooling Channel Magnets Michael A. Green Lawrence Berkeley National...
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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
AFC Module
RFCC Module
Coupling Magnet Cryostat
Courtesy of S. Yang Oxford University
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Three Quarter Section View of the MICE Cooling Channel
Coupling Coil
Focusing Magnet Coil
Courtesy of S. Yang Oxford University
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Half Section View of theMICE Cooling Channel
Coupling Coil
Focusing Magnet CoilLiquid Hydrogen Absorber
201 MHz RF Cavities
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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The Center of the MICE AFC Module
Magnet Mandrel
Safety Window
LH2 Pipes
Liquid Helium Feed Pipe
Gas He Pipe
Hydrogen Window
S/C Coil #1
LH2 Absorber
S/C Coil #2
Coil Cover Plate
Courtesy of S. Yang Oxford University
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The Focusing Magnet Parameters
Parameter Non-flip Flip
Coil Inner Radius (mm)Coil Thickness (mm)No. of Layers per CoilNo. Turns per Layer
2638476127
Magnet J (A mm-2)* 72.0 138.2Magnet Current (A)* 130.5 250.7Magnet Self Inductance (H) 137.4 98.6Peak Induction in Coil (T)* 5.04 7.67Magnet Stored Energy (MJ)* 1.17 3.104.2 K Temp. Margin (K)* ~2.0 ~0.6Inter-coil Z Force (MN)* 0.56 3.53
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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Current 1
Hot Spot T 1
Current 2
Hot Spot T 2
Time from Start of the Quench (s)
Magnet Current (A) and the Hot Spot Temperature (K)
Single Magnet
Three Magnets in Series
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250 A Focusing Magnet QuenchFlip Mode & Non-flip Mode
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Current 1Hot Spot T 1Current 3Hot Spot T 3
Time from the Start of the Quench (s)
Current in the Coil (A) and Hot Spot T (K)
Single Magnet Flip Mode
Single Magnet Non-flip Mode
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Focusing Magnet Mandrel Tafter a Quench in the Flip Mode
Max T = 51.9 KMin T = 4.41 KQuench Time = 4 sIstart = 250.8 A
= ~0.80p = 240 MeV/c = 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 KMin T = 4.69 KQuench Time = 4 sIstart = 130.3 A
= ~0.80p = 240 MeV/c = 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 KMin T = 4.41 KQuench Time = 4 sIstart = 250.8 A
= ~0.80p = 240 MeV/c = 420 mmQuench back occurs.
Courtesy of H. Witte Oxford University
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The MICE RFCC Module
Coupling Magnet
Cavity RF Coupler
Dished Be Window
RF Cavity
Module Vacuum Vessel
Vacuum PumpMagnet Vacuum Vessel
Courtesy of S. Yang Oxford University
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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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Current 1Hot Spot T1Current 2Hot Spot T2
Time from the Start of the Magnet Quench (s)
Magnet Current (A) and Coil Hot Spot Temperature (K)
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Coupling Magnet Quench6061-T6 and 1100-O Mandrels
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Current 1Hot Spot T1Current 3Hot Spot T3
Time after the Start of the Quench (s)
Magnet Current (A) and Hot Spot Temperature (K)
6061-T6 Mandrel (RRR = 1.9)
1100-O Mandrel (RRR = 14)
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Coupling Magnet Mandrel Tafter a Quench in the Flip Mode
Max T = 83.9 KMin T = 4.21 KQuench Time = 5 s
= ~0.92p = 240 MeV/c = 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 KMin T = 4.21 KQuench Time = 5 s
= ~0.92p = 240 MeV/c = 420 mmQuench back occurs.
Courtesy of H. Witte Oxford University
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Coupling Coefficients between CoilsMagnet 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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Currents for Various Cases and theCoupling Coefficients
Coil Currents for Various Cases where p = 240 MeV/c and = 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)
Max T = 4.45 KMin T = 4.41 KQuench Time = 4
= ~0.0018p = 240 MeV/c = 420 mm
A quench of the focusing magnet circuit is unlikely to quench the coupling magnet in the flip mode.
Courtesy of H. Witte Oxford University
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Heating of the Coupling Mandrel by a Focusing Quench (Non-flip Mode)
Max T = 4.76 KMin T = 4.69 KQuench Time = 4 s
= ~0.0137p = 240 MeV/c = 420 mm
A quench of the focusing magnet circuit may quench the coupling magnet in the non-flip mode, at high momenta.
Courtesy of H. Witte Oxford University
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Heating of the Focusing Mandrel by a Coupling Quench (Flip Mode)
Max T = 6.30 KMin T = 4.22 KQuench Time = 5 s
= ~0.0813p = 240 MeV/c = 420 mm
A quench of the coupling magnet circuit is likely to quench the focusing magnet in either mode.
Courtesy of H. Witte Oxford University
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Coupling Coefficients between Magnet Circuits and Various Mandrels
The quench of a cooling channel magnet circuit is unlikely to cause a quench of a tracker magnet. A tracker magnet quench won’t quench the channel magnets.
Courtesy of H. Witte Oxford University
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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.