12 March 2006 NFMCC Meeting, IIT, Chicago 1

Progress on the MICECooling Channel and Tracker

Magnets

Michael A. Green

Lawrence Berkeley Laboratory

12 March 2006 NFMCC Meeting, IIT, Chicago 2

MICE Channel with the Trackers

Drawing by S. Q. Yang, Oxford University

Tracker Module 1

Tracker Module 2

AFC Module 1 AFC Module 3

AFC Module 2

RFCC Module 1

RFCC Module 1

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Summary of the MICE Magnet Changessince the last NFMCC Meeting

• The baseline magnet lattice has been changed slightly. There may be other small changes in the tracker magnet system.

• Since the NFMCC meeting, there have been no changes in the AFC magnet and the coupling magnet, but discussions with vendors suggest that changes may be needed.

• The tracker solenoid has been designed and a specification has been written. The RFP will go out soon.

• As a result of discussions with magnet vendors, the magnet design may move toward indirect cooling with LHe in pipes.

• Further work has been done on the worst case longitudinal magnetic forces in MICE.

• The field at the cooler determines what type of cooler to use.

12 March 2006 NFMCC Meeting, IIT, Chicago 4

Courtesy of S. Q. Yang, Oxford University

The MICE AFC Module

12 March 2006 NFMCC Meeting, IIT, Chicago 5

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

The Center of the MICE AFC Module

Courtesy of S. Q. Yang, Oxford University

12 March 2006 NFMCC Meeting, IIT, Chicago 6

The Focusing Magnet

AFC Magnet October 27, 2005

Aspects of the AFC Magnet

The cooling of the AFC magnet will probably change from liquid on the outside of the coils to liquid in tubes attached to the coils. This changes some of the pressure vessel code design issues.

The HTS leads will be located in the cryostat vacuum space. The copper lead design current is 250 A.

The AFC magnet cold mass support system is designed for 50 tons in the longitudinal direction.

Drawing by S. Q. Yang, Oxford University

12 March 2006 NFMCC Meeting, IIT, Chicago 7

Coupling Magnet

Cavity RF Coupler

Dished Be Window

RF Cavity

Module Vacuum Vessel

Vacuum PumpMagnet Vacuum Vessel

The MICE RFCC Module

Courtesy of S. Q. Yang, Oxford University

12 March 2006 NFMCC Meeting, IIT, Chicago 8

The Coupling Magnet

The cooling of the coupling magnet May change from liquid helium on the outside of the coils to liquid helium in tubes attached to the coils. This changes some of the pressure vessel code design issues.

The HTS leads will be located in the cryostat vacuum space. The copper lead design current is 230 A.

The magnet cold mass support system is designed for a longitudinal force of 50 tons.

Aspects of the Coupling Magnet

Quarter Section of RFCC Module

Drawing by S. Q. Yang, Oxford University

12 March 2006 NFMCC Meeting, IIT, Chicago 9

End Coil 2

Center Coil

Match Coil 1

End Coil 1

Match Coil 2

Coil Cover

Liquid Helium Space

490 mm

690 mm

2544 mm

Coil Spacer

Tracker Solenoid Cold Mass

Courtesy of S. Q. Yang, Oxford University

12 March 2006 NFMCC Meeting, IIT, Chicago 10

Tracker Solenoid 50 Ton Longitudinal Force Cold Mass Support System

300 K Support End

60 K Support Intercept

Support Band

4 K Support End

Cold Mass Assembly

Courtesy of S. Q. Yang, Oxford University

12 March 2006 NFMCC Meeting, IIT, Chicago 11

Tracker Magnet Cold Mass, CoolersCryogenic Distribution System

Magnet Cooler

Condenser Box

Cold Mass Support

Helium Gas PipeLiquid Helium Pipe

Cold Mass Assembly

Magnet Leads

Courtesy of S. Q. Yang, Oxford University

12 March 2006 NFMCC Meeting, IIT, Chicago 12

Changes in the Cryogenic System

• The high temperature superconductor (HTS) leads may have to operate in a vacuum (depends the on type of lead). The lead vacuum-tight feed through problem is not trivial.

• A number of the vendors suggest that the MICE coils should be cooled indirectly (using liquid helium in tubes). This is OK as long as the tube area is large enough.

• Changing from having a liquid reservoir in the cold mass assembly to liquid helium in tubes will change the pressure vessel code design of the magnet cold mass. The only part of the helium system that comes under the pressure vessel code is the condenser box at the bottom of the magnet coolers.

12 March 2006 NFMCC Meeting, IIT, Chicago 13

Power Supply Specification

• The power supply design current is +300 A at ±10 V. This is a two quadrant power supply with current regulation of better than ±0.01 percent over a current range from 50 A to 275 A. The highest currents are in tracker coils. There will be be at least six of these power supplies.

• The small power supply design current is ±50 A at ±5 V. This is a four quadrant power supply with current regulation of better than ±0.03 percent over a range of currents from 5 to 45 A. There will be at least four of these power supplies.

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PSPower Supply±10 V, 0 to 300 A

Total Inductance from 304 H to 416 H

PSPower Supply±10 V, 300 A

Coupling MagnetMandrelCold DiodeCold ResistorInductance = 563 H

Focusing and Coupling magnet Hookup

12 March 2006 NFMCC Meeting, IIT, Chicago 15

Power Supply±10 V, 300 A

Power Supply±5 V, ±50 A

PSPSPSPSPSPSPSPower Supply±5 V, ±50 A

Tracker Magnet Hookup

M1 M1M2 M2 E1E1 E2E2 C C

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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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Forces with MICE Magnet Quenches

MagnetBaselineMICE

Both TrackerMagnets Normal

One CouplingMagnet Normal

Three FocusMagnets Normal

Detector 25.5 -0- 40.6 -14.7

End Focusing -18.8 21.4 -40.3 -0-

Coupling -8.8 -15.2 -0- -8.7

Center Focusing 0 0 21.5 -0-

Coupling 8.8 15.2 -7.1 8.7

End Focusing 18.8 -21.4 18.6 -0-

Detector -25.5 -0- -33.3 14.7

See MICE Note 107 with the magnet lattice of August 2004.

The three focusing magnets will quench together.

Both Tracking magnets quench together.Only one coupling magnet will quench.

12 March 2006 NFMCC Meeting, IIT, Chicago 18

“Hey dummy, you reversed the leads 1.”

MagnetBaselineMICE

1 CouplingCoil Reversed

2 CouplingCoils Reversed

3 Focus CoilsReversed

Detector 10.5 10.2 22.0 -11.3

End Focusing -3.0 -3.4 -47.0 3.0

Coupling -15.6 26.8 15.6 -14.1

Center Focusing 0 -43.0 -0- -0-

Coupling 15.6 -15.6 -15.6 14.1

End Focusing 3.0 47.0 47.0 -3.0

Detector -10.5 -22.0 -22.0 11.3

Baseline MICE Lattice as of March 2006, when p = 200 MeV/c and = 420 mm.

The highest forces are in the focusing coils when the coupling coil leads are reversed.

12 March 2006 NFMCC Meeting, IIT, Chicago 19

“Hey dummy, you reversed the leads 2.”

MagnetBaselineMICE

Both M1 CoilsReversed

Both M2 CoilsReversed

SpectrometersReversed

Detector 10.5 -25.4 -6.7 11.9

End Focusing -3.0 38.0 2.0 1.0

Coupling -15.6 12.7 -17.7 -20.8

Center Focusing -0- -0- -0- -0-

Coupling 15.6 8.8 17.7 20.8

End Focusing 3.0 -38.0 -2.0 -1.0

Detector -10.5 25.4 6.7 -11.9

Baseline MICE Lattice as of March 2006, when p = 200 MeV/c and = 420 mm.

The highest forces are in the end focusing coils when the M1 leads are reversed.

12 March 2006 NFMCC Meeting, IIT, Chicago 20

Peak Longitudinal Forces

• The peak longitudinal forces on the focus coils will occur when p = 240 MeV and = 420 mm in the flip mode, with the leads reversed. The peak force is about 68 tons on the end focusing magnets, when one or both coupling magnets are reversed. When the M1 coils are reversed, the peak force on the end focus coils is about 54 tons in the flip mode. The MICE magnet polarity must be checked before going to high momenta (currents in the coils).

• In the non-flip mode the peak force on the focusing magnet is about 46 tons with the leads reversed. Similar forces may be found in the tracker magnets. More work is needed to show what the peak forces are in all of the magnets.

12 March 2006 NFMCC Meeting, IIT, Chicago 21

Axial Field outside around the Tracker

Cooler LocationB = 0.085 to 0.145 T

From Holger Witte at Oxford University

VLPC Cooler LocationB = 0.02 to 0.045 T

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Radial Field outside around the Tracker

Cooler LocationB = 0.085 to 0.145 T

From Holger Witte at Oxford University

VLPC Cooler LocationB = 0.02 to 0.045 T

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Radial Field outside the AFC Module

Magnet & AbsorberCooler LocationB = 0.35 to 0.5 T

From Holger Witte at Oxford University

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Axial Field outside the RFCC Module

Cooler LocationB = 1.0 to 2.0 T

From Holger Witte at Oxford University

Rotary Valve LocationB = ~0 to 0.2 T

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Comments on Cooler Location and theType of Cooler to be used

• The field at the coolers for the tracker magnet is about ~0.1 T. If the coolers are moved out about 0.1 meters, GM coolers can be used for this magnet.

• The field at the coolers for the AFC module is about 0.3 to 0.5 T. This is too high for using a GM cooler without a large iron shield. Use pulse tube coolers with shielded rotary slide valves.

• The field at the cooler for the RFCC module is ~1.5 T. This is too high for a GM cooler. Use a pulse tube cooler with a remote shielded rotary slide valve.

• The VLPC coolers can be GM coolers, because the field is less than 0.05 T

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Concluding Comments

• It appears that indirect cooling (liquid helium in tubes) will be used for all of the MICE magnets.

• The performance of the match coils for the MICE tracker magnet is not understood. The actual vendor magnet design will be determine the final match coil operating currents.

• The peak longitudinal forces occur at 240 MeV/c in the flip mode. These forces occur in the focusing magnets when the coupling coil leads are reversed. The coil lead polarity must be checked before going to high currents.

• Two types of power supplies will be used on MICE. The large supply is 300 A at ±10 V. The small supply is ±50 A at ±5 V.

• Pulse tube coolers will be used on all of the MICE magnets.