MICE/MuCool Coupling Magnet at HIT Technical Progress

MICE/MuCool Coupling Magnets

-1-2009-11-04 to 07, CM25, RAL/UK WANG, LI

MICE/MuCool Coupling Magnet at HITMICE/MuCool Coupling Magnet at HIT

Technical ProgressTechnical Progress

WANG, LiWANG, Li

MICE Group, ICST/HITMICE Group, ICST/HIT

Shanghai Institute of Applied Physics, CASShanghai Institute of Applied Physics, CAS



Contents

• Mandrels and Cover Plates for 3 coupling magnets

• Conductor Slices from the QiHuan Company

• Vacuum Chamber & Interface w/RF cavities

• Heat loads and Available Cooling Capacity

• Coupling Magnet Double-Band Support



Mandrels and Cover Plates for 3 coupling magnets

• The 6061-T6 Al mandrel fabrication is changed from welded plates to a

forging because the heat treatment process of welded mandrel is hard to

realize using currently available ovens in China.

• 3 forged mandrels and 2 forged cover plates were contracted out to

QiHuan Corp. in Beijing at the end of October (Fabrication of one cover

plate for the MuCool magnet has been done). The first MuCool mandrel is

expected around the middle of February 2010, which means the MuCool

coil winding can only start at the end of February 2010 if without having

large coil test. The other two MICE mandrels are expected in April or May,

2010.

• There is an additional cost of 100k YuanRMB for the MuCool mandrel. The

welded mandrel with cost of 70k YuanRMB has to be abandoned. (This is a

potential funding issue.)



Welded Mandrel Already Fabricated

Heat treatment is required to make the mandrel strong enough



Strength of forged 6061-T6Al mandrel • 遵循中华人民共和国有色金属行业标准 YS/T479-2005《一般工业用铝及铝合金锻件》；

Conform to the Chinese standard YS/T479-2005 on forged Al and Al alloy.

• 自由锻件（胎膜）的尺寸及偏差符合供需双方签订的图样或合同规定。截面积不大于165000mm^2的自由锻件，室温力学性能符合 YS/T479-2005- 表 4 的规定。 The material strength at room temp. can reach the value as the below table in YS/T479-2005.

Longitudinal Transverse Radial

Thick



Conductor Slices from the QiHuan Company

The training of coil winding technique for QiHuan by ICST was done by the end of this July.

The QiHuan company submitted three 1-meter long conductor splices to be tested at LBNL. All the splices submitted had resistances that were less than 0.6 n at 1 T. The splice fabricated by ICST were also entirely satisfactory in that they ran from 0.7 to 1.3 n. The change between the ICST splices and the QiHuan splices is not fully understood.

The QiHuan splices were tested in magnetic fields from 0 to 5 T. The 0 field splices had a much smaller resistance because the solder was superconducting at that field. The solder selected was the Sn-Pb eutectic Solder, which tested very well in the splice tests.



Vacuum Chamber & Interface w/RF cavities

Discussion among HIT, QiHuan and LBNL recently:

Tolerance Required (Technical

Agreement )

Achievable for MICE coupling

magnets

Achievable for MuCool coupling magnet

The longitudinal position of the cryostat center should be the same as the coil center

±0.5 mm ±1.0 mm ±5.0 mm

The coupling solenoid cold mass central axis shall be co-axial with the cryostat vacuum vessel axis

± 0.3 mm ± 1.0 mm ±5.0 mm

The maximum allowable tilt of the cold mass axis (the magnetic axis) with respect to the axis of the warm bore tube

±0.001 radian (±0.057 degree)

±0.004 radian (±0.228 degree)

±0.35 degree

• Is tolerance is acceptable for the MICE cooling channel?

• Does the MuCool magnet need to work as back-up for the MICE cooling channel?

• Higher accuracy means a higher cost for fabrication (doubled price). For now, the cost is till within the budget, but if high accuracy required for MuCool magnet, it is beyond the budget and the procured 304SS materials for MuCool magnet vacuum chamber (~80k Yuan RMB) has to be abandoned (funding issue) !

Too HighFor MICE



Heat Loads and Available Cooling Capacity at 4.2K

HTS current leads ( Warm HTS end T = 64K) (W) 0.15

4.2K Cold mass supports (intercept T = 80K) (W) 0.35

Radiation heat to 4.2K cold mass (Shield T = 100K) (W) 0.50

Instrumentation Wires (~120 wires) (W) 0.20

Neck tubes with 0.2W from each drop-in cooler (W) 0.52

14 Superconducting Splices @ 10 n, per splice and 210 A (W) 0.01

Sub-Total (W) 1.73

50 percent Contingency (W) 0.87

Total with Contingency (W) 2.60

Is the contingency adequate?

A single Cryomech PT415 cooler generates, 1.5W/4.2K, 50Hz with the first stage at 55 K.

Greatestuncertaint

y



Copper leads from 300 K (W) 19.3

Cold mass supports (W) 9.9

Radiation Heat to the Shields (W) 10.0

Instrumentation wires (W) 1.2

Neck Tubes and Cooler Tubes (W) 8.8

Heat shield supports (W) 4.6

Sub-total (W) 54.1

50 Percent Contingency (W) 27.1

Total Heat Load with Contingency (W) 81.2

Heat Loads and Available Cooling Capacity on the Cooler First Stage at 60K

Note: A Cryomech PT415, is good for 60W at 55 K for the cooler first stage.

Greatestuncertainty



Top he vessel

Cooling tubing

Heat shield

Vacuum vessel

Banding

Coil

End plate

Bobbin

Cover plate

10mm

18mm

Tight space for MLI



RFCC coupler tube

CM vacuum vessel

MLI

Thermal shield

Cold mass

The tight space will lead to difficulty in cryostat assembly and an increase in the heat leak locally in the five places where the couplers and vacuum pump port come out of the

vacuum vessel.

The problem is the potential for a larger radiation heat leak at 4.2 K into the cold mass. This has been an ongoing problem.



300K-60K Band

Rod End

Pin

Thermal Intercept

Clevis

60K-4.2K BandBracket

Base Plate

Coupling Magnet Double-Band Support



Cold Mass Support Assembly

• Due to possible shipping loads of 2.5g during long distance transport, the design

force of the cold mass support assembly was increased from 127 kN to 200 kN,

the single-band support was updated to the double-band support considering

tight space and restricted heat leakage requirement through the bands.

• The small angle (<100 due to the magnet design) is another challenge in the

cryostat assembly.

Angle <10o



Concluding Technical Comments

The mandrel will be changed from a welded plate mandrel to a forging

because of heat treatment of the welded mandrel is a problem. The

forging has adequate strength in all directions.

The margins for coil placement in the cryostat need to be reviewed

further.

Small insulation spaces around the couplers and on the cryostat inner

bore can cause a higher heat leak at 4.2 K. This is still a concern.

The cold mass support design was changed because of the shipping

loads. The small angle (<10o due to the magnet design) is another

challenge in the cryostat assembly. The conservative design of the

cold mass supports might allow the support angle to be changed.



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MICE/MuCool Coupling Magnet at HIT Technical Progress

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