Q1 for JLAB’s 12 Gev/c Super High Momentum SpectrometerS.R. Lassiter, P.B. Brindza, M. J. Fowler, S.R. Milward, P. Penfold, R. Locke

Q1

SHMS

HMS

Q2Q3

BenderDipole

Abstract— The reference design for the first Quadrupole magnet of TJNAF’s Super High Momentum Spectrometer (SHMS), Q1, is presented. The SHMS is a dQQQD design that will be capable of resolve particles up to 11 Gev/c in momentum. Q1 follows the successful design of the High Momentum Spectrometer’s (HMS) Q1, that of an elliptically shaped super ferric yoke, conformal mapped window frame coil, bath cooled coil design. The primary differences between the two designs being in the choice of superconducting cable and an overall longer magnet length. A single stack of surplus SSC Rutherford NbTi cable replaces the original four stack copper stabilized conductor used in the HMS’s Q1. The Q1 will have warm bore diameter of 400 mm, produce field gradients up to 9.1 T/m with an effective length of 2.14 m. Test coil windings progress will be given as well as reports on forces, conductor stability and energy margins.

Parameter Quantity

Conductor Dimensions11.688 x 1.093

mm

Filament size 0.402 m

Cu:SC Ratio ```

Ic (4.5K and 5.3T) 7846

Ic / Io (4.5K and 5.3T) 2.46

Kilo Amp Turns /Pole 255 A.T

Critical Current Margin 4,659 A

Kapton Thickness 0.102 mm

B-stage Epoxy Thickness 0.127 mm

Voltage Discharge 500 V

Hot Spot temperature 41 K

Parameter Quantity

Pole Radius 0.250 m

Warm Bore 0.402 m

Axial Cryostat Length 2.2 m

Yoke Length 2.03 m

Current Density 18,100 A.T/cm2

Kilo Amp Turns /Pole 255 A.T

Turns / pole 80

Operating Current 3187.1 A

Stored Energy 0.628 MJ

Inductance 123.7 mH

Magnet Weight 18 tons

Parameter` Quantity

Gradient Max 9.15 T/m

Effective Field Length 2.151 m

Peak Yoke Field 4.61 T

Peak Coil Field 2.7 T

Field at Pole (R=0.25 m) 2.27 T

Momentum Range 2 to 11 Gev/c

Integral Harmonic N=4% of N=2

-.04 to -1.02 %

Integral Harmonic N=6 % of N=2

-2.21 to 0.21%

Integral Harmonic N=10 % of N=2

-0.32 to -.10 %

Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DOE-AC05-060R23177.

SHMS Parameters

SHMS_Q1 Load Line

0

5000

10000

15000

20000

25000

0 1 2 3 4 5 6 7 8 9

Field [T]

Ic

[A]

Tosca

Fitted

4.42 K

8.3 K

Measured

Q1

Magneto-Static Results

2.32 m

Yoke length

Cold Mass Side ViewCurrent Lead End

Cold Mass Assembly

Notch for beamline extends to Helium Outer vessel.

Ø 0.40 m

Warm Bore

Cross Sectional View

Outer Vacuum shell

Outer He Vessel

SS Yoke Band

Inner He Cylinder

Ln2 Shields / MLI Not Shown

Quadrant view of yoke lamination and Coil clamping Fixture

80 Turns of Rutherford cable

Coil clamping/tensioning Fixture

Mechanical Configuration

Photos from Scientific Magnets LTD.

Trail Winding

Burnout Proof 5KA Current Leads

The current leads will have a 9 W heat load to the 4K budget at full current.

Scientific Magnetics studied the mechanical implications of increasing the magnet length by 15% over the original HMS Q1 and determined that sufficient margins existed to safely handle the expected loads.

Magnetic Forces calculated by JLAB using TOSCA and

loaded into a two dimensional FEA model. Largest stress is below 41MPa.

SHMS Q1 Harmonics

-2.50

-2.00

-1.50

-1.00

-0.50

0.00

0.50

0.0 500.0 1000.0 1500.0 2000.0 2500.0 3000.0 3500.0

Current [A]

Per

cent

age

of Q

uadr

upol

e Te

rm n=4

n=6

n=8

n=10

n=14

Integral Harmonics for the SHMS Q1Field Modulus in the Yoke and The Coil

SHMS Q1

0

2

4

6

8

10

12

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80

Z [m]

Gra

die

nt

T/m

GRADIENT: 9.105T/m

Int G.dz: 19.452(T/m).m

EFL: 2.136m

Yoke: 2.322m

Cryostat

Coil

Yoke

Field Gradient at maximum current

Yoke, Coil and Cryostat lengths are given for comparison.

Plots starts at the center of the magnet and extends out one end.

Maximum Field in the yoke occurs along the pole edges. Nominal

Field within the yoke is 2.4 T

Holes in the yoke served multiple

purposes:

1. He cooling passage.

2. Multipole tuning feature.

3. Tie bolts holes for stacking and compressing the

Yoke laminations.