ADJUSTABLE STRONG PERMANENT MAGNET

FOR FINAL FOCUS QUADRUPOLE

T. MIHARA, Y.IWASHITA Kyoto UniversityM. KUMADA N.I.R.S.C.M.Spencer S.L.A.C.

The first prototype of “superstrong” Permanent Magnet

Quad.

Integrated strength GL=28.5T (29.7T by calc.) 　　　　　　　　　　　　 magnet size. 10cm

bore 1.4cmField gradient is about 300T/m

PHOTOCut plane view

Axial view

PM

Soft iron

dzdr

dBGL

Double Ring Structure –Adjustable PMQ-

The double ring structure

PMQ is split into inner ring and outer ring. Only the outer ring is rotated 90 around the beam axis to vary the focal strength.

ON

Permanent magnet

Pole material

OFF

First Quadrant shows the flux plot.

Definition of “Switched-On” Length16 series of outer ring

switchingNo. 8cm4cm2cm1cm “Switched- on” length

1 ON ON ON ON 15cm2 ON ON ON OFF 14cm3 ON ON OFF ON 13cm4 ON ON OFF OFF 12cm5 ON OFF ON ON 11cm6 ON OFF ON OFF 10cm7 ON OFF OFF ON 9cm8 ON OFF OFF OFF 8cm9 OFF ON ON ON 7cm10 OFF ON ON OFF 6cm11 OFF ON OFF ON 5cm12 OFF ON OFF OFF 4cm13 OFF OFF ON ON 3cm14 OFF OFF ON OFF 2cm15 OFF OFF OFF ON 1cm16 OFF OFF OFF OFF 0cm

ON

8cm 4cm1cm2cmCut Plane View

Design Parameter of the Adjustable PMQ

Bore 1.0cm

Outer radius of the inner

ring6.0cm

Inner radius ofouter rings

6.6cm

Outer radius outer rings.

10cm

Mechanical length

23cm

Outer ring size along the axis

1.0cm,2.0.m,4.0cm,8.0cm

Max. integrated strength

25.1T(28T)

Min. integrated strength

4.7T(7T)

step 1.4T

pole Vanadium permendur

Inner ring

magnet

NEOMAX38AH(Br=1.23T,iHc=28kOe)

Outer ring

magnet

NEOMAX44H(Br=1.33T,iHc=16kOe)

material

dimensions

strength

An adjustable PMQ

Outgoing beam line is 7cm distant from incoming beam line.

Outer ring is rotated by DC motors.

Measurement with Rotation Coil @SLAC

Rotating Coil

Temperature　21.7±0.2C.

Preliminary data:

• integrated strength

• center shift by changing strength

• skew rotation angle by changing strength

8cm 4cm1cm2cm

Strength variability

Integrated strength is proportional to the “switched-on ” length

It allows us simple adjustment

This PMQ can generates GL 1/5 of the maximum GL.

0

5

10

15

20

25

0 5 10 15

Integratedstrength

"Switched-on" length [cm]In

tegr

ated

Gra

dien

t[T]

Magnetic Center Shift when Integrated Gradient is Changed

X center and Y center shift when GL is changed. Mechanical adjustment may reduce shift.

-0.05-0.04-0.03-0.02-0.01

00.010.020.030.040.050.060.070.08

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

"Switched-on" length

Skew

rot

atio

n an

gle

Skew rotation angle by changing strength

Fig. shows the skew rotation angle as the function of switched-on length.

This will be reduced by adjustment.

1cm

_on

2cm

_on

4cm

_on

8cm

_on 1,2

,8cm

_on

strongest

weake

st

Y=0.01x

Y=0.0085x+1.365

Options for Various L* & X’ing Angles

NBS (For Head on)

MBS (For 7mrad)

SBS (For 2mrad)

LBS(2nd

prototype) (For 20mrad)

NBS=No Beam Separation, SBS=Small Beam SeparationMBS=Medium Beam Separation, LBS=Large Beam Separation

Q-size 160mm 160mm 160mm 100mmGrad. With

20mm bore212T/m(max)

-23T/m (min)

175T/m (max)

-77T/m (min)

208T/m(max)

26T/m (min)

186T/m(max)

31T/m(min)

Grad. With 14mm bore

296T/m 242T/m 282T/m 272T/m

Summary• “Double ring ” Adjustable PMQ was

fabricated. This PMQ generates GL from 3.48T to 24.2T by 1.4T step.

• Magnetic center shift was measured; good reproducibility was observed.

• Measurement of Skew rotation angle shows the relative rotations of the rings.

• Shifts and rotations will be adjusted.• Configurations can be changed to

meet with various beam separations .