ADJUSTABLE STRONG PERMANENT MAGNET FOR FINAL FOCUS QUADRUPOLE
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Transcript of ADJUSTABLE STRONG PERMANENT MAGNET FOR FINAL FOCUS QUADRUPOLE
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 .