James T Volk June 2002 1

f

Permanent Magnets forLinear Colliders

James T Volk

Fermilab

James T Volk June 2002 2

fPeople already working on Permanent magnets

SLAC Seung Rhee, Cherrill Spencer, Jim Spencer

SLAC Magnetic Measurement GroupScott Anderson, Zack Wolf

Fermilab Magnetic Measurement

Joe DiMarco

LBNLJose Alonso, Jin-Young Jung

James T Volk June 2002 3

fWhy Permanent Magnets

• No Power Supplies• No Cables• No Water Cooling• No Operating Expense• Temperature stable• Time stable• Easy to Assemble• Can be in-expensive depending on field required

and material chosen

James T Volk June 2002 4

fWhere can they be used

• Fixed energy transport lines • Bending

• Focusing

• Injection or extraction

• Storage Rings• Final Focus near or inside of detectors• Quadrupoles in the NLC• Damping Rings

James T Volk June 2002 5

fPermanent Magnets at SLAC

• SLC 72 Sextupoles made of Sm1 Co5

• SLC final focus 4 Octupoles made of SM2 Co17

• PEPII two normal and two skew Quadrupoles made of SM2 Co17

• All small Halbach style magnets

James T Volk June 2002 6

fFermilab Recycler

8 GeV transfer line: 750 m long from booster to MI

Gradient

Mirror gradientSextupole

Recycler: 8 GeV anti proton storage ring Over 500 gradient, quadrupole, and sextupole permanent magnets

Temperature stableFields adjusted to within 5 parts in 104 Harmonics 1 part in 104

Vertical and Horizontal tune within 0.001 of design

James T Volk June 2002 7

fRepresentative Dipole Technologies

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 100 200 300 400 500 600 700 800

Full gap [mm]

On

-ax

is f

ield

[T

]

NdFeB

Electromagnet

Ferrite

From Kem Robinson LBNL

James T Volk June 2002 8

fQuads for NLC

Quad

Quad

James T Volk June 2002 9

fNLC LINAC Quad Specs

Table I SpecificationsItem valueAperture 12.7 mmQuantity Length 288 324 mm

399 432 mm576 965mm

Maximum Pole tip field 0.62 Tesla for 324 mm0.80 Tesla for others

Adjustment + 0 to – 20%Temperature Stability 0.5% at 25 1 oCHigher Harmonics b3/b2 < 0.02Field Accuracy 0.5% at any field valueCenter Location Magnetic to Fiducial 0.1 mmCenter Stability 0.001 mm over range of adjustment

James T Volk June 2002 10

f

Wedge QuadRods rotate to adjust field

Pole Magnets

Tuning Rods

Wedge Magnets

Flux Return

Poles

James T Volk June 2002 11

fNLC adjustable quad on SSW stand

Quad

Stretched wire stages

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fWedge Quad Rod Turning Mechanism

Tuning Rod

May 2002 James T Volk

Pin slides in slot turning rod

James T Volk June 2002 13

fCenter shifts wedge quad

FWSQ001-6

-5.0

-4.0

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

20.5 21.5 22.5 23.5 24.5 25.5

YGdl Tesla

y c

en

ter

mic

rom

ete

rs

1st pass

2nd pass

3rd pass

James T Volk June 2002 14

fSLAC Rotating Coil Data

FWSQ001-6 at SLAC

-7.00

-6.00

-5.00

-4.00

-3.00

-2.00

-1.00

0.00

1.00

2.00

17 17.5 18 18.5 19 19.5 20 20.5

Gradient Tesla

cen

ter

shif

t m

icro

ns

X center

Y center

X max 2.5 Y max 4.5

James T Volk June 2002 15

fCounter Rotating Quadrupole

James T Volk June 2002 16

fCounter Rotating Quad Data

FSRQ001

-5-4-3-2-10123

29.5 30.5 31.7 32.8 33.9 34.7 35.5 36.1 36.6Tesla

mic

ron

s

Xcenter

Ycenter

James T Volk June 2002 17

fResults

Max Grad Tesla

Min Grad Tesla

Center Shift Microns

Corner 17.5 14.1 60.0

Wedge 1 23.7 18.4 20.0

Wedge 2 26.4 23.0 >4.0

Sliding Shunt 25.9 21.8 15.0

Rotating 36.3 30.3 4.5

Electromagnet 33.2 27.4 1.0

James T Volk June 2002 18

fIssues

• Improve center stability• Time stability• Temperature stability• Motor controls• Optimize Design• New Designs

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fLBNL & SLAC work on designing magnets (PMs and EMs)

for the damping rings

• Main Damping Ring lattices have been published with detailed requirements on all magnets

• Have 2-D model of DR quadrupoles and transport line dipoles. The Nd Iron style magnets are of reasonable size

• Investigated the Nd Iron quads, with rotating rods to generate the +/-10% adjustability, in more detail to see if they could meet all the requirements.

• Jin-Young Jung (LBNL) used TOSCA to make a 3-D model of damping ring magnets

James T Volk June 2002 20

fTOSCA model of ¼ Neo quad with a steel end plate

James T Volk June 2002 21

fRadiation Damage Summary

Sample Alloy Type ofIrradiation

MaximumDose Grad

Remanence loss%

HckOe

HcikOe

CERN 1983 (6)RECOMA 20 RECo5 400 GeV protons 9.70 -42.70 8.8 30.0VACOMAX 200 SmCo5 10.400 -106.10 8.9-9.5 12.5-19.0KOERMAX 60 SmCo5 11.400 -24.20Krupp WIDIA Sm2Co17 10.500 -2.60

TRIUMPH 1985 (8)HICOREX 90B SmCo5 500MeV protons 3.02 -13.50HICOREX 96B (SmPr) Co5 1.53 -6.50CRUCORE 18 SmCo5 5.81 -1.64 8.4 16.0CRUCORE 26 Sm2Co17 5.94 -0.30 9.6 10.0NeIGT 27 Nd-Fe-B 0.003 -55.40 17.0

LANL 1986 (9)CRUMAX 282 Nd-Fe-B Gamma 48.8Mrad -0.00 10.8 28.2NeIGT 27 Nd-Fe-B 48.8 Mrad -0.00

Max fluencex 108 n/cm2

LANL 1982 (10)HICOREX 90B SmCo5 800 Mev protons

to produce neutrons1.10 -1.88

HICOREX 96B (SmPr) Co5 1.20 -2.21

LANL 1986 Omegawest reactor (9)CRUMAX Nd-Fe-B Reactor neutrons 2.50 -79.10 10.8 28.2NeIGT 27H Nd-Fe-B 2.50 -86.80 17.0HICOREX 94B Nd2Fe14B 3.80 -14.00INCOR 18 Sm2Co17 2.60 -0.00INCOR 22HE Sm2Co17 2.60 -0.20

James T Volk June 2002 22

fRadiation Damage in SM Cobalt

Demagnetization of RECfrom F. Coninckx et. al.

-120

-100

-80

-60

-40

-20

0

0 5 10 15

dose *1E9 rads

% c

ha

ng

e

Recoma 20

Vacomax 200

Koermax 160

all Sm Cobalt magnet

James T Volk June 2002 23

f

Radiation-Induced Demagnetization(Japanese experience with 200 MeV protons)

• Material Type has large impactRed: N48 High Br (1.4T)

Low Hc (1.15 MA/m)

Blue: N32Z Lower Br (1.14 T)Higher Hc (2.5

MA/m)

• Material Shape has large impact(All samples are discs 10 mm dia)Circle: thickness = 2 mm (Pc = 0.5)Triangle: thickness = 4 mm (Pc = 1.0)Square: thickness = 7 mm (Pc = 2.0)- Higher Permeance coefficient

increases resistance (x 10)

• SmCo is much more resistant than NdFeB

James T Volk June 2002 24

fRadiation damage tests

Variety of particles p, n, d, , e used

ND-Iron Radiation damage not well determined

Energy is low Kev to Mev range

No consistent dosimetry used

All done on free bricks not magnets!

James T Volk June 2002 25

fRadiation Test Dipole Design

PM Material

PM Material

2 inch gap

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fRadiation Damage Issues

• Identify Radiation fields where PM could be used• Obtain consistent data on magnetic field loss• Determine Magnetic Field loss as a function of

Type of radiationAmount of radiation

Dependence on Hc and other magnet parameters

Dependence on manufacturer

James T Volk June 2002 27

fConclusions

• There is plenty of work to do with permanent magnets

• Improve quads for the LINAC• Investigate other applications• Measure effect of radiation on various magnet

material

• Plenty of real work to do!