NLC - The Next Linear Collider Project Oct 01 MAC James T Volk October 2001 MAC meeting Magnet Systems for the NLC James T Volk October 26, 2001

NLC - The Next Linear Collider Project

Oct 01 MAC James T Volk

October 2001 MAC meeting

Magnet Systems for the NLCJames T Volk

October 26, 2001


Permanent Magnet Team

• J DiMarco, A Drozhdin, D Finley, V Kashikhin, N Solyak V Tsvetkov, J Volk

Fermilab

• J Alonso, Jing-Young Jung, (K Robinson). R Schleuter

LBNL

• Cherrill Spencer, Carl Rago

SLAC



Magnet Measurement

• Stretched Wire at Fermilab– X and Y stages

• Stretched wire at SLAC– X stage only

• Rotating Coil at SLAC– Two 50 turn coils able to buck out quad signal and get harmonics

• Tested systems with permanent magnet at constant temperature



Stability of Center Measurements Fermilab

0.5 m



18 hoursOct 01 MAC James T Volk

Stability of Rotating Coil SLAC


Measurement Upgrades

• Fermilab could upgrade stretched wire stages for 120 k$

• This would improve center measurements to better than 0.5 micron

• SLAC is upgrading to both X&Y stages with 0.5 micron accuracy.



Permanent Magnet Types

Wedge Magnet

Corner Tuner


Pole

Pole magnet

Tuning rod

Wedge magnetTuning Rod

Pole magnet

Pole


Corner Tuner Y Center Vs. YGdl

FCS001

-60.00

-50.00

-40.00

-30.00

-20.00

-10.00

0.00

10.00

13 14 15 16 17 18

Intergal Gdl Tesla

Y C

ente

r m

icro

met

ers



Wedge Data

FWSQ003

-25.0

-20.0-15.0

-10.0-5.0

0.0

5.010.0

15.020.0

25.0

-27.0 -26.0 -25.0 -24.0 -23.0 -22.0

Intergal ygdl Tesla

y c

ente

r m

icro

met

ers

1,2,3,4

2,3,4,1

3,4,1,2

4,1,2,3



Permanent Magnet Types

Sliding Shunt

Rotating Quad

Magnets Pole

Sliding Shunt

FixedFixed Rotating



Sliding Shunt Data

FSSQ001

0

10

20

30

40

21 22 23 24 25 26 27

Integal Gradient Tesla

Y c

ente

r m

icro

ns



Counter Rotating Quad

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

Oct 01 MAC James T VolkIntergal Gradient


Electrical Corrector Coils

• By adding electrical corrector coils to any of these magnets center stability can be held to under one micron

• 1 amp can correct center shift by 20 micrometers

• Advantage is small power supply and cables

• No LCW


Prototype Electromagnetic NLC Linac Quadrupole, Under TestPrototype Electromagnetic NLC Linac Quadrupole, Under Test

Synflex Water Hoses

DC Power LeadModified Motor Quick Disconnect

Recessed Core Belt

C1006 Solid Steel Modular Core,

215.9 mm long

Potted Coil, 21 Turns

Thermocouple

Thermal Switch

1/4” Round,Seamless Cu Tubing, Monolithic Coil Lead


Results

Max GradTesla

Min GradTesla

Center ShiftMicrons

Corner 17.5 14.1 60.0

Wedge 1 23.7 18.4 20.0

Wedge 2 26.4 23.0 >20.0

Sliding Shunt 25.9 21.8 15.0

Rotating 36.3 30.3 4.5

Electromagnet 33.2 27.4 1.0



Center Shift Studies

• For the Wedge magnet PANDIRA was used to model the center shift

• One of the four rods was move from the balanced position along and across the field in steps of 0.001 inches

• A change in the field near the center of the quad of 0.7 Gauss equals a 1 micrometer shift in the center

• Shift of the rod along the field has the biggest effect


Shifting a Tuning Rod


Along the Field

Across the Field

Three other rods remain fixed


Center shift due to tuner rod wobble

Field shift tuners forward

-243.0

-242.8

-242.6

-242.4

-242.2

-242.0

-241.8

-241.6

-241.4

-241.2

0.00 2.00 4.00 6.00 8.00

Tuner shift mils

By G

au

ss

along field

across field

1 micron center shift



Emitance Growth

• A Drozhdin and N Solyak at Fermi have been modeling emmitance growth

• Section of LINAC from 10 to 20 GeV

• 32 quads all of same strength

• Start by assuming perfect quad no higher harmonics or skew moments

• Counter rotate single quad

• Then counter rotate pair (Focussing and Defocusing) quad

• Will add random skew quadrupole moment of 1 x 10-4



Horizontal size for quad with no correction



Horizontal size growth with correction



Vertical size no correction



Vertical size with correction



Phase Space Plots

Permanent magnet

Electro magnet

No Correction

Corrected



Beam Size with and without correction



Beam growth

• By rotating a focussing and defocusing quad in opposite directions at the same time the beam growth remains small.



SUMMARY of LBL/SLAC DESIGN WORK on DR MAGNETS

I. Damping Ring Transport Line Dipole : 2 cm gap, B(gap)= 14.43KG, L=0.6m

• Both Ferrite and NdFeB (“Neo”) bricks with iron poles and core were tried..

• End effect and effect of temperature compensating material were both accounted for in the 2-D PANDIRA models.

• Resulting models: Ferrite magnet (86”) is much taller than Neo magnet (16.26”).

• Relaxing field strength by 10 % and increasing effective length by 10 %

=> magnet height smaller:

Ferrite magnet: 28 % height reduction, 26 % PM volume reduction

Neo magnet: 10 % height reduction, 4 % PM volume reduction

• Neo magnet: compact, small dimensions.

If radiation were not a potential problem, Neo magnet would be preferred.

• Gradient Dipole for Main Damping Rings: 4cm gap at center, B(gap)=12KG

• Has to be an electromagnet. Tight field variation requirements. Grad=660.5 G/cm

• By shimming pole tip, the field variation along x direction meets the requirement.

• But not yet found the pole tip shape to meet the tolerance in y direction



III. Main Damping Ring quadrupoles modeled as permanent magnets

• Ferrite and Neo bricks with iron poles and core and rotating rod tuners have been tried.

• End effect and effect of temperature compensating material were both accounted for in the 2-D PANDIRA models.

• Outer iron core is circular: Ferrite quad (R=16.4”) is larger than Neo quad (R=6.1”).

• Tuning rod is used to create +/- 10 % variation in integrated strength.

• Torque for turning the tuning rods is very high in Ferrite quad.

• To estimate loss of B(pole tip) thro’ end effect: 3-D TOSCA model been made.

• From TOSCA calcs: adding steel end plate near magnet does not reduce the end effect.

• Same DR quads been modeled in POISSON as electromagnets

• The magnet radius: 10” for 2 cm pole tip magnet and 9.8” for 3 cm pole tip magnet.

• Temperature rise in the coil: 13.6 oC for 2 cm pole tip and 13.7 oC for 3 cm pole tip

SUMMARY of LBL/SLAC DESIGN WORK on DR MAGNETS



DR Quads Magnet Comparison

Magnet Magnet radius pole tip radiusFerrite magnet 16.4" 2 cm

Neo magnet 6.1" 2 cmElectromagnet 10" 2 cm

Ferrite magnet 15.5" 3 cmNeo magnet 6.5" 3 cm

Electromagnet 9.8" 3 cm



Radiation Damage

• Investigations started about 1980 by several groups

• Many different particles n, p, • Both Sm Cobalt and ND Iron were tested

• All experiments used free bricks

• Wide variety of results everything from no change to reversal of the field direction.

• Roughly Sm Cobalt ok up to 109 rads ND Iron 107 rads

• Higher the coercivity the better

• Table next slide give a summary



Radiation DamageLuna et al. NIM 1989

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 -13.50 8.2 >1.5HICOREX 96B (SmPr) Co5 1.53 -6.50 8.8 1.5CRUCORE 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 8.2 >1.5

HICOREX 96B (SmPr) Co5 1.20 -2.21 8.8 1.5

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



Radiation Damage

• No real consistent data

• Heating a local area can cause domain to flip

• Internal demagnetizing fields can speed this up M/M goes as Volume of grain/ Volume of sample

• Need to know grain size and manufacturing process

• Higher Coercivity the better

• Learn from Undulator experience

• Need to test real magnet with real load line

• Under real exposure conditions



Time Decay Data

• Fermilab has 4+ years experience with Ferrite

• No degradation seen in 8 GeV transferline – 750 meter long

– 45 dipoles, 65 gradient, 9 quadrupoles

• Log(time) decay well measured from RGF005-1

• Expect that Sm Cobalt and Nd Iron will have similar decay

• Need to determine decay constants for both materials



RGF005-1 Data

RGF005-1

-6.00

-4.00

-2.00

0.00

2.00

4.00

6.00

8.00

11/28/1997 03/08/1998 06/16/1998 09/24/1998 01/02/1999 04/12/1999 07/21/1999 10/29/1999 02/06/2000 05/16/2000 08/24/2000

date

brel

uni

ts



Fermilab Recycler Ring

• 5th largest storage ring

• 8 GeV fixed energy antiproton storage

• All ferrite 60,000 bricks ( 25.4 x 101.6 x 152.4 mm)

• 400 gradient magnet 100 quadrupoles

• Magnets built in 1997 and 98



Recycler Tune Numbers

-0.011 0.015Difference

24.40425.444Measured

24.41525.429Design (MAD)

VERT.HORIZ.

Magnets are stable after 3 years



Summary

• In 2 years we have produced 4 styles of permanent magnet quadrupoles

• Both SLAC and Fermi have measurement systems good enough for testing and plans to improve them

• The counter rotating quads meet the requirements

• Two other (wedge and sliding shunt) can meet requirements with some more effort

• Emmittance growth in counter rotating quads is no problem if pairs of quads are rotated simultaneously



Summary

• Possible application of PM in Damping rings

• Radiation damage needs more testing but we believe it can be resolved

• Stability and aging issues need to be tested

• Good indications from the FNAL Recycler that this is not a problem

• There is a good working relationship between the labs

• We continue to make steady progress on these issues

• Able to make realistic cost estimates


Documents

NLC - The Next Linear Collider Project Oct 01 MAC James T Volk October 2001 MAC meeting Magnet Systems for the NLC James T Volk October 26, 2001