1G. Velev

1/24/ 2011

Ferrite Tests for Mu2e Beam-Line Extinction Uses

G. VelevTechnical Division

Magnet Systems Department

2G. Velev

1/24/ 2011

Introduction

• Ferrite pulsed magnets are commonly used in the accelerator applications – kickers – injection, extraction, gap clearing (recently MI)– Orbump – beam orbit manipulation

• All of them have a low operational duty cycle, practically <1-3%• For Mu2e, an experiment which searches for a μ-e conversion with

an unprecedented sensitivity of ~ 10-16 a new type AC dipoles are needed

• These dipoles will be used to extinguish the protons at the level of 10-6 -10-7 between the bunches. They should work continuously at 300 kHz ( Bmax = 160 G) and possibly at 5.1 MHz (Bmax ~ 10 G) at 100% duty cycle

• In 2009, we started a R&D to select suitable ferrites for these dipoles

• Collaboration with Japan, COMET experiment needs similar technology.

3G. Velev

1/24/ 2011

Time

Dip

ole

Fie

ld

~100 ns ~100 ns1.7ms

Beam cleaning

• The idea is to synchronize the beam bunches and AC magnetic field

• 100 ns bunches separated with 1.7 μs gap ~ 600 kHz

• The bunches are moving on the nodes - 300 kHz

• More information – Eric Prebys note: http://mu2e-docdb.fnal.gov/cgi-bin/RetrieveFile?docid=709

Collimator

Out of time beam

In time beam

dipole

4G. Velev

1/24/ 2011

Beam cleaning: current version

Time

Dip

ole

Fie

ld (

G)

Collimator

Out of time beam

In time beam

dipoles

300 kHz

5.1 MHz

5G. Velev

1/24/ 2011

B-H curve • B = mH, in ferrites m =m(H,T(C), …)• The losses in ferrite core

~ area under the B-H curve

• At low frequency - hysteresis loss

• At high frequency - eddy current loss

B

rBSfreqCP

freqP

PPP

eddy

hysteresis

eddyhysteresistotal

/

~

...

2max

2

H

Ptotal0

2000

4000

6000

8000

10000

12000

14000

-100 -50 0 50 100 150 200

Temp (C)

Perm

eabi

lity

rel perm

6G. Velev

1/24/ 2011

Ferrite samples

• Ferrite types: MnZn, NiZn

• Frequency: 300kHz, 5.1MHz

Ferrites Geometry

ferrite

10 m

m

«1 plate» geometry

ferrite

ferrite 10 m

misolator

«2 plate» geometry

Eddy Currents

Eddy CurrentsMaterial Properties

· MnZn NiZn

Rel.Permeabillity@ 25 C

6500 625

Resistivity (-m)

102 106

Thermal Conductivity

(W/K/m)4.5 4.3

Sample plate

10 RTDs

200x200x10 mm3

200x200x5 mm3

7G. Velev

1/24/ 2011

PowerAmp

Shunt

ADC DAC

FerritePlate

FaradayCage

Temp.Read -

out

RTD

1

2

RC

PXI PXIPXI

Pick-upCoil

InductionCoil

Integrator

PXI InterfaceBox

X10

Oscilloscope

Test system

8G. Velev

1/24/ 2011

ANSYS simulation Magnetic flux density @ direction Temperature Distribution

9G. Velev

1/24/ 2011

B-H curves - MnZn

10G. Velev

1/24/ 2011

Heating comparison:1 plate vs 2 plates MnZn

Low eddy currents

High eddy currents

11G. Velev

1/24/ 2011

MnZn@300 kHz

MnZn , 300 kHz, 1 plate

0.5 60 58 60 22.7

1.2 168 154 166 31.6

1.8 243 230 196 42.6

3.0 356 341 201 65.0

4.1 401 297 207 78.4

Current A-turns

Bmax (G)

Bbegin (G)

Bend

(G)

T max

(C)

MnZn, 300kHz, 2 plates

0.7 60 60 54 22.3

1.4 171 164 154 31.2

2.0 268 256 202 36.5

2.7 342 296 231 40.9

12G. Velev

1/24/ 2011

MnZn@5.1MHz

MnZn , 5.1 MHz, 2 plates

3.2 5.8 4.2 5.3 23.3

7.2 10.4 9.2 9.8 32.9

10.6 15.0 13.5 14.0 46.9

17.9 21.1 20.6 18.7 77.4

Current A-turns

Bmax (G)

Bbegin (G)

Bend

(G)

T max

(C)Current A-turns

Bmax (G)

Bbegin (G)

Bend

(G)

T max

(C)

13G. Velev

1/24/ 2011

B-H curve - NiZn

14G. Velev

1/24/ 2011

NiZn , 5.1 MHz, 1 plate

3.3 6.0 4.9 5.5 21.7

9.6 9.9 8.5 9.4 28.0

12.3 11.7 10.6 11.2 37.2

13.7 12.3 11.4 10.7 42.4

25.1 18.9 18.7 12.4 65.2

NiZn@5.1MHzCurrent A-turns

Bmax (G)

Bbegin (G)

Bend

(G)

T max

(C)

NiZn , 300 kHz, 1 plate

3.6 64 61 64 23.5

5.7 102 101 95 28.3

7.8 146 143 111 40.1

9.3 167 160 116 73.2

15G. Velev

1/24/ 2011

Ferrite selection

• Both materials satisfy the criteria for magnet strength

• Due to the low resistivity and large eddy current effect, the thickness of MnZn ferrite plates should be ~ 5 mm.

• At such high frequencies and power, for MnZn plate we need good insulator between ferrites and power bus - problem with insulation due to corona discharge

16G. Velev

1/24/ 2011

Magnet design - x-section

• Two designs were considered – magnet with C and H shape of the ferrite plates.

IEEE Applied Superconductivity, v. 20,

p. 1642.

17G. Velev

1/24/ 2011

Current Model Design

Beam direction

NiZn Ferrite plates

18G. Velev

1/24/ 2011

Summary

• We measured MnZn and NiZn ferrite samples at 300 kHz and 5.1 MHz. Both materials will satisfy the AC dipole requirements.

• Building a magnet prototype based on the selected NiZn ferrites – simple design due to the high resistivity of the material and no-insulation between the ferrites and copper bus

• This summer – we plan to test the prototype, including 5.1 MHz

• Depending on the result an iteration may be needed. • Contributions: V. Kashikhin, S. Makarov, D. Harding,

E. Prebys and PARTI students: I. Iedemska and E. Bulushev.