ferrite tests for mu2e beam-line extinction uses
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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.
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