RF Modeling efforts

blockmindlessUrban and Civil

Nov 16, 2013 (3 years and 11 months ago)

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RF Modeling efforts
on Ion Source at
SNS

Sung
-
Woo Lee

2

Managed by UT
-
Battelle


for the U.S. Department of Energy

Presentation_name

Outlines


External antenna Ion Source development at SNS


Electromagnetic analysis


Identifying the RF hotspots

(E
-
H fields, Surface Current Distribution)


RF power dissipation estimation on each parts


Input impedance estimation for input power matching


Modeling Challenges


Methods of analysis


Model Compatibility


On going EM modeling effort

3

Managed by UT
-
Battelle


for the U.S. Department of Energy

Presentation_name

EM (Electromagnetic) Model on SNS
External Antenna Ion Source


CST MWS model

Antenna

Lumped

Input Port

Plasma model

(Lossy Metal)

Antenna

(Helical Coil)

Magnet Holder

(Copper)

Housing

(Stainless Steel)

4

Managed by UT
-
Battelle


for the U.S. Department of Energy

Presentation_name

External Antenna Ion Source


Power dissipation due to the RF
input power needed to be estimated
for complete thermal analysis on the
sensitive part such as magnet
holder.

Antenna Separator

(Teflon)

Ferrite Ring

(
m
r
: 250)

Teflon/Ferrite/Teflon+Ferrite Cylinder

(m
Ferrite
:250

e
teflon
:2.08)

Magnet Holder

(Copper)

Antenna

(Cu)

Magnet

Holder (Cu)

Plasma

Chamber

5

Managed by UT
-
Battelle


for the U.S. Department of Energy

Presentation_name

E
-
H Field distribution

E
-
field

Case#2

Case#3

Case#4

H
-
field

6

Managed by UT
-
Battelle


for the U.S. Department of Energy

Presentation_name

Surface Current Distribution


Surface Current on the parts can be used for RF power
loss estimation

Case#2

Case#3

Case#4

7

Managed by UT
-
Battelle


for the U.S. Department of Energy

Presentation_name

Power Dissipation Ratio on parts (%)


Power losses calculated for each cases

2MHz

Case #1

Case #2

Case #3

Case #4

Teflon Cylinder
w/o ferrite ring

Teflon Cylinder
w/ ferrite ring

Ferrite Cylinder
w/ ferrite ring

Fer./Tef. Cylinder
w/ ferrite ring

Plasma

Plasma

Plasma

Plasma

Antenna

39.6

2.9

38.7

2.2

53.4

1.2

38.6

2.2

Housing

44.2

3.2

57.8

3.2

23.5

0.5

57.9

3.2

Magnet Holder

15.1

1.1

2.0

0.1

5.4

0.1

2.1

0.1

Plasma

92.7

94.5

97.8

94.5

Total Surface

100.0

100.0

99.5

100

83.1

99.6

99.5

100

Total Volume

0.0

0.0

0.5

0.0

16.9

0.4

0.5

0.0

Plasma

no Plasma

(m
Fer
:250

e
瑥f
:2.08)

Teflon Cylinder

Ferrite Cylinder

Fer/Tef Cylinder

Ferrite Ring

8

Managed by UT
-
Battelle


for the U.S. Department of Energy

Presentation_name

Input Matching Performance

Ferrite Cylinder

Case #3

Teflon Cylinder

Case #2

Fer/Tef Cylinder

Case #4

No Ferrite Ring

Case #1

2MHz

13MHz

w/o Plasma

w/ Plasma

9

Managed by UT
-
Battelle


for the U.S. Department of Energy

Presentation_name

RF EM modeling Challenges


EM analysis software tool (
CST MWS
, HFSS, etc.)


Analysis methods (
CST MWS
)


Transient solution (time
-
domain):


Hexahedron mesh (rectangular shape), Finite Difference Method (FDTD)


Frequency domain solution:


Tetrahedron mesh (
arbitrary shape
), Finite Element Method (
FEM
)

DATA availability, Accuracy, Simulation Speed & Memory issues


Model Compatibility


Difficulties in drawing in 3
-
D EM modeling tool in some
designs


Importing model created from mechanical CAD tool such as
Solidworks

10

Managed by UT
-
Battelle


for the U.S. Department of Energy

Presentation_name

Surface Power Dissipation on Magnet
Holder


magnet holder power loss calculation based on

F
-
domain solution for total loss…

and t
-
domain solution for ratio between the surfaces…

Case#1 no fer ring

with tef cylinder

Case#2 fer ring

with tef cylinder

Case#3 fer ring

with fer cylinder

Case#4 fer ring

with fer/tef cylinder

Total
Surface
Loss

100%

1.595mW

(1.498mW)

100%

0.216mW

(0.19mW)

100%

0.408mW

(0.325mW)

100%

0.211mW

(0.19mW)

Face1
(toward
antenna)

30%

(30)

0.476mW

(0.453mW)

8.2%

(7.6)

0.018mW

(0.014mW)

13.1%

(13.5)

0.054mW

(0.044mW)

19.7%

(19.6)

0.042mW

(0.037mW)

Face2
(outer
surface)

24%

(23)

0.384mW

(0.347mW)

23%

(22.8)

0.049mW

(0.043mW)

12.8%

(12.8)

0.052mW

(0.042mW)

15.1%

(14.6)

0.032mW

(0.028mW)

Face3
(inner
surface)

26%

(26)

0.418mW

(0.39mW)

22%

(20.1)

0.047mW

(0.038mW)

37.8%

(36.3)

0.154mW

(0.118mW)

42.6%

(39.5)

0.09mW

(0.075mW)

Normalized with 1W input power

Face 1

(Toward ANT)

Face 2

(Outer)

Face 3

(Inner)

11

Managed by UT
-
Battelle


for the U.S. Department of Energy

Presentation_name

On going EM Modeling effort


Complete drawing of external antenna (2MHz) Ion
Source with secondary external antenna(13MHz) for
plasma gun

12

Managed by UT
-
Battelle


for the U.S. Department of Energy

Presentation_name

Summary


EM modeling on SNS External Antenna Ion Source for
RF performance estimation.


RF E
-
H fields, Surface Currents, power losses are
calculated.


Antenna input impedance for matching network design.


RF EM modeling issues in terms of simulation (speed,
accuracy and data availability) and model compatibility
are addressed.


Complete modeling for more close to real design is
being developed.