Modeling of an Extraction Lens System
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Modeling of an Extraction Lens SystemThesis DefenseBachelor of Applied Science
Karine Le DuEngineering Physics
School of Engineering Science, SFU
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March 2003 Thesis Defence
OverviewDehnel Consulting Ltd.Use of Commercial CyclotronsCyclotron Components Extraction Lens SystemScope of the Study Computer Simulation ModelResultsAcknowledgements
Karine Le Du
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March 2003 Thesis Defence Karine Le Du
Current Expertise: Complete Beamline Design Injection System Design Beamline Simulator SoftwareMy Project… Extraction Lens System DesignFuture Endeavors Ion Implantation
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March 2003 Thesis Defence
Use of Commercial Cyclotrons
Photo Courtesy of Ebco Technologies Inc.
Radioisotopes for medical use Detection of soft tissue damage On-site at hospitals
Short half-lives of radioisotopes Bombard target with protons
Necessitates beam of H¯(hydride ions)
Karine Le Du
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March 2003 Thesis Defence
Cyclotron Components
Karine Le Du
Ion Source
Extraction Lenses
Injection Line
Inflector
Cyclotron
Extraction Probe
Beamline
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March 2003 Thesis Defence
Cyclotron Components
Karine Le Du
Ion Source
Extraction Lenses
Injection Line
Inflector
Cyclotron
Extraction Probe
Beamline
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March 2003 Thesis Defence
Extraction Lens Assembly
Karine Le Du
Assembly drawing courtesy of TRIUMF
vacuum chamber
beamstopion sourc
e
z ~ 405mm
Plasma lens
Extraction lens
Shoulder lens
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March 2003 Thesis Defence
Scope of the StudyPurpose Identify how changes to system
parameters (dimensions and voltage potentials) affect H¯ beam characteristics
Provide data to aid an engineer in optimizing the design of an extraction lens system with regards to beam characteristics
Karine Le Du
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March 2003 Thesis Defence
Beam CharacteristicsNormalized Beam Emittance, εN Describes size of beam in phase space Energy normalized
Beam Current, I Percent of beam transmitted Low and high beam current applications
Beam Brightness, b
Karine Le Du
2N
Ib
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March 2003 Thesis Defence
Phase SpaceFour important coordinates that completely describe an ion’s trajectory are (x, x’, y, y’) (x, y):transverse
position (x’, y’): divergence
from longitudinal axis
z: longitudinalposition
Karine Le Du
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March 2003 Thesis Defence
Beam SizeBeam Size: Area enclosed in beam ellipse
Beam Emittance: Proportional to beam size
Karine Le Du
x
x’
Beam ellipse
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March 2003 Thesis Defence
Optimal Beam Characteristics
Normalized Beam Emittance, εN minimize Small emittance is more efficient
Beam Current, I Depends on application
Beam Brightness, b maximize Achieved by maximizing beam current or
minimizing normalized beam emittance
Karine Le Du
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March 2003 Thesis Defence
Computer Simulation Model
SIMION 3D, Version 7.0, INEEL*Model consists of 3 electrostatic lenses
*Idaho National Engineering and Environmental Laboratory
Karine Le Du
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March 2003 Thesis Defence
Assumptions MadeASSUMPTIONS No plasma
meniscus
JUSTIFICATIONS Beyond the scope
of this study
Karine Le Du
No filter magnet
Ignored space charge repulsion and image forces
e¯ stripped out early
Beyond the scope of this study
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March 2003 Thesis Defence
System ParametersE1: Plasma ElectrodeE2: Extraction ElectrodeE3: Shoulder Electrode
V1: Voltage Potential of E1V2: “ “ of E2V3: “ “ of E3
A1: Aperture of E1A2: “ “ E2A3: “ “ E3
D12: Spacing between E1/E2D23: “ “ E2/E3
Karine Le Du
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March 2003 Thesis Defence
Table of Parameter ValuesList of design parameters by name
ID tags & nominal values
Variable parameter test values
Plasma Electrode E1 Voltage potential V1 = -25 kV Aperture diameter
A1 = 13 mm
Extraction Electrode E2 Voltage potential V2 = -22 kV -23 kV -22.5
kV-21.5 kV
Aperture diameter
A2 = 9.5 mm 10.5mm
11.5mm
12.5mm
Shoulder Electrode E3 Voltage potential V3 = 0 V Aperture diameter
A3 = 10 mm 9 mm 11 mm
Separation between electrodes
E1 & E2 D12 = 4 mm 7 mm 10 mm E2 & E3 D23 = 12 mm 8 mm 16 mm Karine Le
Du
List of design parameters by name
ID tags & nominal values
Variable parameter test values
Plasma Electrode E1 Voltage potential V1 = -25 kV Aperture diameter
A1 = 13 mm
Extraction Electrode E2 Voltage potential V2 = -22 kV -23 kV -22.5
kV-21.5 kV
Aperture diameter
A2 = 9.5 mm 10.5mm
11.5mm
12.5mm
Shoulder Electrode E3 Voltage potential V3 = 0 V Aperture diameter
A3 = 10 mm 9 mm 11 mm
Separation between electrodes
E1 & E2 D12 = 4 mm 7 mm 10 mm E2 & E3 D23 = 12 mm 8 mm 16 mm
List of design parameters by name
ID tags & nominal values
Variable parameter test values
Plasma Electrode E1 Voltage potential V1 = -25 kV Aperture diameter
A1 = 13 mm
Extraction Electrode E2 Voltage potential V2 = -22 kV -23 kV -22.5
kV-21.5 kV
Aperture diameter
A2 = 9.5 mm 10.5mm
11.5mm
12.5mm
Shoulder Electrode E3 Voltage potential V3 = 0 V Aperture diameter
A3 = 10 mm 9 mm 11 mm
Separation between electrodes
E1 & E2 D12 = 4 mm 7 mm 10 mm E2 & E3 D23 = 12 mm 8 mm 16 mm
List of design parameters by name
ID tags & nominal values
Variable parameter test values
Plasma Electrode E1 Voltage potential V1 = -25 kV Aperture diameter
A1 = 13 mm
Extraction Electrode E2 Voltage potential V2 = -22 kV -23 kV -22.5
kV-21.5 kV
Aperture diameter
A2 = 9.5 mm 10.5mm
11.5mm
12.5mm
Shoulder Electrode E3 Voltage potential V3 = 0 V Aperture diameter
A3 = 10 mm 9 mm 11 mm
Separation between electrodes
E1 & E2 D12 = 4 mm 7 mm 10 mm E2 & E3 D23 = 12 mm 8 mm 16 mm
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March 2003 Thesis Defence
General Trends
0
0.5
1
1.5
2
2.5
0.5 0.75 1 1.25 1.5 1.75 2normalized beam emittance (mm.mrad)
beam
brig
htne
ss (m
m.m
rad)
-2
D12 = 4 mm
D12 = 7 mm
D12 = 10 mm
less than 39.9% trans.
40% to 49.9% trans.
50% to 59.9% trans.
60% to 69.9% trans.
70% to 79.9% trans.
80% to 89.9% trans.
90% to 99.9% trans.
100% transmission
V2 = -23 kV
V2 = -22.5 kV
V2 = -22 kV
V2 = -21.5 kV
Karine Le Du
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March 2003 Thesis Defence
General Trends
Karine Le Du
1
1.25
1.5
1.75
2
2.25
2.5
0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9
normalized beam emittance (mm.mrad)
beam
brig
htne
ss (m
m.m
rad)
-2
D12 = 10mm 50% to 59.98% trans. 60% to 69.98% trans. 70% to 79.98% trans.
80% to 89.98% trans. 90% to 99.98% trans. 100% transmission V2 = -23 kV
V2 = -22.5 kV V2 = -22 kV V2 = -21.5 kV
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March 2003 Thesis Defence
Ion Trajectories
Karine Le Du
Nominal Configuration,b = 0.341, N =1.136, I = 44%
Highest Beam Brightness,b = 2.351, N =0.508, I = 60.7%
Lowest Beam Brightness,b = 0.127, N =1.916, I = 46.6%
100% Beam Transmission,b = 1.731, N =0.76, I = 100%
b in [(mm·mrad)-2]
N in [mm·mrad]
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March 2003 Thesis Defence
Limitations/Future WorkTest results limited to ranges of parameter values tested
Test wider ranges of valuesBeam loss occurred at downstream aperture of E2
Downstream aperture had fixed size May be cause of apparent ineffectiveness in changing A2
and A3 parameter values?Implement space charge repulsionVary plasma meniscus curvatureImplement magnetic filter
Karine Le Du
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March 2003 Thesis Defence
AcknowledgementsDr. Morgan Dehnel Excellent mentoring and guidance
Dr. John F. Cochran andMr. Steve Whitmore Invaluable feedback
My family Support and encouragement
The Caskey Family, and friends Support and encouragement
Karine Le Du
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March 2003 Thesis Defence
Crude Beam Current Adjustment
Parameter
Suggested value
D12 10 mmD23 16 mmA2 9.5 mm (same)A3 10 mm (same)V2 Vary to achieve desired beam
current make more positive for higher beam current
Karine Le Du
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March 2003 Thesis Defence
Beam Optics
Karine Le Du
z
x
X’
X’
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March 2003 Thesis Defence
Beam Size Beam Emittance: Ellipse Area:
Karine Le Du
nterceptiaximumm xx 'A
N Normalized Emittance: