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Modeling of an Extraction Lens System Thesis Defense Bachelor of Applied Science Karine Le Du Engineering Physics School of Engineering Science, SFU.

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Presentation on theme: "Modeling of an Extraction Lens System Thesis Defense Bachelor of Applied Science Karine Le Du Engineering Physics School of Engineering Science, SFU."— Presentation transcript:

1 Modeling of an Extraction Lens System Thesis Defense Bachelor of Applied Science Karine Le Du Engineering Physics School of Engineering Science, SFU

2 March 2003Thesis Defence Overview Dehnel Consulting Ltd. Use of Commercial Cyclotrons Cyclotron Components Extraction Lens System Scope of the Study Computer Simulation Model Results Acknowledgements Karine Le Du

3 March 2003Thesis Defence Karine Le Du Current Expertise: Complete Beamline Design Injection System Design Beamline Simulator Software My Project… Extraction Lens System Design Future Endeavors Ion Implantation

4 March 2003Thesis 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

5 March 2003Thesis Defence Cyclotron Components Karine Le Du Ion Source Extraction Lenses Injection Line Inflector Cyclotron Extraction Probe Beamline

6 March 2003Thesis Defence Cyclotron Components Karine Le Du Ion Source Extraction Lenses Injection Line Inflector Cyclotron Extraction Probe Beamline

7 March 2003Thesis Defence Extraction Lens Assembly Karine Le Du Assembly drawing courtesy of TRIUMF vacuum chamber beamstop ion source z ~ 405mm Plasma lens Extraction lens Shoulder lens

8 March 2003Thesis Defence Scope of the Study Purpose 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

9 March 2003Thesis Defence Beam Characteristics Normalized Beam Emittance, ε N 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

10 March 2003Thesis Defence Phase Space Four 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: longitudinal position Karine Le Du

11 March 2003Thesis Defence Beam Size Beam Size: Area enclosed in beam ellipse Beam Emittance: Proportional to beam size Karine Le Du x x’ Beam ellipse

12 March 2003Thesis Defence Optimal Beam Characteristics Normalized Beam Emittance, ε N  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

13 March 2003Thesis 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

14 March 2003Thesis Defence Assumptions Made ASSUMPTIONS 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

15 March 2003Thesis Defence System Parameters E1: Plasma Electrode E2: Extraction Electrode E3: Shoulder Electrode V1: Voltage Potential of E1 V2: “ “ of E2 V3: “ “ of E3 A1: Aperture of E1 A2: “ “ E2 A3: “ “ E3 D12: Spacing between E1/E2 D23: “ “ E2/E3 Karine Le Du

16 March 2003Thesis Defence Table of Parameter Values List of design parameters by name ID tags & nominal values Variable parameter test values Plasma ElectrodeE1 Voltage potentialV1 = -25 kV Aperture diameterA1 = 13 mm Extraction ElectrodeE2 Voltage potentialV2 = -22 kV-23 kV-22.5 kV-21.5 kV Aperture diameterA2 = 9.5 mm10.5mm11.5mm12.5mm Shoulder ElectrodeE3 Voltage potentialV3 = 0 V Aperture diameterA3 = 10 mm9 mm11 mm Separation between electrodes E1 & E2D12 = 4 mm7 mm10 mm E2 & E3D23 = 12 mm8 mm16 mm Karine Le Du List of design parameters by name ID tags & nominal values Variable parameter test values Plasma ElectrodeE1 Voltage potentialV1 = -25 kV Aperture diameterA1 = 13 mm Extraction ElectrodeE2 Voltage potentialV2 = -22 kV-23 kV-22.5 kV-21.5 kV Aperture diameterA2 = 9.5 mm10.5mm11.5mm12.5mm Shoulder ElectrodeE3 Voltage potentialV3 = 0 V Aperture diameterA3 = 10 mm9 mm11 mm Separation between electrodes E1 & E2D12 = 4 mm7 mm10 mm E2 & E3D23 = 12 mm8 mm16 mm List of design parameters by name ID tags & nominal values Variable parameter test values Plasma ElectrodeE1 Voltage potentialV1 = -25 kV Aperture diameterA1 = 13 mm Extraction ElectrodeE2 Voltage potentialV2 = -22 kV-23 kV-22.5 kV-21.5 kV Aperture diameterA2 = 9.5 mm10.5mm11.5mm12.5mm Shoulder ElectrodeE3 Voltage potentialV3 = 0 V Aperture diameterA3 = 10 mm9 mm11 mm Separation between electrodes E1 & E2D12 = 4 mm7 mm10 mm E2 & E3D23 = 12 mm8 mm16 mm List of design parameters by name ID tags & nominal values Variable parameter test values Plasma ElectrodeE1 Voltage potentialV1 = -25 kV Aperture diameterA1 = 13 mm Extraction ElectrodeE2 Voltage potentialV2 = -22 kV-23 kV-22.5 kV-21.5 kV Aperture diameterA2 = 9.5 mm10.5mm11.5mm12.5mm Shoulder ElectrodeE3 Voltage potentialV3 = 0 V Aperture diameterA3 = 10 mm9 mm11 mm Separation between electrodes E1 & E2D12 = 4 mm7 mm10 mm E2 & E3D23 = 12 mm8 mm16 mm

17 March 2003Thesis Defence General Trends Karine Le Du

18 March 2003Thesis Defence General Trends Karine Le Du

19 March 2003Thesis 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]

20 March 2003Thesis Defence Limitations/Future Work Test results limited to ranges of parameter values tested Test wider ranges of values Beam 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 repulsion Vary plasma meniscus curvature Implement magnetic filter Karine Le Du

21 March 2003Thesis Defence Acknowledgements Dr. Morgan Dehnel Excellent mentoring and guidance Dr. John F. Cochran and Mr. Steve Whitmore Invaluable feedback My family Support and encouragement The Caskey Family, and friends Support and encouragement Karine Le Du

22 March 2003Thesis Defence Crude Beam Current Adjustment ParameterSuggested value D1210 mm D2316 mm A29.5 mm (same) A310 mm (same) V2 Vary to achieve desired beam current  make more positive for higher beam current Karine Le Du

23 March 2003Thesis Defence Beam Optics Karine Le Du z x X’

24 March 2003Thesis Defence Beam Size Beam Emittance: Ellipse Area: Karine Le Du Normalized Emittance:


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