[PPT] - Modeling of an Extraction Lens System Thesis Defense Bachelor of PowerPoint Presentation

SLIDE 1

Modeling of an Extraction Lens System

Thesis Defense

Bachelor of Applied Science

Karine Le Du

Engineering Physics School of Engineering Science, SFU

SLIDE 2

March 2003 Thesis 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

SLIDE 3

March 2003 Thesis 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

SLIDE 4

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

SLIDE 5

March 2003 Thesis Defence

Cyclotron Components

Karine Le Du

Ion Source Extraction Lenses Injection Line Inflector Cyclotron Extraction Probe Beamline

SLIDE 6

March 2003 Thesis Defence

Cyclotron Components

Karine Le Du

Ion Source Extraction Lenses Injection Line Inflector Cyclotron Extraction Probe Beamline

SLIDE 7

March 2003 Thesis 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

SLIDE 8

March 2003 Thesis 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

ptimizing the design of an extraction lens

system with regards to beam characteristics

Karine Le Du

SLIDE 9

March 2003 Thesis Defence

Beam Characteristics

Normalized 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

 

2 N

I b  

SLIDE 10

March 2003 Thesis 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

SLIDE 11

March 2003 Thesis Defence

Beam Size

Beam Size:

 Area enclosed in beam ellipse

Beam Emittance:

 Proportional to beam size Karine Le Du

x x’

Beam ellipse

SLIDE 12

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

SLIDE 13

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

SLIDE 14

March 2003 Thesis 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

SLIDE 15

March 2003 Thesis 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

SLIDE 16

March 2003 Thesis Defence

Table of Parameter Values

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

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

SLIDE 17

March 2003 Thesis Defence

General Trends

0.5 1 1.5 2 2.5 0.5 0.75 1 1.25 1.5 1.75 2 normalized beam emittance (mm.mrad) beam brightness (mm.mrad)

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

SLIDE 18

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 brightness (mm.mrad)

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

SLIDE 19

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]

SLIDE 20

March 2003 Thesis 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

SLIDE 21

March 2003 Thesis 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

SLIDE 22

March 2003 Thesis Defence

Crude Beam Current Adjustment

Parameter Suggested value

D12 10 mm D23 16 mm A2 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

SLIDE 23

March 2003 Thesis Defence

Beam Optics

Karine Le Du

z x

X’ X’

SLIDE 24

March 2003 Thesis Defence

Beam Size

 Beam Emittance:  Ellipse Area: Karine Le Du

ntercept i aximum m

x x '       A

    

N

 Normalized Emittance: