1. H- Ion Source Development
Dan Faircloth

2. ISIS Operational Ion Source
Penning H- ion source
Surface Plasma Source (SPS)
35 mA through 0.610 mm aperture
s, 50 Hz  1% duty cycle
 20 ml/min H2
 3 g/month Cs
0.17  mm mrad
(665 keV, 35 mA, rms)
20-30 day average lifetime

3. H- Ion Beam
Extract Electrode
Aperture Plate
Penning Pole Pieces
Discharge Region
Ceramic
Anode
Source Body
Copper Spacer
Cathode
Mica
10mm
Mounting Flange

4. Platform DC Power Supply
Platform Ground
35kV
Pulsed Extract Power Supply
17kV - +
Laboratory Ground
18kV
Extraction Electrode, Coldbox and Analysing Magnet all Pulsed - +
35keV
H- Beam
53.7mm
Post Extraction Acceleration Gap

5. Development Goals Increase Pulse Length Increase Output Current
Reduce Emittance
Maximise Lifetime
200µs to 1.5ms
35mA to 70mA

6. Thermal Modelling Steady State Solution
600
520
440
360
280
200
Steady State Solution
3D Finite Element Model of the Ion Source using ALGOR.
Computational Fluid Dynamic Cooling Calculation
1000μs duty
Cathode Surface
Anode Surface
ΔT= 73 ºC
ΔT= 39 ºC
Transient Solution

7. Maximum Discharge Length Obtained 1.8ms @ 50Hz

8. Electromagnetic Modelling
17 keV normalised
Hrms= 0.03  mm mrad
Vrms= 0.03  mm mrad
Terminated Pierce Extract
3D Finite Element Model of the Ion Source using MAFIA.
17 keV normalised
Hrms= 0.04  mm mrad
Vrms= 0.16  mm mrad
Existing Extract
Potential in Extract Region
0T 0.5T
Magnetic Field in Coldbox
Correctly Terminated Analysing Field

9. ISDR Infrastructure Changes
Top Loading Ion Source
Separate Penning Field
Ion Source
Assembly
Magnet
Pole tip extensions on the 90° Analysing Magnet
Penning Field B

10. ISDR Infrastructure Changes
Top Loading Ion Source
Separate Penning Field
Ion Source
Assembly
Penning Field B
Magnet
Assembly

11. Collaboration with IHEP, CAS
Dr. Ouyang and Prof. Zhang
Feb 2007: Dr. He Wei testing ion source components manufactured in China.

12. 78 mA 500 µs 50 Hz

13. Development Goals Increase Pulse Length Increase Output Current
200µs to 1.5ms
Increase Pulse Length
Increase Output Current
Reduce Emittance
Maximise Lifetime
35mA to 70mA

14. Improved Diagnostics

15. Retarding Potential Energy Analyzer
Transmission (%)
Bias Voltage (V)
δ(Transmission) / δ(−Vb) (%/V)
Bias Voltage (V)
σ = 17.6 eV +/- 1.5 eV
Bias Voltage (V)
Discharge Current (A)
Transmission (%)
Spectrum width σ (eV)
Faraday Cup I
H- Beam
Potential Hill
Work done in collaboration with Oxford University

16. Current Work

17. 17 kV Extract Potential 62 mA Beam Current 0.84 norm πmm mRad
-60
-30 30 50
100
-50
-100
x (mm)
x ‘(mRads)
100 50
y ‘(mRads)
-50
-100
-60
-30 30
-60
y (mm)
0.84 norm πmm mRad
0.92 norm πmm mRad

18. 10 kV Extract Potential 32 mA Beam Current 0.48 norm πmm mRad
100
100 50 50
x ‘(mRads)
y ‘(mRads)
-50
-50
-100
-100
-60
-30 30
-60
-60
-30 30
-60
x (mm)
y (mm)
0.48 norm πmm mRad
0.55 norm πmm mRad

19. 6.5 kV Extract Potential 13 mA Beam Current 0.16 norm πmm mRad
100
100 50 50
x ‘(mRads)
y ‘(mRads)
-50
-50
-100
-100
-60
-30 30
-60
-60
-30 30
-60
x (mm)
y (mm)
0.16 norm πmm mRad
0.32 norm πmm mRad

20. Scintillator Measurements
5 kV Ext
5.5 kV Ext
6 kV Ext
6.5 kV Ext
7 kV Ext
8 kV Ext
9 kV Ext
11 kV Ext

21. Ion Source Development Rig

22. Pepper Pot Emittance Measurement
To help understand why the emittance is so large
To allow optimised design of the LEBT for the Front End Test Stand
To develop diagnostic experience for the FETS collaboration
Mounting flange
Details in the next talk
Window
Support rods
Moving rod
Scintillator and Pepperpot
Camera

23. Future Work Scanning Pepperpot and Scintillator studies
Space charge studies with Krypton
Different extraction geometries
Different post acceleration gap
Plasma meniscus modelling
More detailed beam transport modelling
Different materials for extended lifetime studies

24. Questions?