Post on 19-Jan-2016
description
H- Ion Source Development
Dan Faircloth
ISIS Operational Ion SourcePenning H- ion sourceSurface Plasma Source (SPS) 35 mA through 0.610 mm aperture200-250 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
Mica
Mounting Flange
Copper Spacer
Ceramic
H- Ion Beam Extract Electrode
Cathode
Anode
Penning Pole Pieces Discharge Region
10mm
Aperture Plate
Source Body
53.7mm
35kV
17kV
Platform Ground
Platform DC Power Supply
Pulsed Extract Power
Supply
Post Extraction
Acceleration Gap
Laboratory Ground
Extraction Electrode,
Coldbox and Analysing Magnet all
Pulsed
35keV H- Beam
+-
+-
18kV
Development Goals
• Increase Pulse Length
• Increase Output Current
• Reduce Emittance
• Maximise Lifetime
35mA to 70mA
200µs to 1.5ms
Thermal Modelling3D Finite Element Model of the Ion Source using ALGOR.
600520440360280200
Steady State Solution
450
500
550
600
650
700
0 0.005 0.01 0.015 0.02 0.025 0.03
Time (seconds)
Te
mp
era
ture
(C
)
012345
0 0.005 0.01 0.015 0.02 0.025 0.03Ins
tan
tan
eo
us
Po
we
r
(kW
) 1000μs duty
Cathode Surface
Anode Surface
ΔT= 73 ºC
ΔT= 39 ºC
Transient Solution
Computational Fluid Dynamic Cooling Calculation
Maximum Discharge Length Obtained1.8ms @ 50Hz
-80
-60
-40
-20
0
20
40
60
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Time (us)
Discharge Current (A)
Beam Current (mA)
Extract Volts (kV)
17 keV normalisedHrms= 0.04 mm mradVrms= 0.16 mm mrad
Existing Extract
17 keV normalisedHrms= 0.03 mm mradVrms= 0.03 mm mrad
Terminated Pierce Extract
Electromagnetic Modelling3D Finite Element Model of the Ion Source using MAFIA.
Potential in Extract Region
0T 0.5T
Magnetic Field in Coldbox
Correctly Terminated Analysing Field
ISDR Infrastructure Changes
Ion SourceAssembly
MagnetAssembly
Top Loading Ion Source
Penning Field
B
Pole tip extensions on the 90°
Analysing Magnet
Separate Penning Field
Ion SourceAssembly
MagnetAssembly
Top Loading Ion Source Separate Penning Field
Penning Field
B
ISDR Infrastructure Changes
Collaboration with IHEP, CAS
Dr. Ouyang and Prof. Zhang
Feb 2007: Dr. He Wei testing ion source components manufactured in China.
78 mA 500 µs 50 Hz
-100
-80
-60
-40
-20
0
20
40
60
80
100
120
-100 0 100 200 300 400 500 600 700 800 900 1000
Ext V (kV)
Dis Cur (A)
H- (mA)
Development Goals
• Increase Pulse Length
• Increase Output Current
• Reduce Emittance
• Maximise Lifetime
35mA to 70mA
200µs to 1.5ms
Improved Diagnostics
Retarding Potential Energy Analyzer
Work done in collaboration with Oxford University
0
0.2
0.4
0.6
0.8
1
1.2
-70.00 -20.00 30.00 80.00
Tra
nsm
issi
on
(%)
Bias Voltage (V)
-0.03
-0.02
-0.01
0
0.01
-70.00 -20.00 30.00 80.00
δ(T
rans
mis
sion
) /
δ(−
Vb)
(
%/V
)
Bias Voltage (V)
σ = 17.6 eV +/- 1.5 eV
0
0.2
0.4
0.6
0.8
1
1.2
-70.00 -20.00 30.00 80.00
40A
50A
60A
70A
80A
90A
95A
Bias Voltage (V)
Discharge Current (A)
Tra
nsm
issi
on
(%)
10
15
20
25
30
35
30 50 70 90 110
Discharge Current (A)
Spe
ctru
m w
idth
σ (
eV)
Faraday Cup
IPotential Hill
H- Beam
Current Work
17 kV Extract Potential
-60 -600-30 30
0
50
100
-50
-100
x (mm)
x ‘(m
Ra
ds)
-60 -600-30 30
0
50
100
-50
-100 y (mm)
y ‘(mRads)
0.84 norm πmm mRad 0.92 norm πmm mRad
62 mA Beam Current
10 kV Extract Potential
-60 -600-30 30
0
50
100
-50
-100 x (mm)
x ‘(mRads)
-60 -600-30 30
0
50
100
-50
-100 y (mm)
y ‘(mRads)
0.48 norm πmm mRad 0.55 norm πmm mRad
32 mA Beam Current
6.5 kV Extract Potential
-60 -600-30 30
0
50
100
-50
-100 y (mm)
y ‘(mRads)
-60 -600-30 30
0
50
100
-50
-100 x (mm)
x ‘(mRads)
0.16 norm πmm mRad 0.32 norm πmm mRad
13 mA Beam Current
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
Ion Source Development Rig
Pepper Pot Emittance Measurement
Support rods
CameraMoving rod
Window
Mounting flange
• 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
Scintillator and Pepperpot
Details in the next talk
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
Questions?