A new electron beam ion source as
charge breeder for rare isotope
beams at TRIUMF
Stepan Dobrodey
EMILIE Workshop 2016
The Electron Beam Ion Source
The Electron Beam Ion Source
Requirement: Accept a beam with 100 Hz repetition
rate and provide ions with 10 – 20 % population in
one specific charge state
The Electron Beam Ion Source
Why do we need simulations?
●
●
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Ensure that we can meet the requirements
Very useful tool for diagnostics in near future
Prediction of some parameters for charge breeding
Simulation Steps
1) Create electrostatic and magnetic fields with the finite elements method
extracted from a 3D model of the EBIS
2) Simulate emission of electron beam and propagation into the trap
3) Obtain axial and radial space charge
4) Inject ions (include charge breeding during injection)
5) Extraction (work in progress)
Gun
Collector
Electron
beam
Inject:
Singly
charged
Ions
Simulation Steps
1) Create electrostatic and magnetic fields with the finite elements method
extracted from a 3D model of the EBIS
2) Simulate emission of electron beam and propagation into the trap
3) Obtain axial and radial space charge
4) Inject ions (include charge breeding during injection)
5) Extraction (work in progress)
Gun
Collector
Electron
beam
Extract: Highly
charged ions
Electric and Magnetic Fields
Electrostatic potential
Helmholtz coils
Helmholtz
coils
Transition
Transition
region
region
Drift
Drifttubes
tubes
Electron
gun
Electron gun
Symmetry axis
Collector
Collector
Electric and Magnetic Fields
Electrostatic potential
Helmholtz coils
Transition
region
Drift tubes
Electron gun
Symmetry axis
Collector
Electron Beam
Radius (mm)
50
40
30
20
10
Radius (mm)
0
-200
0
200
600
800
200
600
800
6
4
50 µm
50 µm
2
0
-200
0
Z-Axis (mm)
First Injection Simulations
Ion Injection:
●
Potassium 1+ ions
●
15 keV beam energy
● ε
4RMS = 5 π mm mrad
●
Drift Tubes at 14.7 kV
Sikler Lens
Collector
start
Trap Center
Ions
750[mm]
First Injection Simulations
Ion Injection:
●
Potassium 1+ ions
●
15 keV beam energy
● ϵ
4RMS = 5 π mm mrad
●
Drift Tubes at 14.7 kV
No charge breeding included
during time of flight into the trap
Sikler Lens
Collector
start
Trap Center
Ions
750[mm]
Charge Breeding Simulations
Initial ion: Potassium 1+
Electron beam energy: 15 keV
Electron beam Current: 500 mA
22% 3+
50% 2+
23% 1+
…
1+
2+
3+
...
Ion Injection:
●
Potassium 1+ ions
●
15 keV beam energy
●
150 ions
●
Drift Tubes at 14.7 kV
●
Charge breeding during ToF
Abundance of charge state
Relative abundance
Injection Simulations
1+
Isotopes reach
trap center after
1+
6µs
2+
2+
3+
3+
Time (µs)
Large rectangular
phase space
Injection Simulations
Not accepted
Accepted, 1+
Accepted, 2+
Injection Simulations
Not accepted
Accepted, 1+
Accepted, 2+
Phase space:
57 π mm mrad
Injection Simulations
Not accepted
Accepted, 1+
Accepted, 2+
Required:
4.5 π mm mrad
(90 % of injected ions)
Phase space:
57 π mm mrad
Diagnostics of trap content
Diagnostics of trap content
●
Processes in an EBIS:
–
Ionization
–
Electron impact excitation
–
Radiative recombination
–
Charge exchange
–
(Photon excitation → Experiments at ultra brillant light sources)
–
Resonant recombination processes
(e.g. dielectronic recombination)
Dielectronic recombination (DR)
●
Example for KLL-DR: He-like system in initial state
Electron beam
Continuum
Diagnostics of trap content
http://www.ketek.net/produc
ts/axas/
Summary and Outlook
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Summary:
–
Simulation of electrostatic and magnetic field
–
Electron beam trajectory
–
Injection of ions
A tool for diagnostics in the near future:
–
Full Injection, charge breeding in the trap
–
Extraction of ions
–
Explore use of transition region and optimization
–
Assembly of the EBIS and commissioning in Heidelberg
–
Comparison of simulation results with real measurements
Thank you!
●
Special thanks to:
–
José R. Crespo López-Urrutia
–
Jens Dilling
–
Renate Hubele
–
Thomas M. Baumann
–
Michael A. Blessenohl
–
Zachary Hockenbery
Evolution of Charge State Distribution