KoBRA Wien Filter Project
1. Wien filter (Velocity filter)
- Ion optical element that can select the ions having the target velocity
- Perpendicular electric and magnetic fields
► Net force normal to the beam direction
-
![](/img/cens_en/contents/wien_filter_fig12.jpg)
- Mass Spectrometer, Monochromator, etc.
![In center of mass frame](/img/cens_en/contents/wien_filter_fig01.jpg)
Principal of the Wien filter
2. Purpose of the project
- Introducing a Wien Filter to the KoBRA beamline, the low-energy beamline at RAON
- Determining the specification of a Wien Filter considering the cost and ion optical performance
- Managing the purchase procedure and installation
3. Design
![Top and side view of the Wien filter](/img/cens_en/contents/wien_filter_fig02.jpg)
Top and side view of the Wien filter
![Good-Field Region (GFR) of the Wien filterr](/img/cens_en/contents/wien_filter_fig03.jpg)
Good-Field Region (GFR) of the Wien filter
![Schematic view of the Wien filter](/img/cens_en/contents/wien_filter_fig04.jpg)
Schematic view of the Wien filter
4. KoBRA Beam line
- Ion optical element that can select the ions having the target velocity
- Perpendicular electric and magnetic fields
► Net force normal to the beam direction
-
![](/img/cens_en/contents/wien_filter_fig12.jpg)
- Mass Spectrometer, Monochromator, etc.
![Install location of the Wien filter at KoBRA](/img/cens_en/contents/wien_filter_fig05.jpg)
Install location of the Wien filter at KoBRA
5. Specifications
- Dipole magnet
- Vacuum chamber including electrodes
- Magnet power supply, HV power supply x 2
![Field specifications](/img/cens_en/contents/wien_filter_fig06.jpg)
Field specifications
6. Performance Estimation
- Primary beam: 20Ne6+ (33 A∙MeV)
- Secondary beam: 18Ne (6 A∙MeV)
- Check the horizontal separation at the final focal plane (F3).
- Wien Filter can improve the beam purity with clear separation and better focusing.
![Performance estimation results using LISE++](/img/cens_en/contents/wien_filter_fig07.jpg)
Performance estimation results using LISE++
Optimal ion optics of KoBRA with Wien filter
![Performance estimation results using LISE++](/img/cens_en/contents/wien_filter_fig08.jpg)
KOSYG: KoBRA optics code for cOSY with Gui
![Performance estimation results using LISE++](/img/cens_en/contents/wien_filter_fig09.jpg)
Ion optics results with 14O8+ at 2.5 A∙MeV beam which is a typical beam produced by CRIB , RIKEN-CNS
![Performance estimation results using LISE++](/img/cens_en/contents/wien_filter_fig10.jpg)
Ion optics resu